Skeletal, dentoalveolar and soft tissue changes after stabilization splint treatment for patients with temporomandibular joint disorders.

BACKGROUND: Temporomandibular disorder (TMD) is a grouping of heterogeneous disorders with multifactorial origins. Stabilization splints (SS) have demonstrated an acceptable treatment effect in TMD. The possible changes at the skeletal, dental, and soft tissue levels need to be addressed to evaluate the benefit/risk ratio of this therapeutic procedure. Accordingly, this study aimed to three­dimensionally evaluate skeletal, dentoalveolar and soft tissue changes after SS treatment for patients with TMD. METHODS: This retrospective study included 74 adult patients with myofascial and/or intra-articular disorders (25 males and 49 females), with an average age of 22.88 ± 4.8 years, who underwent SS treatment. Pre- and post-treatment Cone beam computed tomography were analysed using Invivo 6.0.3 software. The primary outcome was the vertical skeletal and dentoalveolar changes, while the secondary outcomes were the anteroposterior skeletal, dentoalveolar and soft tissue changes. Paired t-test and Wilcoxon rank sum test were used for statistical analyses. RESULTS: For the primary outcome; skeletally, there was a significant increase in mandibular plane inclination (difference: 0.82°±1.37), decrease facial height ratio (difference: 0.45%±1.07) and at the dentoalveolar level, the inclination of the functional (FOP-SN, FOP-FH) and bisecting (BOP-SN, BOP-FH) occlusal planes exhibited a significant increase too (difference: 0.38 ± 1.43°, 0.49 ± 1.62°, 0.44 ± 1.29° and 0.41 ± 1.17°, respectively) and also a decrease in the overbite (difference: -0.54 ± 0.83). For the secondary outcomes; there was a significant decrease in mandibular position (SNB) (difference: 1.60 ± 1.36°) and increase in the overjet (difference: 0.93 ± 1.04, p < 0.001) and a significant lower lip retrusion (difference: 0.33 ± 1.01 mm p < 0.01), was observed too. CONCLUSIONS: SS therapy resulted in significant vertical skeletal and dentoalveolar changes that were manifested mainly by facial height ratio, mandibular and occlusal plane changes, and to a lesser extent, significant anteroposterior skeletal, dentoalveolar, and soft tissue changes in the form of mandibular position, increased overjet and a more retrusive lower lip. These changes should be considered during patients' selection prior to initiating SS therapy.

Alveolar bone changes following bi-maxillary vertical molars' movements using clear aligners.

OBJECTIVE: This study aimed to assess the alveolar bone changes following maxillary and mandibular molars' intrusion and extrusion movements using Clear Aligners using Cone-Beam Computed Tomography (CBCT). MATERIALS AND METHODS: This is a retrospective clinical study in which 24 adult patients with pre-designed selection criteria and a mean age of 31.1 + 9.9 years were enrolled. The alveolar bone changes around one hundred thirty-three maxillary and mandibular molars intruded or extruded by Clear Aligners therapy were analyzed from CBCT using Invivo 6.0 software. Intra- and inter-examiner reliability analysis was performed using the intra-class correlation coefficient (ICC) and Cronbach's Alpha statistics. The paired t-test was used to analyze significant differences before and after treatment (T0-T1). The significance level was considered at P < 0.05. RESULT: The patients were divided into two groups: extrusion (48.9%, n = 65 molars' root) and intrusion (51.1%, n = 68 molars' root) group. There was a significant decrease in the alveolar bone changes in the buccal surface of the mandibular right and left 1st molars in the extrusion group (-1.05 ± 0.97, -0.76 ± 1.12 mm, respectively) and the maxillary left 2nd molars in intrusion group (-0.42 ± 0.77 mm), and the lingual surface of intrusion of the mandibular left 1st molar (-0.64 ± 0.76 mm). Comparing the mean maxillary and mandibular changes (T0-T1) of both studied groups showed that the buccal alveolar bone changes for the left 1st and right 2nd molars showed a significant difference in extrusion and intrusion groups, respectively. CONCLUSIONS: The buccal alveolar bone changes is considered the most affected surface following maxillary and mandibular molars' intrusion and extrusion movements using clear aligners, with mandibular molars being more affected than the maxillary ones.

Three-dimensional phenotype characteristics of skeletal class III malocclusion in adult Chinese: a principal component analysis-based cluster analysis.

