Dental Development

Initial calcification of the primary tooth buds may be seen in the fourth month of prenatal life. In general, by the end of the sixth prenatal month, all of the primary teeth have begun to develop. The newborn infant is edentulous, with the rare exception of a mandibular central incisor. This natal or neonatal tooth tends to be quite mobile, and in the past it was thought to require immediate extraction. Recent data suggest that by the end of the neonatal period, this mobile tooth becomes quite stable and capable of normal masticatory function. This is indeed fortunate for the infant, because these neonatal teeth are frequently the only primary teeth that develop in that position (King and Lee, 1989; Cunha et al., 2001).

The sequence of eruption of human teeth may critically affect infant feeding, behavioral, and masticatory skills. Major changes in the appearance of the dentition in the oral cavity probably alter important aspects of neurobehavioral development (Wright, 2000). As an example of eruption sequence alterations, premature infants and neonates requiring prolonged orotracheal intubation have significant defects in both oral and dental structures that may persist past age 5 years, even after removal of the orotracheal tube (Fadavi et al., 1992).

The order of appearance of the teeth in the oral cavity tends to follow generalized patterns (Table 32-2). Usually the teeth erupt in pairs. A mandibular right central incisor erupts at approximately the same time as the mandibular left central incisor, at approximately 6 to 7 months of age. The mandibular teeth usually precede their maxillary counterparts; the maxillary incisors erupt approximately 1 month later than the mandibular incisors. The eruption sequence continues and is usually complete by age 2 to 2½ years. The last tooth to erupt is the deciduous second molar, called the 2-year molar because of its appearance at age 2 years.

TABLE 32–2 Eruption Sequence of the Human Dentition

From Schour I, Massler M: The development of the human dentition, JADA 28:1153, 1941. Reprinted by permission of ADA Publishing.

When completed, the primary dentition totals 20 teeth (Wright, 2000). As the toddler’s growth continues, the mandible and maxilla enlarge, causing separations, also known as diastemata, between the primary teeth (Zwemer, 1993). The diastemata increase as the primary teeth are beginning to exfoliate and the permanent or succedaneous teeth begin to erupt. The separations also permit sufficient room for the proper alignment of the permanent dentition.

The maintenance of the health and hygiene of the primary teeth is essential to avoid premature tooth loss. When primary teeth are prematurely lost as a result of decay or trauma, the space needed for the permanent tooth eruption is also lost because the natural tendency of the tooth is to tip mesially (toward the midline) in the oral cavity. Subsequently, dental malocclusions tend to occur. Finally, the primary teeth may also function as the permanent teeth if the permanent analogous tooth fails to develop (Wright, 2000).

The transition period between exfoliation of the primary teeth and eruption of the permanent teeth is called the mixed-dentition phase. This phase continues until the last primary tooth is normally exfoliated or extracted. Unlike the primary teeth, the permanent teeth normally erupt so that there is tooth-to-tooth contact.

Development of the secondary, or permanent, dentition begins at birth with calcification of the buds of the permanent first molars. The permanent dentition begins its eruption pattern with the permanent first molar, usually at approximately 6 years of age. Like their primary counterparts, the mandibular teeth usually precede the maxillary teeth, with the permanent mandibular incisors beginning to appear at approximately age 6 to 7 years. Unlike the primary dentition, where there is usually a variability of several months in the timing of eruption, the permanent teeth may vary as much as 1 to 2 years in eruption sequence. After eruption of the permanent first molars, eruption of the remaining permanent teeth then occurs in this sequence: mandibular central incisors, maxillary central incisors, mandibular lateral incisors, maxillary lateral incisors, mandibular cuspids, maxillary and mandibular first premolars, maxillary and mandibular second premolars, maxillary cuspids, and mandibular and maxillary second molars (see Table 32-2). At the completion of the eruption sequence, the permanent dentition consists of 32 teeth (Wright, 2000).

The third molars, commonly known as wisdom teeth, have the least predictable eruption sequence of any of the human dentition. They may erupt as early as age 15 to 16 years, as late as age 25 years, or not at all. Quite commonly, the third molars fail to erupt because of dental germinal pattern alterations or impactions in the soft or hard tissues. Impactions usually occur because of insufficient bony growth of the maxilla or mandible in proportion to the individual’s full dental complement.

In addition to the frequently absent third molars, two other permanent tooth forms are sometimes congenitally absent. The mandibular premolars and the maxillary lateral incisors may be congenitally absent, either singly or in symmetric pairs (Neville et al., 2002). Occasionally, a tooth that is thought to be congenitally absent is actually impacted in the soft tissues or alveolar bone.

Just as there are congenitally absent teeth, there are supernumerary or accessory teeth. The most common supernumerary tooth is the mesiodens, a conically shaped tooth consistently located in the midline between the maxillary central incisors. Other supernumerary teeth are the third premolars and fourth maxillary molars (Neville et al., 2002).

Identification of mobile primary versus transitional, or mixed, dentition can be of importance to anesthesia personnel. It is often recommended that mobile primary teeth be removed prior to airway instrumentation, as they may be at risk for dislodgment and airway obstruction. Likewise, it is important to note that newly erupted permanent teeth are often slightly mobile, with incomplete root formation. For this reason, extra care should be taken during laryngoscopy, oral airway placement, or other jaw manipulation, as immature permanent teeth may be predisposed to luxation or avulsion trauma if too great a force is placed on them.

Dental Identification

There are two principal universal dental identification systems. In both systems, the primary teeth are designated by letters, and the permanent teeth are designated by numbers. These systems differ in the way that the dental arches (mandible and maxilla) are divided. The first system uses a sequential means for identification, with the primary maxillary right second molar designated as tooth A and followed sequentially around the contralateral side of the maxilla to the left second molar, which is tooth J. The primary mandibular left second molar is tooth K, and the sequence is completed on reaching the mandibular right second molar, tooth T. Similarly, the numbering system for the permanent dentition starts with the maxillary right third molar as tooth 1 and continues to the maxillary left third molar, tooth 16. The sequence continues with the mandibular left third molar, tooth 17, and is completed with the mandibular right third molar, tooth 32 (Herlich, 1990). Both pediatric and general dentists commonly use this system of tooth identification.

