Immediate (Early) Malocclusion after Sagittal Split Ramus Osteotomies

An immediate (early) malocclusion that is recognized either intraoperatively or soon after surgery (i.e., during the first several days or weeks afterward) will occur after sagittal split ramus osteotomies of the mandible unless each of the following intraoperative conditions is met* (Figs. 17-1 through 17-4):

Late Malocclusion after Sagittal Split Ramus Osteotomies

Malocclusion after the successful initial healing of sagittal split ramus osteotomies is the result of either skeletal or dental causes.* Skeletal causes may include condylar resorption (see Chapter 36); remodeling or malunion (i.e., relapse) at the osteotomy site; or continued mandibular growth; these conditions are all described in more detail later in this chapter. Dental causes of malocclusion after sagittal split ramus osteotomies are often not appreciated until much later, but they are generally related to the unstable orthodontic positioning of the teeth outside of the boundaries of the alveolar process before or after surgery; this is discussed later in this chapter (see also Chapters 5 and 6).²⁰⁸

Immediate (Early) Malocclusion after Le Fort I Osteotomy

Immediate (early) malocclusion that is recognized either intraoperatively or during the first several days or weeks after surgery may occur after a Le Fort I osteotomy unless the following intraoperative conditions are met (see Figs. 17-1 through Fig 17-4)*:

Late Malocclusion after Le Fort I Osteotomy

Skeletal causes of a late malocclusion after Le Fort I osteotomy may include the following: 1) remodeling (relapse) at the Le Fort I osteotomy site (as described later in this chapter) 2) fibrous union at the Le Fort I osteotomy site (as described later in this chapter) 3) remodeling (relapse) at the segmental osteotomy sites (as described later in this chapter) 4) condylar resorption (as described previously in this chapter and in Chapter 36)¹⁴³ and 5) continued mandibular growth (as described previously in this chapter; see Figs. 17-6 and 17-7).* Dental causes of malocclusion after Le Fort I osteotomy are often not realized until much later. They are related to the unstable orthodontic positioning of the teeth outside of the boundaries of the alveolar process before or after surgery (as described later in this chapter and in Chapters 5 and 6).²⁰⁸

The precise cause of relapse at the Le Fort I osteotomy site is often difficult to pinpoint, but it is generally related to the following: 1) inadequate mobilization of the down-fractured maxilla before the placement of fixation 2) inadequate bone contact across the osteotomy site after the fixation is applied 3) inadequate (non-rigid) plate and screw fixation across the osteotomy site or 4) excessive occlusal forces or movement transmitted across the osteotomy site during initial healing.^†

Fibrous union of the maxilla after Le Fort I osteotomy is an infrequent occurence. When it occurs, expect to find painless mobility of the upper jaw, with or without malocclusion. Risk factors should be recognized, at which point surgical techniques and postoperative management can be adjusted to limit this complication (see Fig. 16-21). The combination of extensive horizontal advancement and vertical lengthening will result in large osteotomy site defects with limited bone contact. Failure to form adequate bony bridges at the healing sites is likely to result in delayed healing, fibrous union, or late relapse. Negative influences on bone healing at the Le Fort I osteotomy site may include the following: (1) injury to flap circulation (2) thin osteoporotic bone at the zygomatic buttress and the pyriform rims, with inadequate fixation and (3) the decision to not place interpositional grafts when the bone gaps are of critical size. Additional postoperative healing risk factors include the following: (1) infection or wound dehiscence after surgery (2) the presence of a heavy occlusion (e.g., grinding, clenching) (3) too rapid of a return to normal chewing forces (4) excessive mouth opening against intermaxillary elastics and (5) the breakage (stress fracture) of the fixation plates. Systemic conditions that are known risk factors for poor bone healing include the following: (1) diabetes (2) collagen disease (3) vascular disease (4) osteoporosis or bisphosphonate use (5) nicotine abuse (6) poor nutritional status; and (7) previous radiation treatment.

Relapse across the segmental maxillary osteotomy sites after palatal widening is generally related to the following: (1) inadequate mobilization of the segments (2) inadequate surgical splinting of the new arch shape during initial healing (i.e., the first 5 weeks) (3) inadequate or unstable interdigitating occlusion between the maxillary and mandibular teeth after the splint is removed or (4) inadequate medium-term orthodontic maintenance (i.e., lasting approximately 6 months) with an appropriate appliance after the surgical splint is removed (see Figs. 17-3 and 17-8). Transverse relapse after the removal of the surgical splint may also occur as a result of the use of counterproductive intermaxillary elastic forces. For example, the use of vertical elastics placed on the buccal brackets of the upper and lower molars in an attempt to close posterior open bites may result in the simultaneous unintended collapse of the arch width.

