Artificial intelligence as a prediction tool for orthognathic surgery assessment.

INTRODUCTION: An ideal orthodontic treatment involves qualitative and quantitative measurements of dental and skeletal components to evaluate patients' discrepancies, such as facial, occlusal, and functional characteristics. Deciding between orthodontics and orthognathic surgery remains challenging, especially in borderline patients. Advances in technology are aiding clinical decisions in orthodontics. The increasing availability of data and the era of big data enable the use of artificial intelligence to guide clinicians' diagnoses. This study aims to test the capacity of different machine learning (ML) models to predict whether orthognathic surgery or orthodontics treatment is required, using soft and hard tissue cephalometric values. METHODS: A total of 920 lateral radiographs from patients previously treated with either conventional orthodontics or in combination with orthognathic surgery were used, comprising n = 558 Class II and n = 362 Class III patients, respectively. Thirty-two measures were obtained from each cephalogram at the initial appointment. The subjects were randomly divided into training (n = 552), validation (n = 183), and test (n = 185) datasets, both as an entire sample and divided into Class II and Class III sub-groups. The extracted data were evaluated using 10 machine learning models and by a four-expert panel consisting of orthodontists (n = 2) and surgeons (n = 2). RESULTS: The combined prediction of 10 models showed top-ranked performance in the testing dataset for accuracy, F1-score, and AUC (entire sample: 0.707, 0.706, 0.791; Class II: 0.759, 0.758, 0.824; Class III: 0.822, 0.807, 0.89). CONCLUSIONS: The proposed combined 10 ML approach model accurately predicted the need for orthognathic surgery, showing better performance in Class III patients.

Is three-piece maxillary segmentation surgery a stable procedure?

Objective: : The number of three-piece maxillary osteotomies has increased over the years; however, the literature remains controversial. The objective of this study was to evaluate the skeletal stability of this surgical modality compared with that of one-piece maxillary osteotomy. Methods: : This retrospective cohort study included 39 individuals who underwent Le Fort I maxillary osteotomies and were divided into two groups: group 1 (three pieces, n = 22) and group 2 (one piece, n = 17). Three cone-beam computed tomography scans from each patient (T1, pre-surgical; T2, post-surgical; and T3, follow-up) were used to evaluate the three-dimensional skeletal changes. Results: : The differences within groups were statistically significant only for group 1 in terms of surgical changes (T2-T1) with a mean difference in the canine region of 3.09 mm and the posterior region of 3.08 mm. No significant differences in surgical stability were identified between or within the groups. The mean values of the differences between groups were 0.05 mm (posterior region) and -0.39 mm (canine region). Conclusions: : Our findings suggest that one- and three-piece maxillary osteotomies result in similar post-surgical skeletal stability.

Enhancing skeletal stability and Class III correction through active orthodontist engagement in virtual surgical planning: A voxel-based 3-dimensional analysis.

INTRODUCTION: Skeletal stability after bimaxillary surgical correction of Class III malocclusion was investigated through a qualitative and quantitative analysis of the maxilla and the distal and proximal mandibular segments using a 3-dimensional voxel-based superimposition among virtual surgical predictions performed by the orthodontist in close communication with the maxillofacial surgeon and 12-18 months postoperative outcomes. METHODS: A comprehensive secondary data analysis was conducted on deidentified preoperative (1 month before surgery [T1]) and 12-18 months postoperative (midterm [T2]) cone-beam computed tomography scans, along with virtual surgical planning (VSP) data obtained by Dolphin Imaging software. The sample for the study consisted of 17 patients (mean age, 24.8 ± 3.5 years). Using 3D Slicer software, automated tools based on deep-learning approaches were used for cone-beam computed tomography orientation, registration, bone segmentation, and landmark identification. Colormaps were generated for qualitative analysis, whereas linear and angular differences between the planned (T1-VSP) and observed (T1-T2) outcomes were calculated for quantitative assessments. Statistical analysis was conducted with a significance level of α = 0.05. RESULTS: The midterm surgical outcomes revealed a slight but significantly less maxillary advancement compared with the planned position (mean difference, 1.84 ± 1.50 mm; P = 0.004). The repositioning of the mandibular distal segment was stable, with insignificant differences in linear (T1-VSP, 1.01 ± 3.66 mm; T1-T2, 0.32 ± 4.17 mm) and angular (T1-VSP, 1.53° ± 1.60°; T1-T2, 1.54° ± 1.50°) displacements (P >0.05). The proximal segments exhibited lateral displacement within 1.5° for both the mandibular right and left ramus at T1-VSP and T1-T2 (P >0.05). CONCLUSIONS: The analysis of fully digital planned and surgically repositioned maxilla and mandible revealed excellent precision. In the midterm surgical outcomes of maxillary advancement, a minor deviation from the planned anterior movement was observed.