The second designation system divides the dental arch into quadrants. All primary central incisors are tooth A and follow distally or posteriorly, so that all primary second molars are tooth E. To make the designation more specific, the quadrant is also named. For example, the primary maxillary right lateral incisor is designated maxillary right B. Similarly, the permanent dentition is divided into quadrants. All central incisors are tooth 1 and continue posteriorly, so that all third molars are tooth 8. This system is most commonly used by orthodontists (Fig. 32-1).

FIGURE 32-1 A, Tooth identification and sequence. B, Cast models of the primary dentition (upper) and permanent dentition (lower).

(A, From Herlich A: Dental complications of anesthesia, Prog Anesthesiol 11:250, 1990. B, From Ash MM Jr, editor: Wheeler’s dental anatomy, physiology, and occlusion, ed 7, Philadelphia, 1993, Saunders, p 2.)

Dental Anatomy and Physiology

The tooth is composed of a crown, which is usually visible for clinical examination, and a root, which is not seen during routine clinical examination. They are separated by the cementoenamel junction or cervical region of the tooth (Fig. 32-2). The cementoenamel junctions are seen more commonly in adult dentition if gingival (“gum”) recession occurs. The crown is responsible for the slicing, ripping, and grinding of foodstuffs (incisors, canines, and molars, respectively). The root structure imparts stability to the tooth in its surrounding tissues. The anterior teeth, the incisors and the canines, are single rooted with a conical shape. The posterior teeth, the premolars and molars, are multirooted and impart most of their stability by both the number of roots and the subtly divergent directions in which the roots may grow.

FIGURE 32-2 Schematic (left) and radiographic (right) views of a right maxillary molar.

(Modified with permission from Ash MM Jr, editor: Wheeler’s dental anatomy, physiology, and occlusion, ed 7, Philadelphia, 1993, Saunders, p 6.)

Surrounding the root structure of the tooth is the periodontium, which is composed of three structures as follows:

The individual teeth are composed of enamel, dentin, dental pulp, and cementum (Wright, 2000) (see Fig. 32-2). The enamel covers the external surface of the dental crown. It is the hardest substance in the human body and, unlike bone, has no living cells. When intact, enamel functions as a thermal insulator and an impervious barrier to chemicals and microorganisms.

On the internal surface of the enamel lies the dentin. It is composed of microtubules and has living cells in the dentinal structure. When tooth decay is advanced, noxious stimuli are readily transmitted via the dentinal tubules to the underlying dental pulp. The neurovascular supply of the individual teeth is contained in the dental pulp. Pain is easily elicited by many different stimuli—thermal, tactile, or liquid. The pain is transmitted from the dental pulp through the root apices to the alveolar bone and subsequently to the body’s pain receptors.

The final portion of the tooth structure is the dental cementum, which covers the external surface of the roots. Because it is not nearly as hard and impervious to the surroundings as is enamel, noxious stimuli are perceived when the cementum is exposed. The cementum is similar to the dentin of the tooth. Patients who enjoy good dental health usually do not have exposed cementum. However, with gingival and alveolar recession, root structure and its investing cementum may be exposed to the external environment.

Some morphologic differences exist between deciduous and succedaneous teeth. The most obvious difference exists in the size of the teeth in general. The deciduous teeth are significantly smaller than their permanent counterparts. With respect to the molars, the buccal-lingual dimensions are proportionately narrower. In contrast, the mesial-distal dimensions are proportionately larger.

Another difference between the sets of dentition rests in the color of the enamel. The primary teeth are milky white, or opalescent; hence, the name milk teeth. The permanent teeth, on the other hand, are significantly less “milky” because pigment absorption has occurred during their development or has been acquired during the intraoral lifetime of the tooth (Wright, 2000). Two examples are tetracycline staining (developmental) and caffeine staining (acquired).

The pulp chambers of the primary teeth are larger than the permanent teeth because of the relative thinness of the deciduous enamel and dentin (Wright, 2000). Less than meticulous dental restorations or large carious lesions may predispose the primary teeth to pulpal or endodontic therapy earlier than their permanent counterparts.

The root structures of the primary molars are more saber shaped and extend laterally beyond the crown width. This unique root structure allows adequate room for the permanent tooth bud to develop and mature until the exfoliative process is completed for the primary tooth (Wright, 2000).

Orthodontic Pathology

Teeth erupt into the alveolar processes of the maxilla and mandible and are held into bone by the periodontal membrane and gingival fibers. Together, the teeth and the jaws provide structure to the lower third of the face. In a normal bite, the maxilla and maxillary teeth are larger, which allows the maxillary arch to overlap the mandibular arch. Occlusion describes how maxillary and mandibular teeth fit together during chewing or at rest.

Malocclusion is the improper alignment of the teeth and jaws or bad bite. A skeletal malocclusion describes a malalignment between the jaws. A dental malocclusion describes the interarch relationship between the upper and lower teeth. A malocclusion may be caused by both hereditary and environmental factors. Crowding, spacing, supernumerary teeth, hypodontia, and asymmetric jaw growth are determined mostly by inheritance. Environmental factors such as thumb sucking, dental caries, premature loss of primary teeth, and trauma also can contribute to malocclusion (Mossey, 1999). An untreated malocclusion can lead to tooth decay, periodontal disease, abnormal wear of teeth, difficulty in chewing and speaking, and poor self-image.

Edward H. Angle, who is regarded as the father of orthodontics, developed a classification system for malocclusion based on the sagittal (anteroposterior) relationship of the teeth and jaws (Angle, 1899). Angle believed the upper first molars were critical to occlusion, and that the upper and lower molars should meet so that the mesiobuccal cusp of the upper molar contacts in the buccal groove of the lower molar. If this molar relationship existed and the teeth were arranged on a smoothly curving line of occlusion, then normal occlusion would result (Fig. 32-3). Angle’s classification system is as follows:

FIGURE 32-3 Angle classification system for malocclusion.

Discrepancies in the vertical or transverse dimension can also contribute to a malocclusion. An openbite or deepbite describe how teeth fit together in the vertical dimension.