Frequent technical errors that can occur when completing Le Fort I segmental arch expansion and that may result in malocclusion include the following:

Extraction Therapy to Eliminate Crowding

Dental extractions may be necessary when there is inadequate alveolar bone to eliminate the dental crowding and to remove compensations without displacing the roots outside of alveolar housing. Opinions regarding the indications for extractions have changed remarkably over the past 150 years since the beginning of “modern” orthodontics.

During the 1880s, Edward Angle joined other progressive restorative dentists of his time in their opposition to a casual attitude toward the extraction of teeth (see Chapter 2). Angle’s belief was that, through diligent effort, the orthodontic alignment of the full complement of teeth was possible. He felt that the orthodontist’s ultimate objective was for every person to have the potential for an ideal relationship of all 32 natural teeth.

Dr. Angle believed that the cause of most Class II or Class III problems was often the result of abnormal stresses on the jaws. Through the orthodontist’s active application of controlled pressure on the teeth (i.e., arch expansion) and occasionally directly on the bone (i.e., chin cup and headgear), Dr. Angle believed (at least early during his career) that the clinician could change jaw growth and overcome the presenting Class II or Class III deformity.

Angle also taught that proper jaw and dental function on the part of the individual should maintain the teeth in their orthodontically corrected position. He believed—or at least hoped—that, after the teeth were placed in proper occlusion, the natural forces transmitted to the teeth would cause alveolar bone to generate around them.

Through trial and error, he realized that simply tipping the teeth into a new position was often inadequate. He developed the Ribbon Arch appliance and then the Edgewise appliance to “bodily” move the teeth. These were the first clearly described and reliably designed orthodontic appliances that were capable of controlling root position. At this time, Dr. Angle claimed that these were “bone-growing appliances.”¹⁰ For Angle, this work was simply an extension of Wolff’s law of bone, which states that the internal architecture of a bone represents the stress pattern that is placed on it.

Angle’s treatment philosophy involved arch expansion with the use of vectored rubber bands and other appliances, as needed, to bring the teeth into occlusion. To Angle, at least early during his career, the term relapse as it applied after orthodontic expansion that had been carried out to uncrowd and correct overjet or overbite simply meant that the achieved occlusion was inadequate or technically incorrect. According to Angle, “If a correct occlusion had been produced [by the orthodontist] the result would be stable.”¹⁰ Therefore, he felt, “if the orthodontic result was not stable, the fault was either that of the orthodontist or poor compliance by the treated patient, not the theory.”¹⁰

For the most part, Angle believed that, for each individual, ideal facial aesthetics would result when the teeth were placed in ideal occlusion. Whether the patient agreed or not, by divine definition, the best facial appearance for that patient would be achieved when the dental arches had been expanded so that all of the teeth were in ideal occlusion. Angle adamantly believed that extractions were not indicated.

Calvin Case, who was a prominent contemporary and outspoken critic of Angle, used contouring appliances and light rubber bands to move the teeth. He argued that, although the arches could be expanded and the teeth aligned, in the long term, occlusal stability was not always satisfactory, and facial aesthetics could be compromised.

By around 1915, Case had worked out most of the mechanical principles required for the successful management of orthodontic extraction sites. With the use of full-banded appliances, he was able to routinely retract the anterior teeth into the bicuspid extraction sites to correct the inclination of the anterior teeth and to eliminate crowding. Interestingly, only about 10% of his patients were treated with extractions.

Debate in dental circles regarding the issue of extractions continued between Angle’s disciples and Case’s followers throughout the 1920s. The Dewey–Case “Great Extraction Debate” took place in 1911. Angle’s non-extraction/arch expansion approach continued to predominate with the everyday practitioner until after World War II. Angle’s philosophy was widely accepted as a result of his well-written and popular textbook; his abilities as a teacher and lecturer; his consistent treatment philosophy; and his success as a diligent clinician.