Effectiveness of disk repositioning and suturing comparing open-joint versus arthroscopic techniques: a systematic review and meta-analysis.

OBJECTIVE: The aim of this study was to present a systematic review of the effectiveness of discopexy in managing internal derangement of the temporomandibular joint (TMJ). STUDY DESIGN: We searched MEDLINE through PubMed, SCOPUS, Web of Science, and Cochrane Central Register of Controlled Trials and grey literature accessed through Google Scholar, Openthesis, and hand-searching from inception to July 2020. The search strategy yielded 363 potentially relevant studies. After screening titles and abstracts, 41 full-text articles were assessed for eligibility and 7 studies were included in the meta-analysis. RESULTS: There was an overall decrease in visual analog scale (VAS) pain score of 4.59 cm (95% confidence interval [CI], 2.03-7.16; P < .001) during the follow-up time and an overall increase of 10 mm (95% CI, 6.93-13.01; P < .001) in mouth opening after TMJ surgeries with discopexy. CONCLUSIONS: The available evidence showed an overall decrease in VAS pain score and an improvement in mouth opening after TMJ surgeries with discopexy. Changes in maximal interincisal opening were greater after arthroscopic disk repositioning compared to open-joint procedure.

Craniofacial and airway morphology of individuals with oculoauriculovertebral spectrum.

OBJECTIVES: The objectives of this study were to characterize the craniofacial and airway morphology of oculo-auriculo-vertebral spectrum (OAVS) individuals using computed tomography (CT) examination. SETTING AND SAMPLE POPULATION: This sample included individuals in the age range from 5 to 14 years, consisted of a group of 18 OAVS individuals (12 females and 6 males), Pruzansky-Kaban1 IIB and III and by a paired control group matched by age and sex for comparison of morphometric and airway variables. MATERIALS AND METHODS: Through the CT examination, airway analysis was performed using Dolphin Imaging® Software, and seven morphometric measurements were performed to evaluate craniofacial morphology by Materialize Mimics® Software. To compare airway and morphometric variables, the control group was used. Student's t test and Mann-Whitney U test were performed to compare differences between the groups. RESULTS: Statistically significant differences were showed between the control and OAVS groups for the variables: total airway (TA) area, volume and MAA, RP area, RP volume, RP MAA, RG volume, RG MAA, total posterior height diff, Md incl and y-axis asymmetry. Pearson and Spearman's correlation showed mostly moderate correlations between Mand Occlusal canting AS with TA area and RP volume, Ax-Gn with TA area and Hy-C3 with TA volume. CONCLUSIONS: The OAVS's airway was altered and worse than the control group. Our results suggest that the contralateral side of OAVS individuals is unaffected; however, longitudinal assessments are needed to confirm it. Hyoid bone and postural measures play an important role in interpreting airway features of individuals with and without OAVS.

Can palatal splint improve stability of segmental Le Fort I osteotomies?

