Long-term stability of surgical open-bite correction by Le Fort I osteotomy

Posttreatment stability of an anterior open-bite by molar intrusion compared with 2-jaw surgery - a retrospective study

OBJECTIVES

This study aimed to compare post-treatment stability in patients with anterior open-bite (AOB) between those treated surgically (orthognathic 2-jaw surgery) and non-surgically (molar intrusion using orthodontic miniscrews).

MATERIALS AND METHODS

All subjects had initial overbite (OB) < -1 mm and lateral cephalograms taken before treatment (T0), immediately after AOB correction (T1), after orthodontic treatment (T2), and at least 1 year after treatment (T3). The non-surgical group was enrolled retrospectively; then, the surgical group was matched by OB, sex, and age to the non-surgical group (n = 21 each). Changes in cephalometric measurements during treatment (T1-T0), finishing (T2-T1), and retention (T3-T2) periods were compared between two groups.

RESULTS

OB increased by 4.5-5.1 mm during the treatment period with 3.3 mm upward movement of the maxillary first molar (U6) in both groups. Changes in OB were not significantly different between the groups: 0.5-0.9 mm increase during the finishing period but 1.0 mm decrease during the retention period (P > 0.05). U6 moved 0.5 mm downward in non-surgical group and 0.1 mm upward in the surgical group during the finishing period, and 1.0 mm and 0.4 mm downward in the non-surgical and surgical groups, respectively, during the retention period.

CONCLUSIONS

Post-treatment stability of AOB was similar for surgical and non-surgical methods (76.8 - 78.7%), although U6 moved more downward in the non-surgical group than in the surgical group.

CLINICAL RELEVANCE

AOB without severe skeletal deformity can be treated by either molar intrusion or orthognathic surgery with similar treatment outcome and stability.

Outcomes and Stability of Anterior Open Bite Treatment with Skeletal Anchorage in Non-Growing Patients and Adults Compared to the Results of Orthognathic Surgery Procedures: A Systematic Review

The objective of this review is to evaluate, on the basis of the available literature, if anterior open bite (AOB) can be successfully treated with the intrusion of molar teeth using skeletal anchorage in non-growing patients and adults and if this treatment modality provides comparable results to those obtained by orthognathic surgery procedures.

METHODS

A systematic review of published data in major databases from 2000 to 2021 was performed.

RESULTS

In total, 92 articles were included in title and abstract screening, and only 16 articles (11 concerning AOB correction by molar intrusion with skeletal anchorage, and five considering AOB treatment by orthognathic surgical intervention) qualified for thorough data extraction and analysis.

CONCLUSIONS

On the basis of this review, it seems to be possible to obtain successful results for AOB treatment in non-growing patients and adults by means of the intrusion of molar teeth with skeletal anchorage. However, due to the different methods of assessing treatment outcomes used by different authors, it is not possible to state conclusively whether the treatment of AOB by means of molar intrusion with skeletal anchorage provides long-term results that are comparable to orthognathic surgery procedures.

Skeletal Class III Malocclusion with Lateral Open Bite and Facial Asymmetry Treated with Asymmetric Lower Molar Extraction and Lingual Appliance: A Case Report

A skeletal Class III malocclusion with open bite tendency is considered very difficult to treat orthodontically without surgery. This case report describes the lingual orthodontic treatment of an adult skeletal Class III patient with mandibular deviation to the left side, lateral open bite, unilateral posterior crossbite, zero overbite and negative overjet. The lower incisors were already retroclined to compensate with the skeletal discrepancy. The patient was treated by asymmetric molar extraction in the mandibular arch to retract the lower incisors and correct the dental midline, with the help of intermaxillary elastics. Lingual appliance was used with over-torqued lower anterior teeth’s brackets to control the torque of mandibular incisors. After a 30-month treatment, satisfactory smile and facial esthetics and good occlusion was achieved. A 12-month follow-up confirmed that the outcome was stable. Asymmetric molar extraction could be a viable option to retract mandibular incisors in Class III malocclusion with lower dental midline deviation.