By the late 1930s, when non-extraction treatment was used on all comers, relapse was a frequent observation that could no longer be ignored. After Angle’s death, his student Charles Tweed began re-treating a number of Angle’s patients who had experienced relapse. Tweed’s retreatment approach included four bicuspid extractions followed by the realignment of the remaining dentition. He observed greater occlusal stability with this approach. By the mid-1940s, Tweed’s well-documented series of cases involving four premolar extractions with orthodontic retraction caused a revolution in orthodontic thinking that led to widespread extraction therapy in everyday orthodontic practice. Interestingly, Raymond Begg, who was another of Angle’s students and who was at this time halfway around the world in Australia, also concluded that non-extraction treatment was frequently unstable. Like Tweed, Begg modified the Angle-designed Edgewise appliance into what he called the “Begg appliance” for use with extraction therapy.

The acceptance of extraction therapy in orthodontics to stably position the teeth into alveolar housing coincided with an appreciation that genetic variations—with disparities between tooth root volume and jaw size—are common among normal individuals and will differ among races (see Chapter 3). That a presenting jaw or dental discrepancy could benefit from extractions was simply an admission of a patient’s individuality rather than the orthodontist’s inability to solve all problems in the same way. By the early 1960s, approximately 50% of American patients who were undergoing orthodontic treatment would experience the extraction of at least some teeth, most commonly the first premolars.

Orthodontists have also used extractions as a means to achieve a neutralized occlusion in the presence of a skeletal discrepancy (i.e., a camouflage approach). This involves achieving an improved occlusion while accepting the jaw (facial) disharmony. Examples of this approach include upper bicuspid extractions to orthodontically treat mandibular retrognathism or lower bicuspid extractions to orthodontically manage Class III skeletal patterns. Interestingly, this orthodontic camouflage approach became common practice during the 20th century, despite the fact that, by the early 1900s, mandibular surgery had been performed for both Class II and Class III skeletal deformities. In reality, corrective jaw surgery was rarely considered an option (except by a handful of orthodontists and surgeons) until the later decades of the 20th century (see Chapter 2).

By the 1990s, overemphasis on four bicuspid extractions as part of routine orthodontic treatment began to wane in favor of a more discriminating approach. The rationale for selective extractions as part of a comprehensive surgical and orthodontic approach has now been confirmed to be effective for the removal of dental compensation. Extraction orthodontic therapy in combination with jaw osteotomies to correct the occlusion, for long-term periodontal health, to improve the upper airway, and to enhance facial aesthetics is now considered routine for many patients. The interproximal reduction of enamel as an alternative to extractions was popularized by Dr. J. Sheridan during the 1990s. In borderline cases, it has been found to provide the necessary space for incisor uprighting (see Chapters 5 and 6).

Research confirms that clinicians and the general public prefer a face with full midface projection and with prominent teeth and lips.231,257,261 The “flat face” orthodontic standards of Tweed, which were typical during the 1950s and the 1960s, retracted rather than expanded (i.e., filled out) the face. In borderline cases, the patient’s facial appearance is generally judged as being better without extractions. The decision to extract should be viewed in the light of attaining Andrews’ Six Keys to Normal Occlusion and Six Elements of Orofacial Harmony (see Chapter 2). The primary goals are to achieve: (1) the placement of teeth solidly in the alveolar bone (2) ideal dental alignment within and between the arches and (3) the adequate position and projection of the maxillomandibular complex (i.e. facial harmony). If jaw surgery (with or without extractions) is required to achieve these objectives, it should be incorporated into the treatment plan from the outset for the benefit of the patient.

An alternative to the extraction of teeth for the relief of crowding in the maxilla is to expand the volume of the alveolar ridge. This may be accomplished via one of three techniques: (1) rapid palatal expansion (RPE) with the use of a transpalatal appliance if the palatal suture is open (i.e., 0.5 mm of widening per day); (2) surgically assisted rapid palatal expansion (SARPE) followed by transpalatal appliance widening (i.e., 0.5 mm of widening per day); (3) segmental maxillary osteotomies (i.e., Le Fort I down-fracture and full disimpaction) with immediate repositioning to correct the arch form. These three options are not equally appropriate for each individual patient. The level of success of each of these options will be dependent on the clinical circumstances.