OBJECTIVES: The purpose of this study was to evaluate the influence of a palatal splint on stability in multi-segment maxillary osteotomies. SETTING AND SAMPLE POPULATION: Retrospective series of fifty-one adult patients, consecutively operated with bilateral sagittal split osteotomy (BSSO) and three-piece maxillary osteotomies, divided according to the use of a palatal splint (Group 1, n = 30) or no palatal splint (Group 2, n = 21). MATERIALS AND METHODS: Maxillary surgical casts (T1) and post-retention casts (T2), taken at least six months after discontinuation of orthodontic retention, were digitized (MicroScribe-3DX), measured and compared. Fifty-one landmarks were identified on the maxillary, transverse dimension changes and arch length were calculated. Longitudinal changes in all measurements were assessed by t test. RESULTS: Post-surgical transverse instability in group 1 ranged from 0.3 ± 0.4 to -1.3 ± 0.2 mm and was statistically significantly smaller than in group 2 that ranged from -1.0 ± 0.3 to -2.5 ± 0.5 mm. CONCLUSIONS: The use of a palatal splint after segmental Le Fort I maxillary osteotomy improved transverse stability in the posterior region. The post-surgical transverse instability occurred only between canine gingival points and thus suggesting no clinical relevance.

Cone-beam computed tomography airway measurements: Can we trust them?

INTRODUCTION: Pharyngeal airway space (PAS) assessment has been used in the past for a better understanding of orthodontic and surgical outcomes; however, this analysis could be unreliable. Our objective was to evaluate possible changes in the PAS reading in the same patient from their consecutive cone-beam computed tomography (CBCT) scans. METHODS: We evaluated a total of 27 patients' CBCT scans obtained at 2 time points with the use of a standardized acquisition protocol. The mean age at T0 was 31 years (range 17-62 years) and the follow-up records (T1) were taken after 4-6 months. Dolphin Imaging software was used to measure the volumes of the nasopharynx, oropharynx, and hypopharynx. We also evaluated the craniocervical position with the use of a lateral cephalogram. RESULTS: The variables exhibited high intraclass correlation coefficients (ICCs) when measuring the same CBCT scan twice (T0 and T0). However, The ICC between the measurements performed on the first and second CBCT scans (T0 and T1) showed that the only variable with high reproducibility between the 2 scans was cranial base, with an ICC >0.97. Average differences of 682.1 mm3, 2255.3 mm3, and 517.4 mm3 were found for the nasopharynx, oropharynx, and hypopharynx, respectively. Regarding the cephalometric angles, average differences between T0 and T1 scans were 0.6°, 2.7°, and 0.4° for OPT.CVT, OPT.SN, and cranial base, respectively. CONCLUSIONS: Different CBCT exams with equal scanning and patient positioning protocols can result in different 3D PAS readings. A more careful interpretation of CBCT volumetric data to achieve adequate conclusions of the clinical outcomes is necessary.

Three-dimensional quantitative assessment of surgical stability and condylar displacement changes after counterclockwise maxillomandibular advancement surgery: Effect of simultaneous articular disc repositioning.

INTRODUCTION: In this study, we quantitatively assessed 3-dimensional condylar displacement during counterclockwise maxillomandibular advancement surgery (CMMA) with or without articular disc repositioning, focusing on surgical stability in the follow-up period. METHODS: The 79 patients treated with CMMA had cone-beam computed tomography scans taken before surgery, immediately after surgery, and, on average, 15 months postsurgery. We divided the 142 condyles into 3 groups: group 1 (n = 105), condyles of patients diagnosed with symptomatic presurgical temporomandibular joint articular disc displacement who had articular disc repositioning concomitantly with CMMA; group 2 (n = 23), condyles of patients with clinical verification of presurgical articular disc displacement who had only CMMA; and group 3 (n = 14), condyles of patients with healthy temporomandibular joints who had CMMA. Presurgical and postsurgical 3-dimensional models were superimposed using voxel-based registration on the cranial base. Three-dimensional cephalometrics and shape correspondence were applied to assess surgical and postsurgical displacement changes. RESULTS: Immediately after surgery, the condyles moved mostly backward and medially and experienced lateral yaw, medial roll, and upward pitch in the 3 groups. Condyles in group 1 showed downward displacement, whereas the condyles moved upward in groups 2 and 3 (P ≤0.001). Although condylar displacement changes occurred in the 3 groups, the overall surgical procedure appeared to be fairly stable, particularly for groups 1 and 3. Group 2 had the greatest amount of relapse (P ≤0.05). CONCLUSIONS: CMMA has been shown to be a stable procedure for patients with healthy temporomandibular joints and for those who had simultaneous articular disc repositioning surgery.