Whether orthodontic treatment should occur in one or two phases of treatment is a source of controversy. Phase I, or early orthodontic treatment, may correct a problem when the patient still has primary teeth or has a combination of primary and permanent teeth. Some practitioners believe it may keep more serious problems from developing, and it may make treatment at a later age shorter or less complicated. Typically, early treatment involves the use of materials and techniques to guide or modify growth as adult teeth are erupting (Kluemper et al., 2000)

Appliances used in early treatment may be removable or fixed (cemented). They may be made of metal, ceramic, or acrylic. Examples of appliances used to address transverse discrepancies include palatal expanders, quad helixes, and transpalatal arches (Fig. 32-4). Headgear therapy may be used to treat anteroposterior discrepancies (class II or class III malocclusions) and are composed of a removable and fixed component. A lower lingual holding arch is a banded appliance used to maintain space for the eruption of permanent teeth in the mandibular arch (Fig. 32-5). Functional appliances change the position of the lower jaw to produce movement of teeth and modification of growth. Examples of functional appliances include the Twin block, Herbst appliance (Fig. 32-6), and Bionator.

FIGURE 32-4 Appliances used to address transverse discrepancies include bonded palatal expander (A), banded palatal expander (B), quad helix (C), and transpalatal arch (D).

FIGURE 32-5 A lower lingual holding arch.

FIGURE 32-6 Herbst appliance, used to change the position of the lower jaw.

Phase II or active treatment involves placement of fixed appliances (braces) or Invisalign in the permanent dentition (Boyd, 2008). Treatment times vary with several factors, including the severity of the problem being corrected, patient response to treatment, and patient compliance. Temporary anchorage devices (Fig. 32-7) are implants used to provide absolute anchorage and help move teeth (Cope, 2005). Patients use retainers to keep teeth in their new positions after treatment.

FIGURE 32-7 Temporary orthodontic anchorage devices.

Combined surgical orthodontic treatment is used to treat patients with severe malocclusions or craniofacial anomalies. Presurgical orthodontic treatment is used to prepare patients for surgery by removing dental compensations and upright teeth over basal bone (Proffit and Miguel, 1995). In a traditional orthognathic procedure, a surgical splint may be fabricated and wired to the patient’s teeth. This splint may help the surgeon determine the final position of the jaws.

Nasoalveolar molding (NAM) is a presurgical orthopedic technique used to reduce the severity of the cleft deformity in infant patients with complete unilateral or bilateral cleft lip and palate (Grayson et al., 1999). The appliance is composed of a removable acrylic plate fabricated from an intraoral impression, and a nasal stent (Fig. 32-8). The amount of acrylic is sequentially reduced to decrease the separation between the greater and lesser alveolar segments. Once the gap between the alveolar segments is 5 mm or less, the nasal stent is added to mold the nasal cartilage. Lip or nasal repair occurs at 4 to 6 months of age. Patients with NAM can present for cleft lip surgery or ear, nose, and throat procedures such as myringotomy and tubes. The NAM appliance can be left in place during inhalation induction and mask ventilation, or it can be removed before the beginning of induction. The device should be removed before airway instrumentation for a laryngeal mask airway (LMA) or endotracheal tube.

FIGURE 32-8 Nasoalveolar molding.

Facial Cellulitis

Bacterial abscess can spread from the apex of the root of the primary or permanent tooth into the surrounding alveolar bone and periosteum into deep tissue planes of the face or neck, resulting in an odontogenic facial cellulitis. Fever, dysphagia, leukocytosis, trismus, and dehydration are common physical findings. The lateral pharyngeal, retropharyngeal, masticator, buccal, submandibular, and submental spaces may be involved. Appropriate antibiotic therapy and prompt surgical drainage and extraction of the infected tooth are critical components of care.

Careful preoperative airway evaluation is critical in patients with facial cellulitis. Involvement of the masticator space or other anatomic spaces of the neck may threaten the airway. Ludwig’s angina, with bilateral involvement of the submandibular space and with associated superior displacement of the tongue base can cause airway compromise.

Clinical Settings for Pediatric Dentists

Most pediatric dental treatment occurs in the dental office without the need for psychological or pharmacologic intervention to address the child’s fear and anxiety. The hallmark of dental pain management is a kind practitioner and staff and the responsible use of adequate local or topical anesthesia, or both. For some patients, simple behavior modification techniques improve the level of cooperation in the dental chair. These techniques include the tell-show-do method and voice control for the fearful, hostile, or disruptive child. The tell-show-do technique involves explaining before the procedure, demonstrating the procedure outside of the child’s mouth, and then actually performing the procedure on the patient. This technique removes the fear of the unknown from the procedure (Lenchner and Wright, 1975). Voice control involves modulation of both the volume and tone of the dentist’s voice to achieve positive behavioral results (Wilson, 1994; American Academy of Pediatric Dentistry, 2008). When behavior modification is deemed necessary for a preschool child, it should be scheduled during the morning, because the child’s longest attention span and optimal level of cooperation are early in the day. Additional techniques include positive reinforcement, distraction, and parental presence (American Academy of Pediatric Dentistry, 2008). Additional behavior modification techniques have been used by the dentist to physically restrain frightened children. This protective stabilization is the restriction of the patients’ freedom of movement, with or without their permission, to decrease the risk of injury and to allow the safe completion of the treatment. Included in these techniques are passive physical restraint with a rigid board (papoose board), and active physical restraint by dental personnel. These techniques are controversial because of their potential psychological trauma and legal implications (Nathan, 1989; Wilson, 1994; Wright, 1994). Continuous monitoring of the patient is essential during protective stabilization.

Most analgesia for pediatric dental procedures is achieved by local anesthetic block. Most blocks are local infiltration in the maxillary region, or mandibular nerve blocks in the mandible. Adverse reactions to local anesthetics seldom occur when they are administered alone. Most commonly, they are related to a relative overdose or lapse in technique. However, even a low dosage, inappropriately injected, can cause palpitations, diaphoresis, or even dizziness (Kaufman et al., 2000). Rarely does vasomotor collapse occur. True allergic reactions, including allergy to metabisulfite or other preservatives of local anesthetics (e.g., paraaminobenzoic acid), are probably the smallest proportion of untoward reactions (Campbell et al., 2001).

Behavior modification may include such novel approaches as hypnosis or music therapy. Highly motivated, intelligent, attentive, or anxious children may have a good emotional and analgesic response to hypnosis when other forms of behavior modification, including pharmacologic forms, are precluded (Kleinhauz and Eli, 1993). Children as young as 3 to 4 years may be successfully hypnotized in the dental office (Lampshire, 1975). Music did not diminish pain, anxiety, or disruptive behavior in a recent study (Aitken et al., 2002), despite anecdotal beliefs of pediatric dentists and parents. Nevertheless, in this study, the patients enjoyed listening to the music and chose to listen to music in subsequent visits.