Orthodontic Treatment of Specific Dentofacial Growth Patterns: Dental Stability and Relapse

Background

The orthodontic management of isolated transverse maxillary deficiency in children and adolescents with an open palatal suture by rapid palatal expansion (RPE) and conventional orthodontic techniques is generally possible, although stability can be troublesome.* In the non-growing individual, if standard orthodontic techniques are used for expansion beyond a few millimeters, they will produce either buccal tipping of the maxillary molars or lingual tipping of the mandibular molars with an unstable long-term occlusion and the potential for injury to the periodontium. The molars will likely relapse palatally, thereby causing clockwise rotation of the mandible with recurrent anterior open bite.

The literature confirms that a transverse maxillary deficiency that presents after palatal suture closure (i.e., an age of >14 years) should be managed surgically.* This can be done with either “surgical assistance” followed by rapid expansion using an in-place palatal appliance (the process known as surgically assisted rapid palatal expansion [SARPE]) and then orthodontic realignment or by segmental Le Fort I maxillary osteotomies in conjunction with standard orthodontics. The latter approach is carried out when clinically indicated as a one-stage procedure in combination with vertical, horizontal, and other needed surgical repositioning of the maxilla (these two approaches are discussed in more detail later in this chapter). The magnitude of segmental maxillary expansion that a surgeon is comfortable achieving is dependent on that clinician’s experience and the unique aspects of the specific patient’s palatal anatomy.

Proffit and colleagues reported that individuals who are seeking evaluation for orthognathic surgery have a 30% incidence of transverse jaw discrepancies.²⁵² True (absolute) transverse discrepancy exists when one or both of the posterior maxillary segments are in a crossbite when the casts are placed into a normal overjet and overbite position after the relief of dental compensation. This will tend to unmask arch-width discrepancies in patients with Class II malocclusions and correct a percentage of those in patients with Class III malocclusions. True transverse arch discrepancies are frequently seen in patients with 1) Class II retrognathic mandibles 2) long face Class II anterior open bites 3) those with previous thumb-sucking habits resulting in anterior open bite and 4) patients with cleft palates and maxillary deficiency.

Vanarsdall and colleagues have defined transverse skeletal discrepancies through measurements that are made on posteroanterior cephalometric radiographs.³¹⁴ The authors measured maxillary (skeletal) width from the jugular point on one side to the jugular point on the other side. They compared this measurement to the skeletal lower arch width measured from the antegonial notch on one side to the antegonial notch on the other side. From these two measurements, the determination of a differential index can be made. These researchers suggested that a preferred differential index should be approximately 20 mm in the adult Caucasian individual. Preadolescent patients will normally have a lower differential index. The authors believe that an adult with a differential of 30 mm has a significant transverse problem. According to Vanarsdall and colleagues, a differential index that varies by more than 5 mm from these values requires correction in the maxilla to establish a long-term stable occlusion and satisfactory periodontal health.³¹⁴ With the advent of three-dimensional cone beam computed tomography imaging, the more accurate measurement of the transverse maxillary width is likely available. Further research is required to confirm normal values for maxillary and mandibular arch width.

Gingival recession in any given individual is likely to have multifactorial causes. Tooth position within the alveolar process is an important factor, especially in the patient who is biologically susceptible to recession (i.e., with limited attached gingiva; see Chapters 5 and 6). According to Vanarsdall and colleagues, the most common risk factors for the gingival recession of the maxillary posterior dentition include 1) friable attached gingiva 2) genetic factors 3) emotional stress 4) inadequate labial bone and 5) buccally tipped maxillary posterior teeth (i.e., dental compensation).³¹⁴ These factors will cause the periodontium to “receive” rather than “transmit” forces, with likely continued bone loss and gingival recession occurring over time.

Vanarsdall and colleagues suggest that periodontal susceptibility to breakdown has a relationship to the position of the teeth within the arch and to the relationship of the opposing teeth when they are in occlusion (see Chapters 5 and 6).³¹⁴ The initial experimental work of these researchers shows a decrease in the numbers of pathogenic bacteria around the teeth after the teeth have been aligned into a more natural position (i.e., to more closely agree with Andrews’ Six Keys to Normal Occlusion). With good dental alignment, the numbers of harmful bacteria were brought below the threshold at which damage to the periodontal tissues frequently occurs. It is also believed by many clinicians that the achievement of maxillomandibular occlusal harmony (i.e., the correction of molar inclination and crossbites) tends to improve long-term dental and skeletal stability after orthognathic surgery (see Chapters 5 and 6).