Skeletal stability after maxillary step osteotomy compared with original Le Fort I osteotomy during one-year of follow-up

The purpose of the current study was to compare the 1-year stability of skeletal after original Le Fort I osteotomy and maxillary step osteotomy. Fifty-two patients with prognathism underwent sagittal split ramus osteotomy with either original Le Fort I osteotomy or maxillary step osteotomy (26 patients each). Twelve cephalometric parameters were measured to evaluate postsurgical stability (lesser change was considered as enhanced stability) at 1 month (T1), 6 months (T2), and 1 year (T3) postoperatively. Only 3 parameters—vertical and horizontal distance of menton and vertical distance of point B—showed minimal but significant differences between the two groups. Lesser degrees of changes were observed after maxillary step osteotomy than after original Le Fort I osteotomy, and the differences were significant during the period between T1 and T2, but not from T1 to T3. Differences between the two groups were less in asymmetry cases required correction of the occlusal plane. In conclusion, differences between original Le Fort I osteotomy and maxillary step osteotomy were observed at the frontal points of the mandible; however, they were not clinically significant. It may be suggested that there is no significant difference in skeletal stability at 1 year after the two procedures.

Botulinum toxin-A injection into the anterior belly of the digastric muscle for the prevention of post-operative open bite in class II malocclusions: a case report and literature review

Background

Class II malocclusion patients with hyperdivergent facial types are characterized by short mandibular body lengths and anterior open bite. Accordingly, the treatment for hyperdivergent skeletal class II malocclusion is a lengthening of the mandibular body length and a counterclockwise rotation of the mandible. To prevent post-operative relapse, botulinum toxin-A (BTX-A) injection can be a retention modality.

Case presentation

A class II open-bite patient received BTX-A injection to the anterior belly of her digastric muscle for the prevention of post-operative relapse. The relapse was evaluated via a clinical examination and a lateral cephalometric radiograph after the completion of post-surgical orthodontic treatment. The patient showed stable occlusion without any signs of relapse at 15 months post-operatively.

Conclusion

In this case presentation, a single injection into the anterior belly of the digastric muscle was sufficient for the prevention of post-operative open bite.

Three-dimensional analysis of condylar changes in surgical correction for open bite patients with skeletal class II and class III malocclusions

The aim of this study was to quantify three-dimensional condylar displacements as a result of two-jaw surgery for open bite correction in patients with skeletal class II and class III malocclusion. Pre-surgical (T1) and post-surgical (T2) cone beam computed tomography scans were taken for 16 patients with skeletal class II (mean age 22.3±9.47years) and 14 patients with skeletal class III (mean age 25.6±6.27years). T2 scans were registered to T1 scans at the cranial base. Translational and rotational condylar changes were calculated by x,y,z coordinates of corresponding landmarks. The directions and amounts of condylar displacement were assessed by intra- and inter-class Mann-Whitney U-test or t-test. Class II patients presented significantly greater amounts of lateral (P=0.002) and inferior (P=0.038) translation than class III patients. The magnitudes of condylar translational displacements were small for both groups. Skeletal class III patients had predominantly medial (P=0.024) and superior (P=0.047) condylar translation. Skeletal class II patients presented greater condylar counterclockwise pitch (P=0.007) than class III patients. Two-jaw surgery for the correction of open bite led to different directions and amounts of condylar rotational displacement in patients with skeletal class II compared to class III malocclusion, with greater rotational than translational displacements.

Evaluation of Long-term Stability of Vertical Control in Hyperdivergent Patients Treated with Temporary Anchorage Devices

This study aims to evaluate the long-term stability of vertical control in hyperdivergent patients treated with temporary anchorage devices. The sample included 20 hyperdivergent patients without anterior open bite. The temporary anchorage devices were used to intrude the upper incisor and molars for vertical control. Lateral cephalograms were established prior to treatment, immediately after treatment, and during retention. The upper molars and incisors were intruded by 1.33 mm and 1.41 mm after treatment (P<0.05). U6-PP increased by 0.11 mm and 0.23 mm during the first and second stages of retention (P>0.05). U1-PP was found to possess a significant extrusion of 1.2 mm during the first stage (P<0.05), which increased by 0.68 mm during the second stage (P>0.05). The mandibular plane angle (MP-SN) decreased by 2.58 degrees following treatment, and underwent a relapse of 0.51 degree and 0.42 degree during the first and second stages of retention respectively (P>0.05). No significant soft tissue changes occurred, with the exception of increased upper lip length during the second stage (P<0.05). Maxillary anterior and posterior intrusions, counter clockwise rotation of the mandibular plane, and improved profiles can be successfully achieved following treatment with vertical control. During the first stage of retention (less than three years), intruded molars and incisors both exhibited some extrusion, and molars had better long-term stability than incisors. During the second stage of retention (three to six years), the therapeutic effects appeared stable, with the exception of some increase in upper lip length. Rotated mandibular plane remained stable during the entire retention period.