Three-dimensional stability analysis of maxillomandibular advancement surgery with and without articular disc repositioning.

This retrospective cohort study aimed to assess, three-dimensionally, mandible and maxilla changes following maxillomandibular advancement (MMA), with and without repositioning of TMJ articular discs. The sample comprised cone-beam computed tomography data from 32 subjects: group 1 (n = 12) without disc displacement and group 2 (n = 20) with bilateral disc repositioning. An automatic cranial base superimposition method was used to register the images at three time points: T1 (preoperative), T2 (postoperative), and T3 (at least 11 months follow-up). To assess surgical changes (T2-T1) and adaptive responses (T3-T2), the images were compared quantitatively and qualitatively using the shape correspondence method. The results showed that surgical displacements were similar in both groups for all the regions of interest except the condyles, which moved in opposite directions - group 1 to superior and posterior positions, and group 2 to inferior and anterior positions. For adaptive responses, we observed high individual variability, with lower variability in group 2. Sagittal relapse was similar in both groups. In conclusion, there were no significant differences in skeletal stability between the two groups. The maxillomandibular advancement surgeries, with rotation of the occlusal plane, had stable results for both groups immediately after surgery and at 1-year follow-up.

Effect of temporomandibular joint articular disc repositioning on anterior open-bite malocclusion: An orthodontic-surgical approach.

An anterior open bite is a challenge to orthodontic treatment; it has a multifactorial etiology and a wide range of intervention options. Temporomandibular joint (TMJ) disorders are a risk factor for the development of malocclusions such as the anterior open bite, especially in patients who have TMJ osteoarthritis with disc displacement. Articular disc repositioning surgery is an available option for treating this pathology, and it contributes to maintaining the condyles in a more stable position. The aim of this article was to report the case of a 20-year-old woman diagnosed with anterior open bite and TMJ osteoarthritis with bilateral disc displacement. The patient received both orthodontic treatment and TMJ disc repositioning surgery. Cone-beam computed tomography was used to create 3-dimensional models of the condyles with regional superposition, and assessment of bone remodeling was performed at different time intervals. Complete orthodontic and surgical treatment time was approximately 12 months. The results provided a stable correction of the patient's anterior open bite with a 2-year follow-up and favorable bone remodeling of the condyles due to functional improvement of the TMJ.

Accuracy of biomarkers obtained from cone beam computed tomography in assessing the internal trabecular structure of the mandibular condyle.

OBJECTIVE: The aim of this study was to validate the ability of cone beam computed tomography (CBCT) to measure condylar internal trabecular bone structure and bone texture parameters accurately. STUDY DESIGN: Sixteen resected condyles of individuals undergoing temporomandibular joint replacement were collected and used as samples. These condyles were then radiographically imaged by using clinically oriented dental CBCT and research oriented micro-computed tomography (micro-CT). The CBCT scans were then compared with the gold standard micro-CT scans in terms of 21 bone imaging parameters. Descriptive histologic investigation of the specimens was also performed. RESULTS: Significant correlations were found for several imaging parameters between the CBCT and micro-CT images, including trabecular thickness (r = 0.92), trabecular separation (r = 0.78), bone volume (r = 0.90), bone surface area (r = 0.79), and degree of anisotropy measurements (r = 0.77). CONCLUSIONS: Measurements of trabecular thickness, trabecular separation, bone volume, bone surface area, and degree of anisotropy obtained from high-resolution dental CBCT images may be suitable bone imaging biomarkers that can be utilized clinically and in future research.

From ideal occlusion to dentofacial deformity and back to ideal: an osteochondroma treatment with lingual orthodontics.