BACKGROUND: Skeletal class III malocclusion has a diverse and complicated aetiology involving environmental and genetic factors. It is critical to correctly classify and define this malocclusion to be diagnosed and treated on a clinically sound basis. Thus, this study aimed to provide reliable and detailed measurements in a large ethnically homogeneous sample of Chinese adults to generate an adequate phenotypic clustering model to identify and describe the skeletal variation present in skeletal class III malocclusion. MATERIALS AND METHODS: This is a retrospective cross-sectional study in which 500 pre-treatments cone-beam computed tomography (CBCT) scans of patients with skeletal class III malocclusion (250 males and 250 females) were selected following specific selection criteria. Seventy-six linear, angular, and ratios measurements were three-dimensionally analysed using InVivo 6.0.3 software. These measurements were categorised into 47 skeletal, 18 dentoalveolar, and 11 soft tissue variables. Multivariate reduction methods: principal component analyses and cluster analyses were used to present the most common phenotypic groupings of skeletal class III malocclusion in Han ethnic group of Chinese adults. RESULTS: The principal component analysis revealed eight principal components accounted for 72.9% of the overall variation of the data produced from the seventy-six variables. The first four principal components accounted for 53.37% of the total variations. They explained the most variation in data and consisted mainly of anteroposterior and vertical skeletal relationships. The cluster analysis identified four phenotypes of skeletal class III malocclusion: C1, 34%; C2, 11.4%; C3, 26.4%; and C4, 28.2%. CONCLUSION: Based on three-dimensional analyses, four skeletal class III malocclusion distinct phenotypic variations were defined in a large sample of the adult Chinese population, showing the occurrence of phenotypic variation between identified clusters in the same ethnic group. These findings might serve as a foundation for accurate diagnosis and treatment planning of each cluster and future genetic studies to determine the causative gene(s) of each cluster.

Three-dimensional assessment of the favorability of maxillary posterior teeth intrusion in different skeletal classes limited by the vertical relationship with the maxillary sinus floor.

BACKGROUND: Understanding the anatomical relationship between the maxillary sinus floor (MSF) and the posterior maxillary teeth (PMT) is important when planning the orthodontic intrusion of the posterior teeth. This study aimed to determine the vertical relationship between posterior maxillary teeth and maxillary sinus floor in different skeletal classes in the Chinese adult population. METHODS: This is a retrospective cross-sectional study involved cone beam computed tomography images of 298 adult patients (145 males and 153 females) between 20 and 45 years old. The sample was categorized according to A point, Nasion, B point (ANB) angle into 102 Class I, 102 Class II, and 94 Class III malocclusion. Non-parametric Wilcoxon Mann-Whitney U and Kruskal-Wallis tests were used to compare the studied groups. The Intra-class Correlation Coefficient (ICC) was used to assess the intra- and inter-observer reliability analysis. RESULTS: Overall, there was a statistically significant difference in the mean distance between both genders (P < 0.001). The measured distance increased with age in all posterior tooth roots (P < 0.001). The root apex in the sagittal view appeared to be closer to the maxillary sinus than in the coronal view; 2.2 ± 4.3 and 3.1 ± 5.5 mm, respectively. The most frequent root scores were Type 1 and Type 2P. In both sagittal and coronal views, Class I demonstrated a higher Type 2P prevalence, whereas Class III showed a lower prevalence. The second molars' mesiobuccal root had the largest number of penetration in the three examined skeletal classes. CONCLUSIONS: Maxillary molars of Class I malocclusion with the majority of Type 2P root-sinus relationship have the highest possible risk of root resorption during molar intrusion due to cortical bone encroachment, while Class III malocclusion showed the least possible risk.

Three-dimensional assessment of the favorability of maxillary posterior teeth intrusion in different facial patterns limited by the vertical relationship with the maxillary sinus floor.