Nonsurgical and nonprosthetic camouflage treatment of skeletal Class II open bite with bilaterally missing lower first molars

This report illustrates the successful nonsurgical and nonprosthetic camouflage treatment of a skeletal Class II open bite malocclusion combined with missing mandibular first molars bilaterally. In the mandible, the second and third molars were uprighted and protracted, substituting for the missing first molars. In the maxilla, anterior bodily retraction and full-arch intrusion were achieved following premolar and second molar extraction, which also induced autorotation of the mandible. The treatment outcome and prognosis were confirmed with three-dimensional superimposition techniques, along with long-term stability.

Cephalometric characteristics of postorthodontic female patients with attractive and unattractive frontal posed smiles

OBJECTIVES:

To identify differences in skeletal, dental, and soft-tissue morphology between postorthodontic patients with attractive and unattractive frontal posed smiles.

MATERIALS AND METHODS:

The attractiveness of close-up photographs of frontal posed smiles in 100 adult female patients after conventional orthodontic treatment was evaluated by 20 dental students (10 men, 10 women) using a visual analogue scale. Posttreatment cephalograms of the 20 patients with the most attractive smiles (attractive group; mean age 23.75 ± 3.35 years) and the 20 patients with least attractive smiles (unattractive group; mean age 23.11 ± 4.45 years) were selected, and 41 measurements were made and compared between groups using the Mann-Whitney U-test ( P < .05).

RESULTS:

When compared with the attractive group, the unattractive group exhibited greater values for sella-nasion plane to mandibular plane, palatal plane to mandibular plane, anterior facial height, lower facial height, and lower facial height/anterior facial height as skeletal measurements; for occlusal plane to sella-nasion plane, palatal plane to occlusal plane, and maxillary central incisor to palatal plane as dental measurements; and for lower face, upper lip length, and upper lip superior to palatal plane as soft-tissue measurements.

CONCLUSIONS:

Cephalometric analysis revealed that postorthodontic Japanese female patients with unattractive frontal posed smiles are characterized by a hyperdivergent skeletal pattern with extruded maxillary incisors and a steep occlusal plane, accompanied by a longer upper lip than patients achieving attractive posed frontal smiles.

Long-term stability of soft tissue changes in anterior open bite adults treated with zygomatic miniplate-anchored maxillary posterior intrusion

OBJECTIVES

To evaluate soft tissue changes and their long-term stability in skeletal anterior open bite adults treated by maxillary posterior teeth intrusion using zygomatic miniplates and premolar extractions.

MATERIALS AND METHODS

Lateral cephalograms of 26 patients were taken at pretreatment (T1), posttreatment (T2), 1 year posttreatment (T3), and 4 years posttreatment (T4).

RESULTS

At the end of treatment, the soft tissue facial height and profile convexity were reduced. The lips increased in length and thickness, with backward movement of the upper lip and forward movement of the lower lip. The total relapse rate ranged from 20.2% to 31.1%. At 4 years posttreatment, 68.9% to 79.8% of the soft tissue treatment effects were stable. The changes in the first year posttreatment accounted for approximately 70% of the total relapse.

CONCLUSIONS

Soft tissue changes following maxillary posterior teeth intrusion with zygomatic miniplates and premolar extractions appear to be stable 4 years after treatment.