This original case report describes the morphologic changes caused by a mandibular condylar osteochondroma (OC) on a female patient and its treatment. The changes were identified by comparing her final records from a previous orthodontic treatment, without the presence of OC, to records taken before a second treatment, with a developed OC. The diagnostics and treatment for the OC and its consequences were described and discussed in this paper. Treatment included orthodontics with a lingual appliance, low condylectomy on the affected side, high condylectomy on the contralateral side, bilateral disc repositioning and orthognathic surgery. It was concluded that the OC caused a Class III subdivision malocclusion, midline deviation and an edge-to-edge bite on the left side, a cant of the occlusal plane on the Z-axis and a deviation of the pogonion to the left. Treatment was successful and stable long term (36 months) with good occlusal, aesthetical and functional results.

Cone beam computed tomography-based models versus multislice spiral computed tomography-based models for assessing condylar morphology.

OBJECTIVE: To quantitatively compare condylar morphology using cone beam computed tomography (CBCT) and multislice spiral computed tomography (MSCT) virtual three-dimensional surface models. STUDY DESIGN: The sample consisted of secondary data analyses of CBCT and MSCT scans obtained for clinical purposes from 74 patients treated with condylar resection and prosthetic joint replacement. Three-dimensional surface models of 146 condyles were constructed from each scan modality. Across-subject models were approximated and voxel-based registration was performed between homologous CBCT and MSCT images, making it possible to create average CBCT- and MSCT-based condylar models. SPHARM-PDM software provided matching points on each corresponding model. ShapeAnalysisMANCOVA software assessed statistically significant differences between observers and imaging modalities. One-sample t-tests evaluated the null hypothesis that the mean differences between each CBCT- and MSCT-based model were not clinically significant (<.5 mm). Tests were conducted at a significance level of P < .05. RESULTS: ShapeAnalysisMANCOVA showed no statistically significant difference between the average CBCT- and MSCT-based models (P > .68). During pairwise comparison, the mean difference observed was .406 mm (SD, .173). One sample t-test showed that mean differences between each set of paired CBCT- and MSCT-based models were not clinically significant (P = .411). CONCLUSION: Three-dimensional surface models constructed from CBCT images are comparable to those derived from MSCT scans and may be considered reliable tools for assessing condylar morphology.

Maxillary molar intrusion with zygomatic anchorage in open bite treatment: lateral and oblique cephalometric evaluation.

PURPOSE: We aimed to use lateral and oblique radiographs to evaluate dental and skeletal changes arising from maxillary molar intrusion with zygomatic anchorage in open bite patients. METHODS: We conducted a pilot study including nine patients (six females and three males; mean age, 18.7 ± 5.1 years) with skeletal open bite treated with titanium miniplates for posterior dentoalveolar intrusion. Lateral and oblique (right and left, 45°) radiographs were obtained before (T1) and 6 months after intrusion (T2). A paired t test was used for statistical evaluation. RESULTS: The maxillary posterior teeth were intruded 2.03 ± 0.87 mm (p < 0.01) with 450×g of force, which resulted in counterclockwise rotation of the mandible (1.57°, p = 0.02) and clockwise rotation of the occlusal plane (4.27 ± 2.66°, p = 0.01). Anterior facial height decreased by a mean of 1.79 ± 1.51 mm (p < 0.01). No significant change in the palatal plane or in anteroposterior molar movement was observed. CONCLUSION: The oblique radiograph at 45° was useful for the assessment of molar intrusion and anteroposterior displacement. The treatment of anterior open bite with skeletal anchorage provided intrusion of molars and counterclockwise rotation of the mandible, resulting in open bite closure.

Condylar resorption of the temporomandibular joint: how do we treat it?

Condylar resorption (CR) is a common sequela of some temporomandibular joint (TMJ) abnormalities. CR can result in jaw deformities and dysfunction, malocclusion, pain, headaches, and airway obstruction. Most cases can be classified into 1 of 4 categories based on cause: (1) adolescent internal CR; (2) reactive (inflammatory) arthritis; (3) autoimmune and connective tissue diseases; and (4) other end-stage TMJ pathologic abnormality. MRI is helpful in differentiating the cause and defining treatment options. This article presents the nature and progression of the different TMJ CR pathologic abnormalities, clinical and imaging characteristics, and treatment options to produce predictable and stable outcomes.

Disc repositioning: does it really work?