History of SARPE and Segmental Osteotomies to Correct Maxillary Arch Deficiencies

The recorded history of transverse maxillary expansion dates back to the mid-1800s, when Angle reported the use of a jackscrew appliance in a 14-year-old girl to create space for a labially displaced canine.⁹ This form of arch expansion was frequently used in children, adolescents, and adults until Hass reported that, after the age of 18 years, it was not possible to open the mid-palatal arch with appliance distraction forces because of the presence of bridging bone spicules across the suture and the increased rigidity of contiguous bones.¹²⁴ It is now generally accepted that RPE without “surgical assistance” is clinically successful only until the age of approximately 14 years and in the presence of open sutures. Attempting orthopedic expansion beyond this age is likely to result in the tipping and extrusion of teeth followed by dental relapse after the removal of the appliance.

The first recorded use of “surgical separation” of a fused mid-palatal suture for the management of transverse maxillary deficiency was by Brown.49–51 Since that initial report, the clinical approach that includes the completion of maxillary osteotomies followed by orthodontic appliance expansion has continued to evolve. By the 1980s, it was recognized that a full Le Fort I osteotomy but without down-fracture—including the separation of the nasal septum from the maxilla and the separation of both pterygomaxillary sutures—in combination with a parasagittal palatal and interdental osteotomy (generally between the incisors) was required. The immediate activation of an in-place palatal expander in the operating room to verify the completion of the osteotomies is also required to confirm the reliability of postoperative skeletal expansion.

By the 1970s, the biologic safety of a Le Fort I osteotomy in segments and the ability to then three-dimensionally reconfigure the segments directly in the operating room without the need for post surgical orthodontic expansion was proven in experimental primate studies and through successful use in clinical practice (see Chapter 2). This led to questions about the value of SARPE as a first-stage procedure for the patient with a dentofacial deformity who also requires maxillary horizontal and vertical adjustments.

Interestingly, it is estimated that only a limited percentage of dentofacial deformity patients have a transverse interarch disharmony in isolation. Arch-width narrowing is generally associated with other maxillary discrepancies (e.g., vertical, horizontal, dental midline to facial midline, occlusal plane, and cant), and it is often seen in combination with deformities of the mandible. For the limited cases in which an isolated maxillary transverse deficiency does occur, the use of SARPE followed by orthodontic alignment makes intuitive sense.

For the patient to undergo a two-stage orthognathic surgical approach (i.e., first-stage SARPE followed by definitive orthognathic surgery 6 to 12 months later) for the management of a multivector maxillary deformity, significant value would have to be demonstrated. Variables to consider include the following: (1) the potential for intraoperative and postoperative complications (2) the risks of multiple rounds of general anesthesia and multiple recovery periods (3) the direct financial costs to the patient, to his or her family, and to the health care system (4) the necessary patient and family time commitment (5) the facial aesthetic effects and (6) the potential for relapse and the stability of the occlusion. Most clinicians agree that the single-stage approach (i.e., Le Fort I osteotomy in segments) has clear advantages when considering each of these variables, except for differences of opinion related to potential relapse and the stability of the occlusion. The patient described in Figure 17-13 could be considered a case that would cause one to favor a two-stage approach, because the end result is favorable. However, in retrospect, the family and the treating clinicians viewed this case as involving an inefficient approach to the correction of the individual’s presenting dentofacial deformity. The two-stage approach required 1) two separate general anesthetics and recoveries 2) an extended and more elaborate course of orthodontics; and 3) an increased financial burden to the family in the form of additional surgeon and hospital fees. Also, The SARPE procedure resulted in a degree of root resorption, and the Le Fort I osteotomy (Stage II) was made more difficult by the earlier SARPE procedure (Stage I). The intraoperative view (see Figure 17-13, F) shows the resulting fenestrated maxillary walls after the SARPE procedure.