OBJECTIVE: Posterior teeth intrusion is one of the best treatment options for treatment of skeletal open bite in adults; the surrounding anatomical landmarks are one of the restraining factors. This study aimed to assess the vertical relationship between the maxillary posterior teeth (MPT) and the maxillary sinus floor (MSF) in different facial growth patterns in the Chinese adult population. MATERIALS AND METHODS: Cone beam computed tomography images of 298 patients, 145 males and 153 females aged between 20 and 45 years, were analyzed. Based on Jarabak ratio and the mandibular plane inclination, the sample was categorized into 94 hyperdivergent, 102 hypodivergent, and 102 normodivergent facial patterns subjects. The vertical relationship between the root-apex distances were classified as favorable, indicating no contact (type 1), or unfavorable, indicating roots in contact (type 2) for the posterior teeth intrusion. The relationship in the unfavorable group was subdivided into three subgroups (T2C, T2LC, and T2P). Comparative statistical tests were done related to age, gender, tooth side, and type of multiplanar view (sagittal and coronal). The significant level was set to be P < 0.05. RESULTS: There was a statistically significant difference in the mean distance between both genders in the hyperdivergent group (P < 0.001). The measured distance increased with age in all tooth roots (P < 0.001). In both sagittal and coronal views, the most frequent root scores were type 1 and type 2p (54.2%, 27.5%) and (55.1%, 21.4%), respectively. The hyperdivergent group demonstrated a higher prevalence of type 2P (31.6% and 25.5%), whereas the hypodivergent group showed a lower prevalence (25.1% and 19.2%); furthermore, the second molar's mesiobuccal root in hyperdivergent patients showed the closest distance to the maxillary sinus in sagittal and coronal views, 0.3 ± 3.7 and 0.4 ± 3.1 mm, respectively. CONCLUSIONS: Maxillary molars of hyperdivergent patients have the highest possible risk of root resorption due to the possible risk of cortical bone encroachment, while hypodivergent patients have the least possible risk. CLINICAL RELEVANCE: Analysis of apex-sinus distances can be of great help for safe posterior teeth intrusion and providing correct and adequate treatment.

Three-dimensional assessment of temporomandibular joint in skeletal Class I malocclusion with variable degrees of overbite and overjet.

OBJECTIVE: To three-dimensionally evaluate the position and morphology of the TMJ in skeletal Class I with variable degrees of overbite and overjet in comparison with normal peers. METHODS: Pretreatment CBCT scans of 126 adults were retrieved. Based on the severity of overjet and overbite, the sample was divided into three main groups and six subgroups (18 patients each): the first group with a normal overbite and variable overjet degree and the second group with normal overjet and variable overbite degree. These six subgroups were compared with a third control group of normal overjet and overbite. RESULTS: There were significant differences in vertical condylar position, vertical and anteroposterior condylar inclinations, condylar height, and significant posterior condylar positioning in severe deep overbite, compared with the control group. CONCLUSION: There were significant changes in the TMJ components in severe deep overbite cases. Therefore, sever deep overbite could be considered a predisposing factor for temporomandibular disorders.

Proximity of upper central incisors to incisive canal among subjects with maxillary dentoalveolar protrusion in various facial growth patterns.

OBJECTIVE: To investigate the position of the upper central incisor roots (U1) relative to the incisive canal (IC) among subjects with maxillary dentoalveolar protrusion in various facial growth patterns. MATERIALS AND METHODS: 240 cone beam computed tomography images of skeletal Class I and II maxillary or bimaxillary protrusive subjects with a mean age of 23.74 ± 3.73 years were enrolled according to their facial growth pattern. The IC volume was measured using Mimics 21 software (Materialise, Leuven, Belgium). The U1 inter-root distance, width of IC, and their proximity were estimated using Invivo6 software (Anatomage, San Jose, CA). RESULTS: The IC volume was slightly greater among the high angle facial group and female patients than the other groups. Overall, the IC width was greater than the U1 inter-root distance in 55.65%, 57.6%, and 65% among the average, low, and high angle facial groups, respectively, and in 56.5% and 62.9% of males and females, respectively. The overall anteroposterior (sagittal) distances between the U1 roots and IC were 4.36 ± 1.18, 4.78 ± 1.17, and 3.83 ± 0.90 mm among the average, low, and high angle facial groups, respectively. CONCLUSIONS: The high angle facial group and female patients showed slightly greater IC dimensions than the other groups. The overall maximum sagittal distances between the U1 and IC were around 5.5, 6, and 4.7 mm among the average, low, and high angle facial groups, respectively. The low angle facial group and male patients tended to have greater sagittal distances. Therefore, the present findings could serve as a guideline when a considerable amount of upper incisor retraction is planned for Class I or II maxillary or bimaxillary dentoalveolar protrusion patients.

Three-dimensional assessment of asymmetric mid-palatal suture expansion assisted by a customized microimplant-supported rapid palatal expander in non-growing patients: Uncontrolled Clinical Trial.