Electroanesthesia (transcutaneous electronic nerve stimulation [TENS]) has been used successfully for children in the dental office setting. TENS is reported to be effective based on several interrelated theories. These pain control theories include gate control, endorphin release, and serotonin release. For dental procedures, disposable electrode pads are placed bilaterally in the treated dental arch after drying the buccal mucosa. Using a dentally specific TENS device, a pulse rate of 110 Hz, and a pulse width of 225 microseconds in the normal mode, amplitude is slowly increased until the desired response is obtained. Twitching of the lower lip is the amplitude end point in the mandibular arch, and twitching of the orbicularis oculi is the amplitude end point in the maxillary arch. Children are instructed to raise a hand if the amplitude is too uncomfortable, and it is then diminished (te Duits et al., 1993). This technique works best in the area of restorative dentistry in the teeth that have relatively shallow lesions with respect to the dentoenamel junction (Quarnstrom, 1992; te Duits et al., 1993).

The spectrum of use of sedation is illustrated by the fact that medication, including nitrous oxide, is being used less than in previous years and studies. A study by Houpt (2002) suggests that, although more sedation is being used, it is being used by fewer practitioners on more patients in the United States.

A retrospective review of pediatric sedation management suggests that at one U.S. dental school pediatric dental clinic, nonpharmacologic behavioral management is favored more frequently because of its greater success (Eid, 2002). One British study estimated that more than 300,000 general anesthesias are still being administered for dentistry each year in Great Britain, mostly for children. The authors suggest that fewer general anesthetics are available for dentistry now than in the 1970s (Blayney et al., 1999). It is implied that most general anesthesias in Great Britain, however, as opposed to in the United States, are provided in a hospital setting.

Most pediatric dentists and those treating handicapped patients are experienced in the use of nitrous oxide and oral premedication when necessary in the dental office. The reported advantages of nitrous oxide delivered via a Goldman nasal mask include analgesia and sedation (Nathan et al., 1988). The incidence of diffusion hypoxia is minimal after the use of nitrous oxide and oxygen alone, as opposed to nitrous oxide supplementation to parenteral or oral sedatives (Quarnstrom et al., 1991; Dunn-Russell et al., 1993). Hypoxemia may occur when 30% to 50% nitrous oxide is added to chloral hydrate sedation (Litman et al., 1998b). In a recent study, nasal midazolam and nitrous oxide resulted in satisfactory sedation in 96% of the pediatric patients without any clinically relevant oxygen desaturation (Wood, 2010). However, in children with enlarged tonsils, oral midazolam (0.5 mg/kg) and 50% nitrous oxide resulted in significant upper airway obstruction and implied hypoxia (Litman et al., 1998a).

Patients classified by the American Society of Anesthesiologists (ASA) as having physical status I or II are appropriate candidates for treatment with pharmacologic adjuncts in the dental office setting. If a child’s physical status is III or beyond, the hospital setting is probably a wiser choice. It must be emphasized that the pediatric dentist should use local anesthesia to optimize analgesia and anesthesia for the patient. Local anesthesia may add to the potential complications of polypharmacy if attention is not paid to dosages that are age and weight appropriate. This is especially true in the pediatric age group. The pediatric dentist rarely uses intramuscular or intravenous sedation while serving as both the operator and the practitioner administering the sedation.

The reports of severe adverse outcomes include hypoxic brain damage and occasional deaths, with the use of nitrous oxide, local anesthesia, and other premedicants. Anesthesiologists should have an active role in the training of pediatric dentists in techniques of anxiolysis and moderate sedation. Adverse outcomes will likely be diminished under these circumstances (Herlich, 2010; Costa et al, 2010). Invariably, these adverse outcomes result from relative or absolute overdosage of one or a combination of nitrous oxide, local anesthetic, and parenteral medication (Goodson and Moore, 1983; Doyle and Goepferd, 1989; Coté et al., 2000a). Because of the widely publicized adverse outcomes of dental office sedation and general anesthesia, the trend in this type of care has been to move away from the dental office unless guidelines for deep sedation and anesthesia by the American Academy of Pediatric Dentistry are followed. These guidelines were promulgated in 1985 and restated in 2006 to promote and ensure that the public is aware and the pediatric patient is protected. The guidelines describe that the anesthesia care provider must be a separate individual with appropriate licensing, credentialing, and training to perform deep sedation and general anesthesia.

In the United Kingdom, a group of investigators performed several retrospective analyses during the 1970s and 1980s. Retrospective data obtained from a national data bank indicated that dental office deaths were infrequent, and the number decreased substantially in the second survey. The decreases in deaths probably result from two factors. First, fewer general anesthesias were being administered in the dental office. Second, the practice of the single individual being both dental practitioner and anesthetist is becoming less frequent because of warnings and suggestions from the General Dental Council of Great Britain. The anesthetist and dental practitioner are more commonly two individuals, each of whose attention is directed toward a single task. Also, the British survey indicated that the person providing anesthesia is more commonly a physician (Coplans and Curson, 1982, 1993). In the United States, closed claims morbidity and mortality involving oral surgeons show that during the period of 1988 to 1999, there were 22 deaths in the office and 136 anesthesia-related claims in total. It was calculated that the death rate was 1 in every 747,732 (0.013 in 10,000) administrations of anesthesia in the dental office (Deegan, 2001). D’Eramo and colleagues (2008) in a survey of oral maxillofacial surgeons in Massachusetts found the adult death rate to be 1 in 1,733,055 from office-based anesthesia. Data from the Pediatric Sedation Research Consortium indicated no mortality in over 49,000 propofol sedations, of which 307 were for dental procedures (Cravero et al., 2009).

In the United States, opposing forces create difficulties for the pediatric dental patient. Economic issues tend to restrict hospital-based procedures, including payment for the dental service only, without payment for the anesthesia service; payment for the anesthesia service only, without payment for the dental service; and frequently no payment or only partial payment for the hospital service. Frequently, the patient’s family is faced with a significant out-of-pocket expense, which many cannot afford. On the other hand, the litigious nature of our society has prevented the rational expansion of anesthesia services in the office environment beyond sedation. Mandated equipment and monitors and the cost of liability insurance may be prohibitive for the office practitioner.