Complications of the SARPE Procedure: Review of the Literature

Although SARPE is a commonly considered procedure, the prevalence of postoperative complications and suboptimal results is not insignificant.57,72,175,177,182,195,211,254,291,315,329 Williams and colleagues examined the prevalence of complications among patients undergoing SARPE.³²⁹ This was a retrospective evaluation conducted on all individuals who underwent SARPE over a 4-year timeframe (2004 to 2008) at a single institution. The study sample (n = 120) included patients with a median age of 29.5 years (range, 22 to 39 years) and was comprised of 51.7% women. Postoperative complications were divided into two main categories: surgical and dental. Thirty-three patients (28%) developed surgical complications and 18 patients (15%) developed dental or periodontal problems. Asymmetric or inadequate expansion was the most frequent surgical complication, and it was found in 13.3% (16 out of 120 patients) of the study cohort. Dental or periodontal problems—including central incisor discoloration, gingival recession, and periodontal bone loss—occurred in 15% of the cohort. Two patients developed catastrophic bone defects with associated loss of the central incisors as a result of eccentric midline osteotomies followed by infections. The study confirms that major complications after SARPE are rare, whereas the incidences of asymmetric and inadequate expansion as well as dental or periodontal problems are not insignificant. These findings confirm that the SARPE procedure should not be considered as a risk-free alternative to segmental Le Fort I osteotomies.

Verlinden and colleagues reported on a large case series of individuals (n = 73 patients) undergoing SARPE with a bone-borne appliance.³¹⁵ Although most of the problems documented were related to hardware, six patients (8%) required additional surgery for the correction of an unstable occlusion or for asymmetric expansion. Among those study patients who were followed for more than 6 months, gingival recession, periodontal bone loss, a lack of interdental bone fill, and external apical root resorption were seen in more than one third of cases. Seitz and colleagues studied patients who were undergoing SARPE (n = 22) and found that asymmetric expansion was the most frequent surgical complication. In another review of SARPE complications, Carmen and colleagues reported a 28.5% incidence of significant gingival recession.⁵⁷

Occlusal Stability and Relapse: Comparing SARPE versus Segmental Le Fort I Osteotomy

When it comes to a single-stage procedure versus a two-stage approach to the management of a complex maxillary deformity, the key aspect of occlusal stability and relapse has been reviewed in the literature and argued by clinical proponents on each side. Shortcomings in the study design of most published research add to the lack of clarity. Most studies have involved only dental casts or direct measurements of dental arch dimensions. Without the use of posteroanterior (PA) cephalograms, skeletal change cannot be differentiated from tooth movement. Another shortcoming is that most studies measure stability from the end of orthodontic treatment rather than from the point of maximum expansion. The clinical practice of over-expanding the arch to end up with a satisfactory occlusion at the end of treatment results in the underestimation of the actual relapse. With limited data points, most studies cannot differentiate skeletal relapse components from dental ones. One exception is the study by Byloff and Mossaz, which overcame these limitations by using pre-expansion and postexpansion PA cephalograms and dental casts as data points.⁵⁶ After SARPE, the authors observed a mean maximum expansion at the first molar of 8.7 mm, with an average of 36% (3.1 mm) relapse at the time of debanding. Only 1.3 mm (23%) of this relapse was felt to be skeletal, with the rest (77%) being dental. Berger and colleagues also used an improved study design and reported an average of 2.49 mm (48%) of skeletal expansion in combination with 2.4 mm (52%) of dental expansion for their patients when using a SARPE approach.³¹ Two published meta studies, which were carried out in 2005 by Koudstaal and colleagues¹⁶⁷ and in 2006 by Lagravere and colleagues,¹⁷⁶ both concluded that, until that time, no good evidence existed regarding the amount of relapse after SARPE.

Chamberland and Proffit studied this controversy, and, in 2008, they published their initial research.⁵⁹ They continued to follow their patients for the long term, and they also added numbers to the study group (N = 38). Their study has been recognized for adding significant clarity to this important subject and is therefore reviewed in the next section of this chapter.

Skeletal Stability and Relapse of SARPE: Review of a Benchmark Study

A prospective observational study was carried out by Chamberland and Proffit to review the SARPE outcomes in 38 consecutive patients between the ages of 15 and 54 years, with an observation period that extended to 2 years after the completion of treatment.⁶⁰ The data collected by these authors included measurements taken from both dental casts and PA cephalograms at the following specific time intervals:

All study patients had a transverse discrepancy of 5 mm or more and were beyond the level of maturity at which palatal expansion without surgery would be possible. The surgical technique involved all bone cuts required for a Le Fort I osteotomy, including the separation of the pterygoid junctions, the nasal septum, and the mid-palatal suture as well as an osteotomy between the central incisors. During surgery, the expansion device was activated to achieve a 1- to 1.5-mm separation of the maxillary central incisors. After latency (7 days), the device was activated twice daily (0.5 mm/day). The patients were monitored twice weekly until the planned expansion was achieved 12 to 20 days later. All patients were expanded 2 mm beyond the desired final position. The expansion device was kept in place for approximately 6 months after the completion of orthodontic goals.