Although limited, there is evidence to support the assumption that temporomandibular joint (TMJ) articular disc repositioning indeed works; to date, there is no evidence that TMJ articular disc repositioning does not work. Despite the controversy among professionals in private practice and academia, TMJ articular disc repositioning is a procedure based on (still limited) evidence; the opposition is based solely on clinical preference and influenced by the ability to perform it or not.

Photographic assessment of hyperdivergent skeletal Class II patients / Avaliação fotográfica de pacientes padrão esquelético classe II hiperdivergentes

Desordens temporomandibulares, distúrbios do sono por obstrução das vias aéreas e alterações na postura crânio cervical constituem alguns dos problemas que têm sido relacionados com o paciente padrão esquelético classe II hiperdivergente. Embora as telerradiografias laterais representem o padrão ouro para o diagnóstico da morfologia cranio facial na prática clínica, este exame pode não ser viável para aplicação em estudos epidemiológicos de larga escala. Objetivo: O objetivo deste estudo foi testar a validade de um novo método fotográfico no diagnóstico de pacientes classe II hiperdivergentes para fins de investigação epidemiológica. Material e Métodos: Telerradiografias laterais e fotografias de perfil foram obtidas a partir de 123 indivíduos distribuídos em dois grupos: 51 pacientes compuseram o grupo de pacientes classe II hiperdivergente, enquanto que os outros 72 pacientes formaram um segundo grupo. A análise discriminante descreveu um modelo matemático para melhor diagnosticar pacientes padrão esquelético classe II hiperdivergente através de fotografias. Resultados: Uma função canônica discriminante composta por duas variáveis fotográficas classificou corretamente 85% dos pacientes classe II hiperdivergentes durante a validação interna (p < 0,001). O método mostrou 83% de sensibilidade e 73% de especificidade no processo de validação externa. Conclusão: O método fotográfico pode ser considerado como uma alternativa viável e prática para diagnosticar o paciente classe II hiperdivergente, particularmente se existir a necessidade de um método não invasivo e de baixo custo.

Temporomandibular disorders, sleep disturbances by airway obstruction and craniocervical posture changes constitute some of the problems that have been related to hyperdivergent skeletal Class II patients. Although cephalometric radiographs represent the gold standard for diagnosing craniofacial morphology in clinical practice, it might not be feasible for large-scale epidemiological research. Objectives: The aim of this study was to test the validity of a new photographic method in diagnosing hyperdivergent skeletal Class II patients for epidemiological research purposes. Material and Methods: Lateral cephalograms and profile photographs were obtained from 123 subjects assigned into two groups. 51 patients comprised the hyperdivergent skeletal Class II group and the other 72 composed a second group. Discriminant analysis described a mathematical model to better diagnose hyperdivergent skeletal Class II patients through photographs. Results: A canonical discriminant function composed of two photographic variables correctly classified 85% of the hyperdivergent skeletal Class II patients during internal validation (p < 0.001). The method showed 83% sensitivity and 73% specificity in external validation procedure. Conclusion: The photographic method may be a feasible and practical alternative for diagnosing the hyperdivergent skeletal Class II patient, particularly if there is a need for a low-cost and noninvasive method.

Can cone-beam computed tomography superimposition help orthodontists better understand relapse in surgical patients?

This case report describes the interdisciplinary treatment of a 19-year-old Brazilian man with a Class I malocclusion, a hyperdivergent profile, an anterior open bite, and signs of temporomandibular joint internal derangement. The treatment plan included evaluation with a temporomandibular joint specialist and a rheumatologist, orthodontic appliances, and maxillomandibular surgical advancement with counterclockwise rotation. Cone-beam computed tomography images were taken before and after surgery at different times and superimposed at the cranial base to assess the changes after orthognathic surgery and to monitor quantitatively the internal derangement of the temporomandibular joints and surgical relapse. Our protocol can improve the orthodontist's understanding of surgical instability, demonstrate the clinical value of cone-beam computed tomography analysis beyond the multiplanar reconstruction, and guide patient management for the best outcome possible.