Another issue with significant economic ramifications is the cost of multiple treatments in the dental office with procedural sedation as opposed to a single session in the operating room of the hospital under general anesthesia. In studying healthy patients aged 24 to 60 months, Lee and colleagues (2001) found that a patient who required more than three treatment visits with procedural sedation had more cost-effective treatment when all of the treatments were provided in a single visit under general anesthesia.

A reasonable compromise may be a well-equipped hospital or surgicenter dental clinic with standard monitoring devices and resuscitation equipment. Pediatric patients with ASA status I or II may be suitable candidates. With the use of proper equipment and appropriately trained personnel, a large diversity of patients may be safely and satisfactorily treated on an outpatient basis. If the clinic is rationally designed, including recovery areas equipped with oxygen, suction apparatus, and essential monitoring devices, the anesthesiologist can safely administer the anesthetic outside of the traditional operating room setting. It allows more efficient use of time and space as well as reduced cost. From the perspective of the parent and child, outpatient treatment permits a more rapid return to familiar surroundings and activities of daily living (Zuckerberg, 1994). Only the patients with disease or physical conditions that preclude off-site clinical practice need to be treated in the operating room in today’s environment. Some examples of the patients who may need the traditional operating room setting include those with difficult airways, those with coagulopathies, and those with complex anomalies or cardiovascular disease for whom more than standard monitoring is necessary.

Procedural Sedation

In 1985, The American Academy of Pediatric Dentistry established goals for sedation of the pediatric dental patient. These goals were updated in 2006 and are as follows:

With these goals in mind, procedural sedation of the pediatric dental patient may be considered. The foundations of pharmacologic sedation for the pediatric dental patient are monitoring standards to which all practitioners should adhere (Wilson, 2000). Minimum or moderate procedural sedation intended in the sensitive patient may become deep sedation or general anesthesia if vigilance is not applied. These standards have been promulgated by several organizations, including the ASA (2002), The American Academy of Pediatric Dentistry and American Academy of Pediatrics (McGuire, 2007), and the American Academy of Pediatric Dentistry (2002d) (Consensus Conference, National Institutes of Health, 1985; Rosenberg and Campbell, 1991; Council on Scientific Affairs, AMA, 1993). The American Academy of Pediatric Dentistry guidelines suggest that children who are status ASA III or IV should have treatment that necessitates sedation performed in a hospital environment.

The use of precordial/pulse oximetry for nitrous patients is not supported for nitrous oxide alone in the 2009 American Academy of Pediatric Dentistry Guidelines (American Academy of Pediatrics and American Academy of Pediatric Dentistry, 2006). Additionally, a full E-cylinder of oxygen and a self-inflating bag and mask capable of delivering 15 L/min of oxygen must be available in the care facility. An important monitor is a trained individual whose sole duty is to pay attention to the electronic and mechanical monitors in place and who is prepared to act on untoward events. As mentioned, the treating dentist should not be the person administering the anesthetic.

Before any sedation is administered, including nitrous oxide with oxygen, appropriate fasting guidelines must be given to the parents or guardians of the patient. Data suggest that prolonged fasts meant to reduce the likelihood of vomiting and aspiration are somewhat deleterious to patient outcome. Guidelines for fasting from solid foods, milk, and milk products remain at a minimum of 8 hours. However, clear liquids, including pulpless juices, plain gelatin, and ice popsicles, are encouraged and acceptable until 2 hours before the anticipated arrival in the care facility. The pediatric patient is more cooperative and the parents are more satisfied as a result of these suggested guidelines (Schreiner, 1994). All of these guidelines are predicated on normal gastrointestinal function. If the patient has abnormal gastrointestinal function, more conservative fasting orders must be considered.

Oral, intranasal or transoral, parenteral, and rectal routes for administration of sedative medications are used during procedural sedation. Pediatric dentists have traditionally and preferentially used the oral route to administer premedication (Primosch and Bender, 2001). The old practice of having the parents administer a prescribed oral medication at home has been fraught with danger to the toddler and young child. Airway obstruction and emesis with aspiration were real complications of that practice. For reasons of safety, the practice has changed. Children are now brought to the treatment facility or dental office 1 hour ahead of the scheduled procedure time, and the oral premedication is administered under the guidance of the pediatric dentist. Two of the most popular agents have been hydroxyzine (1 to 2 mg/kg) and chloral hydrate (50 to 75 mg/kg; maximal dosage, 2 g). These agents have had a good success rate and a reasonable margin of safety. In addition, nitrous oxide may be given in conjunction with the usual administration of local anesthetic blocks (Moore et al., 1984; Shapira et al., 1992). More potent oral agents, such as ketamine, diazepam, and midazolam, are also given in the treatment facility or dental office. The practitioner must allow a reasonable time for onset of action before dental treatment (Sullivan et al., 2001). Oral midazolam has gained widespread popularity because of its reasonable margin of safety in addition to its rapid onset for either premedication before general anesthesia or as the main agent for procedural sedation (Kupietzky and Houpt, 1993; Levine et al., 1993). These agents may be given alone or with another agent (Dallman et al., 2001; Bui et al., 2002; Nathan and Vargas, 2002).

Mild oxygen desaturation has been noted and is easily treated with supplemental oxygen and repositioning of the patient’s airway. In some cases, when nitrous oxide was added to the oral premedication, the degree of hypoxemia increased (Litman et al., 1998a). The use of traditional monitors such as clinical observation, blood pressure, and pulse was clearly insufficient to assess the degree of hypoxemia. Pulse oximetry, capnography, and precordial stethoscopes have become necessary to adequately assess and prevent poor outcomes despite limitations in the pediatric dental environment (Anderson and Vann, 1988; Poiset et al., 1990; Wilson, 1990; Dunn-Russell et al., 1993). The use of supplemental oxygen also helps to reduce hypoxemia. Novel means of improving oxygenation include the delivery of supplemental oxygen via the saliva injector and the use of external nasal dilators (Milnes, 2002; Moses and Lieberman, 2003).

Intranasal or transoral administration of water-soluble agents such as ketamine, midazolam, or sufentanil produces effective sedation and premedication for procedural sedation. However, sufentanil produces a significantly high incidence of respiratory depression, even in relatively small dosages (1.0 mcg/kg) and is not recommended (Abrams et al., 1993). Midazolam (0.5 mg/kg orally, or 0.2 to 0.3 mg/kg intranasally) is ideal for creating a milieu in which the child is easily separated from the parent. It also transforms a disruptive child into a quiescent child in the dental chair with minimal desaturation (Abrams et al., 1993; Levine et al., 1993). However, once the handpiece (dental drill) was activated, the noise distracted the child sufficiently that the pediatric dentist could not efficiently treat the child (Theroux et al., 1994). Despite the popularity of oral sedation, one group of investigators found that there was no relationship between oral sedation and behavior of the children in the dental office on subsequent visits (McComb et al., 2002).