Interestingly, the research data confirm that almost the entire measured relapse was dental rather than skeletal. At 49 months after the SARPE procedure, the maintained expansion at the first molars had relapsed to approach the skeletal expansion (i.e., 4.6 mm total molar expansion [dental and skeletal] as compared with 3.6 mm skeletal expansion). The skeletal expansion that was measured at both the jugula and the nasal cavity was statistically stable.

All patients were maximally expanded 2 mm beyond the desired final position on the basis of the researchers’ assumptions that a degree of relapse was inevitable. This overcorrection ensured that, despite a measured dental relapse of 30%, none of the patients showed posterior crossbite at the completion of treatment. One can conclude that, despite retention attempts, over the long term the teeth drift back into the basal bone (see Chapters 5 and 6).

The authors also compared their relapse and stability results with other published SARPE studies. Their measured 30% relapse rate was found to be less than the 36% relapse reported by Byloff and Mossaz.⁵⁶ Alternatively, their 30% documented relapse rate was higher than that reported by either Berger and colleagues³¹ or Pogrel and colleagues.²³⁸ As previously stated, most SARPE studies—including these two—do not report relapse from a starting point of maximal expansion. However, not doing so will underestimate the level of actual relapse and may explain the differences reported.

Chamberland and Profit showed that, when a SARPE procedure is carried out with the use of optimal surgical and orthodontic techniques, maxillary expansion that is about 47% skeletal and 53% dental can be expected.59,60 The skeletal expansion that occurred with SARPE followed by strict orthodontic maintenance mechanics for approximately 5 months proved to be statistically stable. The overall relapse rate (30%) was almost totally attributable to lingual retraction (dental relapse) of the posterior teeth. As stated, the authors recommend a 2-mm excess expansion in anticipation of dental relapse. For example, in the case of a desired 8-mm first molar expansion, 10 mm of surgical expansion at the molars is recommended. The researchers documented the advantage of compensating for the inevitable buccal tipping of the posterior maxillary teeth during the expansion phase followed by an inevitable lingual dental relapse after the device is removed. Approximately 25% of their patients had more than 3 mm of dental relapse, whereas 42% had between 1 mm and 3 mm. A full 66% of patients experienced more than 2 mm of dental relapse over the long term (i.e., 2 years after debonding).

Stability and Relapse: Comparing SARPE in Adults versus RPE in Prepubertal Children

The literature confirms that, in the prepubertal child or the adolescent with an open palatal suture, a loss of about one third of the maximum expansion occurs across the first molars after non-surgical RPE. PA cephalograms performed for prepubertal patients with palatal implant markers who underwent RPE demonstrate that approximately 50% of the expansion achieved is skeletal, with the remainder being dental. This can be compared to Chamberland and Proffit’s adult SARPE data.59,60 Those authors demonstrated a mean of 3.47 mm of skeletal expansion and 2.25 mm of dental expansion (i.e., 5.12 mm of total expansion) at the first molars. They then documented a 30% relapse, the majority of which was dental. Therefore, a comparable 30% overall relapse in both the SARPE (adult) group and the RPE (prepubertal) group was found to occur. Interestingly, in the SARPE group, the maintenance of skeletal expansion was greater than that achieved in the RPE group.

Stability and Relapse in Adults: Comparing SARPE versus Segmental Le Fort I Osteotomies

The best data regarding stability after transverse expansion with segmental Le Fort I osteotomies were reported for 32 patients by Phillips and colleagues.²¹⁵ Chamberland and Proffit compared the segmental Le Fort I osteotomy group of Phillips and colleagues to their SARPE study patients.^59,60 They used a subgroup of Phillips and colleagues’ patients who had undergone levels of maxillary expansion that were equivalent to those of their own SARPE patients. A comparison of the findings demonstrated the following: 1) the mean relapse across the first molars was greater for the Le Fort I group, but the difference was not statistically significant; and 2) the mean relapse across the canines was greater for the SARPE group and was statistically significant.

With reference to the SARPE (two-stage) approach versus the Le Fort I segmental (single-stage) approach for the correction of complex maxillary deformities (i.e. combination of arch-width, vertical, and horizontal deformities), the author’s conclude:59,60

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