Skeletal anchorage for intrusion of bimaxillary molars in a patient with skeletal open bite and temporomandibular disorders

The treatment of severe skeletal anterior open bite is extremely difficult in adults, and orthognathic surgery is generally selected for its treatment. We report the case of an 18-year-old adult patient with skeletal anterior open bite and temporomandibular disorders who was successfully treated using temporary anchorage devices. She had an open bite of −2.0 mm and an increased facial height. Miniplates were implanted in both the maxilla and mandible, and molar intrusion resulted in counterclockwise rotation of the mandible over a period of 12 months. After active treatment, her upper and lower first molars were intruded by approximately 2 mm and her overbite became +2.5 mm. Her retrognathic profile improved with counterclockwise rotation of the mandible. Orthodontic treatment aided with skeletal anchorage is beneficial for intrusion of bimaxillary molars in patients with anterior open bite.

[Evaluation for vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior open-bite]

OBJECTIVE

To evaluate vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior openbite.

METHODS

A retrospective multicenter cohort study was conducted to investigate vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior openbite. From 2010-2016, 122 patients from two domestic stomatological hospitals were included in our study. Patients were divided into four groups according to their treatment plans, namely, bilateral sagittal split ramus osteotomy (BSSRO), intraoral vertical ramus osteotomy (IVRO), BSSRO+Le Fort Ⅰ, and IVRO+Le Fort Ⅰ. All patients followed a standardized examination procedure at 6 and 24 months post-treatment. The observation indexes include overbite, mandibular plane angle, and intermaxillary angle.

RESULTS

1) The significantly reduced ratio of the overbite in the BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than the BSSRO and IVRO groups at 6 and 24 months post-treatment. 2) The significantly increased ratio of the mandibular plane in BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than BSSRO and IVRO groups at 6 and 24 months post-treatment. 3) The significantly increased ratio of the intermaxillary angles in BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than the BSSRO and IVRO groups at 6 months post-treatment, while there was no statistical difference at 24 months post-treatment.

CONCLUSIONS

Bimaxillary surgery (BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ) is more effective than mandibular surgery to control vertical relapse.

The Factors Affecting Long-Term Stability in Anterior Open-Bite Correction - A Systematic Review

Objective

The present systemic review was conducted with the main purpose to evaluate the quantitative effects of orthognathic surgeries, extraction versus non-extraction treatment, and the type of malocclusion in the stability of anterior open-bite (AOB) correction over the long-term.

Methods

The systematic search for studies was conducted through MEDLINE, CINAHL, EMBASE, Scopus, PsychINFO, various key journals, and review articles; November 30, 2016, was the last date for the search. The Quality Assessment Tool for Quantitative Studies was used to grade the methodological quality of the studies.

Results

The present review included 14 studies. Stability of the corrected AOB ranged from 61.9% to 100%. The studies with orthognathic surgeries showed a stability of 70-100%. The studies without orthognathic surgeries showed the stability of 61.9-96.7%. All of the studies were retrospective. The mean change in AOB before (T1) and after treatment (T2-T1) was 0.1 mm to 6.93 mm and the mean change in overbite from T2 to T3 (T3-T2) was -0.06 mm to 2.5 mm.

Conclusion

Studies with orthognathic surgeries presented with high amount of long-term stability in corrected AOB. No significant difference was noticed in relation to the type of malocclusion and extraction or non-extraction cases.

Morphology of open bite

OBJECTIVES

The purpose of this work was to define and illustrate the skeletal morphology of open-bite patients against the background of sagittal jaw relationships on the basis of lateral cephalograms.

MATERIALS AND METHODS

Lateral cephalograms of 197 untreated adults were analyzed in dental imaging software (Onyx Ceph 3™; Image Instruments, Chemnitz, Germany). Four groups were formed based on vertical (Index scores) and sagittal (individualized ANB values) parameters. Ninety-nine patients were defined as the control group due to their neutral sagittal and vertical relationships. The remaining patients were found by their vertical relationships to represent open-bite cases and were divided by their sagittal relationships into three study groups: neutral (Class I, n = 34), distal (Class II, n = 26), and mesial (Class III, n = 38). A geometric morphometric approach was used to analyze the x,y-coordinates of 28 skeletal landmarks on each cephalogram. Relative size was captured based on centroid size (CS). The shape-determining factors in the groups were compared by permutation testing after Procrustes transformation, and intergroup differences were visualized in the form of thin-plate splines.