The rectal route of administration for procedural sedation and premedication has enjoyed popularity with only a small number of practitioners. Midazolam (1.0 mg/kg or even higher dosages) has been used for procedural sedation and for premedication. Onset of action usually occurs within 15 to 30 minutes (Roelofse and Van der Bijl, 1991). The main drawback to rectal administration of these agents is the risk of expulsion of the sedative and the unreliable uptake from the distal colonic mucosa.

Many drugs have been used as parenteral agents for procedural sedation in pediatric dentistry. Opioids, benzodiazepines, antihistamines, ultra-short-acting barbiturates, and dissociatives have been used successfully. All have had some negative features as well. Short-acting agents with acceptable margins of safety in dental sedation include methohexital, meperidine, ketamine, diazepam, and midazolam. Respiratory depression and concomitant hypoxia have been the recurrent theme in parenteral sedation by pediatric dentists (Allen, 1992; Coté et al., 2000a, 2000b). As previously mentioned, clinical observation was insufficient and the airway was subsequently lost. Because of the fine line between moderate procedural sedation, deep sedation, and general anesthesia, the dentist and assistant who administer procedural sedation must be experienced in recognizing and handling cardiorespiratory depression. Electrocardiography, pulse oximetry, blood pressure, capnography, and precordial stethoscope are essential monitors (American Academy of Pediatrics and American Academy of Pediatric Dentistry, 2006).

Other drawbacks to intravenous sedation in pediatric dentistry have been the potential for inflicted pain to achieve intravenous access and the lack of familiarity with drug combinations on the part of the practitioner. The child’s fear of pain from a needle puncture has been successfully addressed by inhalation of nitrous oxide in oxygen or the transmucosal administration of midazolam. Use of EMLA (eutectic mixture of local anesthetics, 2.5% lidocaine, and 2.5% prilocaine) cream or topical (ELA-Max) lidocaine cream before venipuncture has been successful in reducing or eliminating needle puncture pain (Nilsson et al., 1994; Koh et al., 2004). Also, EMLA- and lidocaine-impregnated patches have been used intraorally with varying success before local anesthetic blocks and local procedures before the insertion of rubber dam clamps (Stecker et al., 2002). The main disadvantage of the use of the transdermal local anesthetics in EMLA cream is that it requires application at least 45 minutes to 1 hour before a painful procedure. ELA-Max is faster and requires approximately 30 minutes to take effect (Koh et al., 2004).

General Anesthesia

The American Academy of Pediatric Dentistry (2002d) has issued guidelines for the indications for general anesthesia for children having dental procedures (Box 32-1). Nunn et al. (1995) also described the indications for general anesthesia in 265 pediatric patients. These indications include extensive treatment needs, behavior management issues, medically compromised children, extreme anxiety, and physical disabilities. The most common indication, accounting for 30.6% of the anesthesias, was intellectual impairment and autism. Dental phobia accounted for 21.4% of the patients.

Behavioral issues are a very common indication for sedation or general anesthesia in children. The behavioral issues may stem from fear and anxiety or an abnormality in development such as autism, autism spectrum disorders, cerebral palsy with mental retardation, and Down syndrome.

Fear of dental procedures affects all ages. For some it may be so strong that dental visits are avoided altogether. In children, anxiety prior to a surgical or dental procedure centers on the fear of pain, loss of control, and separation from the parent or guardian. Preoperative anxiety and its risk factors are discussed in Chapter 8, Psychological Aspects of Pediatric Anesthesia, and Chapter 9, Preoperative Preparation. Children most at risk for heightened anxiety are between 1 and 5 years old and have divorced parents, previous negative medical experiences, and heightened emotionality (Kain et al, 2007).

Autism is an abnormality in neurodevelopment that results in abnormal social interactions and recurrent repetitive behavior. The diagnostic criteria include age of onset of less than 3 years old, severe abnormality of social reciprocity, severe abnormality of communication development, and restrictive, repetitive patterns of behavior and imagination (Klein and Nowak, 1998). The incidence of autism is increasing and is now estimated to be 1 to 2 per 1000 (Newschaffer et al., 2007). Autism spectrum disorders are a heterogeneous group of disorders that include autism, Asperger’s syndrome, Rett syndrome, and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS). Children with autism and autism spectrum disorders can be uncooperative and often require behavioral interventions, sedation, or general anesthesia to complete a dental examination or procedure.

The child with significant medical disorders may require the assistance of an anesthesiologist during dental care. Some of these medical disorders may include the child with a known difficult airway, congenital cardiac disease, or multiple coexisting disorders. Children with cyanotic congenital heart disease may require SBE prophylaxis (Box 32-2). The appropriate antibiotic selection is summarized in Table 32-3. Patients with one of the cardiac conditions in Box 32-2 having dental procedures that manipulate the gingival tissue or periapical region of the teeth or perforate the oral mucosa require SBE prophylaxis. Procedures that do not require prophylaxis include routine anesthetic injections through noninfected tissue, taking dental radiographs, placement of removable prosthodontic or orthodontic appliances, adjustment of orthodontic appliances, placement of orthodontic brackets, shedding of deciduous teeth, and bleeding from trauma to the lips (Wilson et al., 2007).

Airway Management

Management of the airway during general anesthesia for dentistry begins with mask ventilation. If the patient has a NAM device in place, it can be removed before initiating mask ventilation. If the device does not interfere with mask ventilation, it can be left in place until the airway is instrumented. Intubation for dental procedures is typically performed nasally to keep the mouth clear for the dentist or oral surgeon. During the preoperative examination, a history of epistaxis should be elicited, and the nares should be inspected for evidence or recent nosebleeds. A child who is old enough may be able to breath through the nares individually to determine which one is more patent. Despite these preoperative tests, epistaxis may still be a significant issue.