Three-dimensional dental arch changes of patients submitted to orthodontic-surgical treatment for correction of Class II malocclusion.

INTRODUCTION: This study assessed the three-dimensional changes in the dental arch of patients submitted to orthodontic-surgical treatment for correction of Class II malocclusions at three different periods. METHODS: Landmarks previously identified on upper and lower dental casts were digitized on a three-dimensional digitizer MicroScribe-3DX and stored in Excel worksheets in order to assess the width, length and depth of patient's dental arches. RESULTS: During orthodontic preparation, the maxillary and mandibular transverse dimensions measured at the premolar regions were increased and maintained throughout the follow-up period. Intercanine width was increased only in the upper arch during orthodontic preparation. Maxillary arch length was reduced during orthodontic finalization, only. Upper and lower arch depths were stable in the study periods. Differences between changes in centroid and gingival points suggested that upper and lower premolars buccaly proclined during the pre-surgical period. CONCLUSIONS: Maxillary and mandibular dental arches presented transverse expansion at premolar regions during preoperative orthodontic preparation, with a tendency towards buccal tipping. The transverse dimensions were not altered after surgery. No sagittal or vertical changes were observed during the follow-up periods.

Three-dimensional dental arch changes of patients submitted to orthodontic-surgical treatment for correction of Class II malocclusion

INTRODUCTION: This study assessed the three-dimensional changes in the dental arch of patients submitted to orthodontic-surgical treatment for correction of Class II malocclusions at three different periods. METHODS: Landmarks previously identified on upper and lower dental casts were digitized on a three-dimensional digitizer MicroScribe-3DX and stored in Excel worksheets in order to assess the width, length and depth of patient's dental arches. RESULTS: During orthodontic preparation, the maxillary and mandibular transverse dimensions measured at the premolar regions were increased and maintained throughout the follow-up period. Intercanine width was increased only in the upper arch during orthodontic preparation. Maxillary arch length was reduced during orthodontic finalization, only. Upper and lower arch depths were stable in the study periods. Differences between centroid and gingival changes suggested that upper and lower arch premolars buccaly proclined during the pre-surgical period. CONCLUSIONS: Maxillary and mandibular dental arches presented transverse expansion at premolar regions during preoperative orthodontic preparation, with a tendency towards buccal tipping. The transverse dimensions were not altered after surgery. No sagittal or vertical changes were observed during the follow-up periods. .

INTRODUÇÃO: esse estudo avaliou as alterações tridimensionais ocorridas na morfologia das arcadas dentárias de pacientes submetidos ao tratamento ortodôntico-cirúrgico para a correção da má oclusão de Classe II, em três períodos distintos: (T1) modelos iniciais, (T2) modelos pré-cirúrgicos imediatos (de 1 a 15 dias antes da cirurgia) e (T3) modelos pós-cirúrgicos (mínimo de 6 meses após a remoção do aparelho ortodôntico). MÉTODOS: pontos previamente demarcados em cada modelo foram digitalizados por meio do digitalizador tridimensional MicroScribe-3DX, cujas coordenadas, armazenadas em planilhas do programa Excel, deram origem a valores que possibilitaram a avaliação da largura, comprimento e profundidade das arcadas dentárias. RESULTADOS: durante o preparo ortodôntico, houve aumentos nas distâncias transversais superiores e inferiores medidas na região de pré-molares que se mantiveram no período total de acompanhamento. Apenas a distância intercaninos superior apresentou alterações de aumento durante o preparo ortodôntico, assim como a largura da arcada superior, que diminuiu durante a fase de finalização. A profundidade de ambas as arcadas manteve-se estável nas fases avaliadas. Diferenças entre as mudanças dos pontos centroide e gengival sugerem que os pré-molares superiores e inferiores inclinaram para vestibular durante o preparo ortodôntico pré-cirúrgico. CONCLUSÇÕES: conclui-se que as arcadas dentárias superiores e inferiores sofreram expansão transversal na região de pré-molares durante o preparo ortodôntico pré-cirúrgico, com tendência à inclinação vestibular de todos os dentes posteriores. Após a cirurgia, as dimensões transversais ...