RESULTS

While size (CS) was significantly increased in the Class III group, the other two groups were not different from the control group. After Procrustes transformation, characteristic and invariably significant (p < 0.001) differences in shape were detected. Neutral (Class I) open bite involved compression in the mandibular ramus and the upper anterior facial third, including vertical expansion in the lower molar and anterior nasal spine areas. Mesial (Class III) open bite was associated with pronounced vertical and sagittal size reductions in the upper posterior segments and reduced lengths of the mandibular ramus. Distal (Class II) open bite involved expansion in the pterygoid area and compression in the mandibular ramus.

CONCLUSION

Open bite is not a homogeneous group. Our geometric techniques of morphometric analysis revealed typical patterns, thus, confirming the differences observed by traditional morphometry. True skeletal overdevelopment appears to be present only in open-bite cases having a mesial jaw relationship. All open-bite groups have in common that the mandibular ramus is compressed, but marked differences are seen in terms of vertical development of the maxilla. This differentiated view of open-bite cases should be taken into consideration during individual etiology assessment and treatment planning.

Nonsurgical treatment of skeletal anterior open bite in adult patients: Posterior build-ups

OBJECTIVE

To (1) evaluate the efficacy of build-ups in the correction of anterior open bite in adults, (2) evaluate their efficacy in producing molar intrusion, (3) analyze skeletal and dental changes, and (4) assess the long-term stability.

MATERIALS AND METHODS

The sample consisted of 93 lateral cephalograms from 31 patients with skeletal and dental anterior open bite. The patients had received orthodontic treatment consisting of bonded resin blocks on the maxillary molars combined with Tip-Edge Plus bracket appliances. Cephalometric measurements were performed on radiographs taken before treatment (T1), after treatment (T2), and after a retention period (T3), which were analyzed and compared.

RESULTS

Significant dental and skeletal changes were observed after treatment. Molar intrusion averaging 1 mm; 1.44 and 1.57 mm extrusion of mandibular and maxillary incisors, respectively; and a mean of 3.98 mm overbite increase were observed. The mandibular plane angle showed a mean closure of 1.19°, and there was a mean decrease in anterior facial height of 0.7 mm. A mild relapse tendency was observed, but long-term stability was acceptable.

CONCLUSIONS

Build-ups are an effective treatment alternative for anterior open bite in adults. Outcomes remain significantly stable during the retention period.

Orthodontic and surgical perspectives in management of a severe skeletal open bite

In orthognathic correction of skeletal discrepancy, different treatment options should be considered to give optimum results to the patient with minimal postoperative problems caused by extensive bi-jaw surgery. In a case of severe vertical dysplasia with a large open bite, the orthodontist with the help of advanced diagnostic tools such as imaging software had planned bi-jaw surgery. However, there was a difference in opinion with the oral surgeon who considered only single jaw surgery to get adequate results. The possibility of only maxillary Le Fort I surgery creating autorotation of the mandible was considered, as 0.5° of autorotation results with 1° of maxillary posterior segment clockwise rotation thus avoiding bi-jaw surgery. After performing the Le Fort I superior repositioning of maxilla, the mandibular autorotation was not adequate, so a mandibular bilateral sagittal split osteotomy (BSSO) for mandibular advancement had to be performed to achieve favourable results.

Evaluation of relapse after orthodontic therapy combined with orthognathic surgery in the treatment of skeletal class III

INTRODUCTION

Multidisciplinary treatment of skeletal malocclusion by orthognathic surgery in addition to orthodontics is a routine strategy believed to offer good functional and esthetic outcomes. Postoperative relapse is, however, a problem. The present study was conducted to analyze the stability of outcomes achieved by surgical treatment of skeletal class III patients in terms of the rate and extent of relapses.

PATIENTS AND METHODS

A total of 30 patients who had undergone orthodontic treatment combined with orthognathic surgery were included. The primary inclusion criterion was a skeletal class III treated by mandibular setback (Obwegeser/Dal Pont) surgery alone or combined with maxillary advancement (Le Fort I) surgery. Analysis was based on one preoperative and two postoperative cephalograms per patient.