Preparation of the nasal cavity is essential to minimize the risk of bleeding and to optimize the laryngoscopic or fiberoptic view. Once the child has been anesthetized, a mucosal vasoconstrictor such as oxymetazoline (Afrin) is applied to the nasal mucosa in both nares. The dosage for the child between 2 to 5 years of age is 2 to 3 drops of a 0.025% solution in each nostril (Mcgee et al., 2009). Oxymetazoline can be administered as drops or it can be applied via nasal cottonoids. There is controversy regarding the use of topical vasoconstrictors. Some pediatric anesthesiologists choose not to use topical vasoconstrictors (phenylephrine or oxymetazoline) because of concern about cardiac complications (e.g., pulmonary edema and cardiac arrest) (Thrush, 1995; Groudine et al., 2000). Systemic absorption of the vasoconstrictor can result in profound systemic vasoconstriction and hypertension. Pulmonary edema occurs secondary to β-blockade treatment of the hypertension.

Before introduction of the nasal endotracheal tube, each naris should be assessed to determine which is the most patent. A lubricated nasal pharyngeal airway can be passed into each naris to accomplish this. The most effective way to determine the best anatomic route for nasal intubation is to fiberoptically inspect each nares. Previously unidentified anatomic abnormalities are most likely to be found with this technique (Smith and Reid, 1999).

Other techniques to minimize bleeding during nasotracheal intubation in children include reducing the size of the endotracheal tube (ETT) by a half to a full size, warming it in warmed saline, and telescoping its end into a rubber catheter (Elwood et al., 2002; Watt et al., 2007). The incidence of bleeding appears to be reduced when the ETT is warmed in saline. The reduction in bleeding is even more pronounced when its tip is covered with a rubber catheter prior to introduction into the naris. In Watt’s study, 56% of children who had a room temperature ETT placed had clinically significant bleeding. This was reduced to 39% if the ETT was exposed to warm saline, and it was reduced even further (to 5%) when the tube was telescoped with a rubber catheter. A final technique is to use an obturator, which can be an esophageal stethoscope (Seo et al., 2007), a suction catheter (Herlich et al., 1996), or a fiberoptic scope. Beside bleeding, complications of nasotracheal intubation include bacteremia, dislodgment of adenoidal tissue, and laceration of aerodigestive mucosa with subsequent false passage. Turbinate ulceration may also occur. Fiberoptic guidance of nasotracheal intubation may reduce some of the attendant comorbidities that the anesthesiologist may face (Herlich, 1991). Once the tip of the ETT is positioned in the posterior pharynx, it can be guided into the larynx with direct laryngoscopy or with a flexible fiberoptic scope.

Nasotracheal tubes need to be secured in a way that avoids alar pressure (Fig. 32-9). Prolonged alar pressure can result in tissue ischemia and loss. In addition, the eyes must be protected and the forehead padded.

FIGURE 32-9 One method of taping a nasotracheal tube. Note there is no alar pressure.

Fiberoptic intubation may become the rule rather than the exception in patients with facial trauma (Kaban, 1993), mandibulofacial dysostosis (Treacher Collins syndrome), and other congenital craniofacial anomalies (Pierre Robin sequence, Goldenhar’s syndrome). These patients frequently have palatal clefts and severe dental problems that require dental therapy and possibly orthognathic surgery (Gendelman and Herlich, 1993).

Patients with a history of recurrent epistaxis, recent nasal trauma, or recent head trauma should potentially not have a nasal intubation performed. In these patients, a straight ETT or an oral RAE tube can be used. A preformed orotracheal tube, such as the oral RAE tube, may be disadvantageous because it is designed to be a midline tube. Moving the preformed tube to either side of the mouth may cause an eccentric positioning in the trachea. An endobronchial intubation may create difficulties in ventilation. If orotracheal intubation is needed, a conventional ETT easily moves to either side of the mouth and oropharynx with the compensatory eccentric tracheal position of the tube. Another concern with moving an oral ETT from side to side is the increased risk of unintentional extubation. An oral tube also decreases the ability of the dental operator to place a rubber dam and complete the dental treatment efficiently. Suboptimal position and placement of dental instruments may also occur when an orotracheal tube is in place. A pharyngeal pack reduces the likelihood that blood and debris are introduced into the aerodigestive tract. Noting the times of insertion and pack removal from the pharynx on the anesthesia record reduces the risk of airway embarrassment postoperatively.

The armored version of the LMA, or flexible LMA, may be indicated for some pediatric dental patients who need dental care under general anesthesia. The advantages of the LMA are its ease of placement and tolerance in the spontaneously ventilating patient. Like an orotracheal tube, it has disadvantages, including its presence in the oral cavity, the interference with rubber dam placement, and its larger size in comparison with a standard orotracheal tube. With a skilled pediatric dentist performing restorative dentistry or surgical procedures, minimal hemorrhage may be seen on the LMA at the end of the procedure (Alexander, 1990; Webster et al., 1993).

Despite meticulous technique on the part of the pediatric dentist who is placing a rubber dam, dental materials may lodge in the oropharynx and subsequently enter the laryngotracheobronchial tree. Hence, a gentle but thorough cleaning and suctioning of the oropharynx before extubation are mandatory.

Dental Complications of Anesthesia

The dental complications of anesthetic care are varied, usually minor, but a frequent source of malpractice claims. Most minor injuries are settled without going through malpractice litigation. The incidence of periperative dental injury is based on retrospective data and varies from 0.02% to 0.05% (Lockhart et al., 1986; Warner et al., 1999; Newland et al., 2007). In one study of a large tertiary medical center, the frequency of perianesthetic dental trauma requiring repair, stabilization, or removal of the tooth was approximately 1 in 4500 cases (Warner et al., 1999). Nevertheless, the anesthesiologist must be aware of the potential pitfalls and take appropriate safeguards. If a dental complication of anesthesia does occur, a dental consultation should be obtained as soon as possible. Also, the chief of the anesthesia department, the hospital’s risk manager, and the patient’s family should be notified. Patients old enough to understand what has transpired should also be informed.

The neonate is not immune from the dental complications of anesthesia. Laryngoscopy of the neonatal oral cavity may result in excoriation or laceration of the gum pads. Unilateral right- or left-sided hypoplastic enamel defects may be seen in the primary maxillary incisors as a result of laryngoscopy during the neonatal period (Angelos et al., 1989). Oropharyngeal airways, as well as suction devices, may also cause lacerations or excoriation of the intraoral soft tissues. Prophylactic use of water-soluble lubricants or saline solution applied to any of these devices before their placement reduces the likelihood of intraoral trauma.