RESULTS

We observed relapse (defined, in accordance with Proffit, as changes >2 mm or 2°) at a rate of 24% after bimaxillary procedures, compared to a lower rate of 21% after mandibular setback procedures only. The relapse rate was 21% among patients who had undergone upper-jaw surgery versus 27% among those who had undergone lower-jaw surgery, which was statistically significant.

CONCLUSION

The majority of patients exhibited stable treatment outcomes. Maxillary advancement procedures were found to be less susceptible to relapse-resulting in more stable outcomes-and mandibular setback distances correlated positively with the degree of the relapse. No statistically significant differences were observed between the procedures conducted in both jaws versus in the lower jaw only, or in the extent of upper-jaw repositioning.

Long-term stability of surgical-orthodontic correction of class III malocclusions with long-face syndrome

Objectives: In the first place, to evaluate skeletal changes of the maxilla and mandible induced by surgical-orthodontic correction of malocclusions class III with long-face syndrome and secondly, to analyze the stability of these skeletal changes in the long term (more than 6 years). Design of Study: A retrospective, unicentric and longitudinal study of 19 patients who had undergone surgical and orthodontic therapy for class III skeletal malocclusion with long-face syndrome was undertaken. A cephalometric analysis based on 8 angle measurements, and statistical analyses at three different points in time (before orthodontic treatment, after orthognathic surgery and after a retention period of at least 6 years) were carried out. Results: The changes produced following surgery show that, with the exception of the maxillary plane and the facial axis, all other variables presented changes of great statistical difference. Conclusions: Skeletal changes after orthodontic-surgical correction present maxillary advance, mandibular regression and mandibular anterorotation. The angles that represent the mandibular vertical position (ramus angle, goniac angle and mandibular plane angle) showed statistically significant relapses and no stability in contrast to the facial axis.

Key words:Long term results, stability, relapse, orthognathic surgery, class III, long face.

Human masseter muscle fiber type properties, skeletal malocclusions, and muscle growth factor expression

PURPOSE

We identified masseter muscle fiber type property differences in subjects with dentofacial deformities.

PATIENTS AND METHODS

Samples of masseter muscle were collected from 139 young adults during mandibular osteotomy procedures to assess mean fiber areas and percent tissue occupancies for the 4 fiber types that comprise the muscle. Subjects were classified into 1 of 6 malocclusion groups based on the presence of a skeletal Class II or III sagittal dimension malocclusion and either a skeletal open, deep, or normal bite vertical dimension malocclusion. In a subpopulation, relative quantities of the muscle growth factors IGF-I and GDF-8 gene expression were quantified by real-time polymerase chain reaction.

RESULTS

Fiber properties were not different in the sagittal malocclusion groups, but were very different in the vertical malocclusion groups (P ≤ .0004). There were significant mean fiber area differences for type II (P ≤ .0004) and type neonatal-atrial (P = .001) fiber types and for fiber percent occupancy differences for both type I-II hybrid fibers and type II fibers (P ≤ .0004). Growth factor expression differed by gender for IGF-I (P = .02) and GDF-8 (P < .01). The ratio of IGF-I:GDF-8 expression associates with type I and II mean fiber areas.

CONCLUSION

Fiber type properties are very closely associated with variations in vertical growth of the face, with statistical significance for overall comparisons at P ≤ .0004. An increase in masseter muscle type II fiber mean fiber areas and percent tissue occupancies is inversely related to increases in vertical facial dimension.

Postsurgical Orthodontic Treatment Planning: a Case Report with 20 Years Follow-up

Background

Traditionally, maxillofacial deformities are corrected surgically after an initial orthodontic treatment phase. However in, this article, the authors emphasize the postsurgical therapeutic protocol which is extremely important for determining the final and permanent retention of the corrected occlusion.

Methods

A 55 year old female with severe skeletal Class II malocclusion is presented. Combined surgical and orthodontic correction of the malocclusion was used.