Many children and their parents are aware of loose primary teeth during the preoperative visit. However, a careful examination, including a mobility check of each primary tooth before induction of general anesthesia, is appropriate (Maxwell et al., 1994).

If an excessively loose primary tooth is noted during the exfoliative phase, the parents should be informed, and it may be safely removed by the anesthesiologist once general anesthesia has been induced. In this increasingly litigious society, a separate, written consent may be necessary for removal of the loose primary tooth by the anesthesiologist. A gauze barrier is placed lingually to prevent inadvertent introduction of the tooth into more distal locations in the respiratory or gastrointestinal tract. Subsequently, a second gauze is wrapped around the loose tooth to be extracted. With a twisting and snapping action, the tooth is easily removed. The tooth is usually missing most or all of its root structure. The reason for the root structure loss is the natural resorptive processes that occur from the underlying permanent tooth that is beginning to erupt. If some of the root structure remains in the extraction site, no attempt should be made to retrieve it. The retrieval process may cause damage to the erupting permanent tooth bud. Also, the remaining root fragment naturally and harmlessly sequesters into the oral cavity (Herlich et al., 1996).

Conditions that may predispose the pediatric patient to dental avulsions under general anesthetic conditions include the scissors-like action of the anesthesiologist’s fingers in the mouth opening before laryngoscopy. If this maneuver is accomplished using the incisors, the likelihood of inadvertent avulsion is increased. The mouth-opening maneuvers should be accomplished by using the molars whenever possible to take advantage of their inherent dental stability as well as to effect the largest opening possible. The use of oropharyngeal airways in the pediatric or adult patient as a bite block should be avoided for similar reasons. The anterior teeth are single rooted. If the patient closes the mouth with excessive force, the force transmitted by the tooth is essentially perpendicular to the airway and leads to increased risk of avulsion or fracture. The ideal technique uses gauze bite blocks with a long retrieval tag placed along the molar teeth. The forces are now directed toward softer material and the multirooted molar teeth, which are more likely to sustain and evenly disperse the vertical, shear forces (Herlich, 1990; Herlich et al., 1996).

The inadvertent avulsion of loose primary teeth may nevertheless be unavoidable during airway manipulations. If a primary tooth is avulsed, it is imperative that it be retrieved. The tooth is usually found elsewhere in the mouth or outside of the oral cavity. It may also be found on the patient’s gown or bed sheets or on the floor. If it cannot be located in these likely places, anteroposterior and lateral thoracoabdominal radiographs are necessary to locate the tooth. If the tooth is found in the digestive tract, it should pass without incident within several days. If the tooth is found in the tracheobronchial tree, however, it must be retrieved by whatever means necessary, including thoracotomy. The sequelae of leaving a foreign body in the tracheobronchial tree are extremely dangerous (Herlich, 1990; Herlich et al., 1996).

If a primary tooth was lost and then retrieved, it should not be reimplanted. Such attempts are usually futile because of its advanced root resorption before exfoliation. Reimplantation of a primary tooth may also cause significant damage to the underlying permanent tooth bud. However, if the avulsed tooth is a permanent tooth and morphologically intact, attempts should be made to reimplant it as soon as possible. The success of dental reimplantation depends on early reimplantation. Because the periodontal ligament has remnants attached to the tooth that are crucial to the success of reimplantation, the avulsed tooth should not be scrubbed with any material. Ideal preparation consists of gentle rinsing of the tooth in cool physiologic saline solution to remove crude debris and gross clots. Then the tooth should be placed in a cool saline-soaked gauze pad until a dentist can reimplant it, either in the operating room or as early as possible during the postoperative period.

Reimplantation also includes splinting of the tooth to one or two adjacent teeth on each side of the reimplanted tooth to confer stability. Despite early reimplantation, failures exist and may necessitate root canal therapy or extraction at an unspecified later date. The time course of reimplantation failure is unpredictable (Herlich, 1990), but if reimplantation occurs within 30 minutes, success may be as high as 90% (Kainuma et al., 1996).

Pediatric dentistry has made many advances to conserve tooth structure and space if deciduous teeth are lost prematurely. Various polymer and metal crown structures may be bonded or cemented in place. Normal intraoral forces or untoward unnatural forces may cause these prosthetic devices to be loosened or avulsed during airway manipulations. For the most part, they may be easily recemented or bonded postoperatively. Most hospital dental consultants are able to rebond or recement these prostheses in place without difficulty.

Interceptive orthodontic appliances, such as mandibular lingual arch wires or maxillary segmental orthodontic wires, or both, are bonded by brackets to the teeth. These appliances may become loosened or avulsed during airway maneuvers. Like other prosthetic devices, they may also be recemented or bonded postoperatively with little harm to the patient or dentition (Herlich, 1990).

In general, a thorough preoperative history and examination and prudent warnings to the parent reduce dissatisfaction when inadvertent dental complications do occur. Congenital craniofacial anomalies, such as palatal clefts, mandibulofacial dysostosis (Treacher Collins syndrome), Pierre Robin sequence, and hemifacial microsomia, may indeed increase the likelihood of dental complications because of intubation difficulties. Congenital dental anomalies, such as amelogenesis imperfecta or dentinogenesis imperfecta, may subject the patient to dental fracture with even the most trivial airway manipulations.

Acquired dental problems, such as milk-bottle caries syndrome, occur on the lingual surfaces of teeth in children who are regularly put to bed with a bottle of milk, formula, or glucose water. These carious lesions tend to require extensive pediatric dental rehabilitation in very young patients for whom prolonged dental visits are not feasible. As mentioned, those lesions may also be subject to the dental complications of anesthesia.

Pharmacologic agents such as oncologic chemotherapy, chronic inhaled or systemic steroids, diphenylhydantoin, and nifedipine may also cause intraoral or dental damage. A child with a blood dyscrasia or one who has had head and neck radiotherapy may also be subject to dental complications of anesthesia. Blood dyscrasias predispose the child to increased intraoral hemorrhage even during daily oral hygiene activities such as tooth brushing.

Head and neck radiation result in significant xerostomia (dry mouth) because of the destruction of the salivary glands. Because normal salivary flow has been eliminated, these children are at a very high risk for cervical (gumline) caries and possible dental complications during anesthesia. Regardless of the severity or nature of the injury, any head, neck, and oral trauma may predispose a patient to dental complications of anesthesia. With proper planning and care, the patient will have fewer and less severe dental complications (Herlich et al., 1996).