Results

: The step-by-step procedure the authors followed for the postsurgical therapy is described. The goals of the postoperative therapy were to restore and rehabilitate neuromuscular function, obtain occlusal stabilization, grind teeth selectively, and final occlusion retention. The importance of a surgical occlusal splint for rehabilitating stomatognathic neuromuscular function postoperatively was demonstrated. Furthermore, the orthodontic-prosthodontic treatment ensured occlusion stability after the surgical correction. The long-term results confirmed the efficacy of the treatment protocol presented here from both functional and aesthetical perspectives.

Conclusions

Postsurgical orthodontic treatment is an important step in the surgical and orthodontic therapy of maxillofacial deformities.

Three-dimensional assessment of mandibular advancement 1 year after surgery

INTRODUCTION

This prospective observational study evaluated changes in the 3-dimensional position and remodeling of the mandibular rami, condyles, and chin at splint removal and 1 year after mandibular advancement surgery.

METHODS

Presurgery, splint removal (4-6 weeks postsurgery), and 1-year postsurgery cone-beam computed tomography scans of 27 subjects were used. Superimposition on the cranial base was used to assess positional or remodeling changes in the anatomic regions of interest. Surface distance displacements were visually displayed and quantified by 3-dimensional color maps. A 1-sample t test was used to assess the average postsurgical changes of each region of interest. The level of significance was set at 0.05.

RESULTS

After antero-inferior chin displacement with surgery (mean, 6.81 +/- 3.2 mm at splint removal), the average 1-year postsurgery displacement was not statistically significant (P = 0.44). Postsurgical adaptations greater than 2 mm were observed in 48% of the patients: 16% with an additional anterior-inferior displacement of the chin of 2 to 4 mm, and 4% with >or= 4 mm; 20% had postero-superior movement of 2 to 4 mm, and 8% had postero-superior movement of >or= 4 mm. The condyles tended to move, on average, <or= 2 mm supero-posteriorly with surgery, and this small positional displacement was maintained 1 year postsurgery (right condyle, P = 0.58; left, P = 0.88). The rami exhibited outward (lateral) movements with surgery, with greater displacement of the inferior part of the rami (2 mm in 65% of the subjects). This torque of the ramus with surgery was stable 1 year postsurgery.

CONCLUSIONS

Three-dimensional assessment of skeletal changes with mandibular advancement surgery shows that nearly half of the patients have >2 mm change in chin position from splint removal to the 1-year follow-up, with approximately equal chances of anterior and posterior movement. Torque of the rami usually occurs with mandibular advancement surgery.

Assessment of mandibular advancement surgery with 3D CBCT models superimposition

OBJECTIVES: To assess surgery and short-term post-surgery changes in the position of the condyles, rami and chin after mandibular advancement. METHODOLOGY: Pre-surgery (T1), 1 week post-surgery (T2), and 6 week post-surgery (T3) CBCT scans were acquired for 20 retrognathic patients with short or normal face height. 3D models were built and superimposed through a fully automated voxel-wise method using the cranial base of the pre-surgery scan as reference. Anatomic regions of interest were selected and analyzed separately. Within-subject surface distances between T1-T2, T2-T3, and T1-T3 were computed. Color-coded maps and semi-transparent display of overlaid structures allowed the evaluation of displacement directions. RESULTS: After an antero-inferior chin displacement with surgery in all cases (>4 mm in 87.5%), 25% of the patients showed some kind of posterior movement (< 3 mm), and 69% showed an antero-superior movement after splint removal. Comparing T1-T3, an antero-inferior (87.5% of the cases) or only inferior (12.5%) displacement was observed (>4 mm in 80%). Considering all directions of displacement, the surface distance differences for the condyles and rami were small: 77.5% of the condyles moved <2 mm with surgery (T1-T2), and 90% moved <2 mm in the short-term (T2-T3) and in the total evaluation (T1-T3), while the rami showed a <3 mm change with surgery in 72.5% of the cases, and a <2 mm change in 87.5% (T2-T3) and in 82% (T1-T3). CONCLUSIONS: Expected displacements with surgery were observed and post-surgery changes suggested a short-term adaptive response toward recovery of condyle and ramus displacements. The changes on the chin following splint removal suggested an acceptable adaptation, but with considerable individual variability.

Long-term outcome of surgical Class III correction as a function of age at surgery

INTRODUCTION

In this study, we assessed whether the likelihood of a positive overjet 5 to 10 years after Class III surgery was affected by age at the surgery or the type of surgery and evaluated the amount and pattern of postsurgical growth.

METHODS

Cephalometric measurements including overjet were evaluated from immediately postsurgery and long-term recall cephalograms of 104 patients who had had surgical Class III correction and at least 5-year recalls. The patients were classified as younger (<age 18 years for females at the surgery or 20 years for males) or older and by type of surgery (maxilla only vs mandibular only or 2 jaw). For the younger patients, the timing of treatment was based largely on serial cephalometric radiographs that eventually showed minimal or no mandibular growth.

RESULTS

Long-term changes in overjet and other cephalometric characteristics in the younger and the older patients were similar. No patients in the sample had negative overjet in the long term, but zero overjet (<1 mm) was observed in some patients in all groups. Patients who had mandibular setback at any age were 2.6 times more likely to have zero overjet in the long term (P = .003) than those with maxillary surgery alone. For the younger patients, the likelihood of zero overjet in the long term was not significantly different from patients who were treated later (P = .87), with or without mandibular surgery.

CONCLUSIONS

The data support the use of serial cephalometric radiographs, with surgery deferred until little or no mandibular growth is observed, to determine the timing of Class III surgery in younger patients.

The hierarchy of stability and predictability in orthognathic surgery with rigid fixation: an update and extension

A hierarchy of stability exists among the types of surgical movements that are possible with orthognathic surgery. This report updates the hierarchy, focusing on comparison of the stability of procedures when rigid fixation is used. Two procedures not previously placed in the hierarchy now are included: correction of asymmetry is stable with rigid fixation and repositioning of the chin also is very stable. During the first post-surgical year, surgical movements in patients treated for Class II/long face problems tend to be more stable than those treated for Class III problems. Clinically relevant changes (more than 2 mm) occur in a surprisingly large percentage of orthognathic surgery patients from one to five years post-treatment, after surgical healing is complete. During the first post-surgical year, patients treated for Class II/long face problems are more stable than those treated for Class III problems; from one to five years post-treatment, some patients in both groups experience skeletal change, but the Class III patients then are more stable than the Class II/long face patients. Fewer patients exhibit long-term changes in the dental occlusion than skeletal changes, because the dentition usually adapts to the skeletal change.

Three-dimensional cone-beam computed tomography for assessment of mandibular changes after orthognathic surgery

INTRODUCTION

The purpose of this study was to assess alterations in the 3-dimensional (3D) position of the mandibular rami and condyles in patients receiving either maxillary advancement and mandibular setback or maxillary surgery only.

METHODS

High-resolution cone-beam computed tomography scans were taken of 21 patients before and after orthognathic surgery. Ten patients with various malocclusions underwent maxillary surgery only, and 11 Class III patients received maxillary advancement and mandibular setback. Presurgery and postsurgery 3D models were registered on the surface of the cranial base. A new tool was used for graphical overlay and 3D display with color maps to visually assess the locations and to quantify positional changes in the posterior border of the mandibular rami and condyles between superimposed models.

RESULTS

The average displacements in condylar position were small--0.77 mm (SD, 0.12 mm) and 0.70 mm (SD, 0.08 mm)--for 2-jaw and 1-jaw surgeries, respectively (not significant, P >.05). All 2-jaw surgery patients had backward rotational displacements of the mandibular rami (mean, 1.98 mm; SD, 1.03 mm), with a maximum surface distance change of > or =2 mm in 8 of 11 subjects. For the 1-jaw surgery, all subjects had small backward rotational displacements of the mandibular rami (mean, 0.78 mm; SD, 0.25 mm), with only 1 subject having a maximum surface distance change > or =2 mm. The difference in mean backward rotational displacement was statistically significant (P <.01).

CONCLUSIONS

The visualization of 3D model superimposition clearly identified the location, magnitude, and direction of mandibular displacement. The 3D imaging allowed quantification of vertical, transverse, and anteroposterior ramus displacement that accompanied mandibular, but not maxillary only, surgery.