OBJECTIVES: The objective was to evaluate the magnitude, incidence and possible factors of asymmetric expansion with a customized microimplant-supported rapid palatal expander (MARPE) in non-growing patients. SETTING AND SAMPLE POPULATION: This retrospective study included a sample of 49 patients (mean age: 23.9 ± 3.9 years) treated with a customized microimplant-supported rapid palatal expander. Based on the symmetry of expansion, the sample was divided into Group S (symmetric expansion group, n = 26) and Group A (asymmetric expansion group, n = 23). METHODS: Pre- and post-treatment cone-beam computed tomography (CBCT) images were superimposed to assess skeletal change in both studied groups. Seven variables were tested: unilateral crossbite, maxillary base cant, chin deviation, the initial asymmetrical position of the mid-palatal suture, split pattern of frontomaxillary suture, Angle's classification and dental arch crowding. Paired t-test and logistic regression analyses were utilized to evaluate the possible factors behind the asymmetric expansion. RESULTS: There was a significant difference (P < .01) between the studied groups. The average expansion was 4.26 mm at the anterolateral maxillary walls (BB) and 3.83 mm at the greater palatine foramen region (GPF). The average expansion at the GPF was 90% of that at the BB. The frequency of asymmetric expansion was 46.9%. Among the seven tested variables, the presence of the initial asymmetric position of the mid-palatal suture is the only variable that showed correlation with asymmetric expansion. CONCLUSION: Initial asymmetric position of the mid-palatal suture is considered a contributing factor of skeletal asymmetric expansion following microimplant-supported rapid palatal expansion in skeletally comparable patients.

Accuracy and reproducibility of permanent dentitions and dental arch measurements: comparing three different digital models with a plaster study cast.

AIM: The objective of the present study was to assess the accuracy and reproducibility of permanent dentition and dental arch measurements of three digital scanners compared with the gold standard, a physical plaster cast. MATERIALS AND METHODS: In this cross-sectional study, the following records of 30 patients were used: 1) orthodontic physical plaster study cast (PPSC); 2) digitally scanned physical model (DSPM), 3) direct intraoral model scanned with a Trios color scanner; and 4) direct 3D CBCT digital model. The following 3D measurements were obtained: mesiodistal tooth dimensions; total tooth materials; dental arch perimeters; total arch lengths; and intermolar, interpremolar, and intercanine widths. The measurements on the three digital models were contrasted with those on the PPSC. Differences were tested using a dependent t test for intragroup comparisons. A P value of < 0.05 was considered statistically significant. Intraclass correlation coefficient was used to assess intra- and interexaminer reliability. RESULTS: Except for the mesiodistal dimensions of the mandibular left central incisors (P < 0.001) and the mandibular intercanine width (P = 0.041), no statistically significant differences were found between the measurements made directly on the PPSC and those on the three digital models. The mean discrepancies between the methods ranged from as low as 0.003 mm to as high as 0.67 mm for the total tooth materials, and as low as 0.01 mm to as high as 0.37 mm for the total arch length. For the transverse dimension, the mean discrepancies ranged from as low as 0.3 mm for the maxillary intercanine width to as high as 0.5 mm for the mandibular intercanine width. However, these significant differences were not considered clinically significant. CONCLUSIONS: The DSPM, Trios color scanner digital model, and direct 3D CBCT digital model appear to be adequate, reliable, and time-saving alternatives to the PPSC when analyzed using a digital caliper.

Accuracy and Reproducibility of Facial Measurements of Digital Photographs and Wrapped Cone Beam Computed Tomography (CBCT) Photographs.

The study sought to assess whether the soft tissue facial profile measurements of direct Cone Beam Computed Tomography (CBCT) and wrapped CBCT images of non-standardized facial photographs are accurate compared to the standardized digital photographs. In this cross-sectional study, 60 patients with an age range of 18-30 years, who were indicated for CBCT, were enrolled. Two facial photographs were taken per patient: standardized and random (non-standardized). The non-standardized ones were wrapped with the CBCT images. The most used soft tissue facial profile landmarks/parameters (linear and angular) were measured on direct soft tissue three-dimensional (3D) images and on the photographs wrapped over the 3D-CBCT images, and then compared to the standardized photographs. The reliability analysis was performed using concordance correlation coefficients (CCC) and depicted graphically using Bland-Altman plots. Most of the linear and angular measurements showed high reliability (0.91 to 0.998). Nevertheless, four soft tissue measurements were unreliable; namely, posterior gonial angle (0.085 and 0.11 for wrapped and direct CBCT soft tissue, respectively), mandibular plane angle (0.006 and 0.0016 for wrapped and direct CBCT soft tissue, respectively), posterior facial height (0.63 and 0.62 for wrapped and direct CBCT soft tissue, respectively) and total soft tissue facial convexity (0.52 for both wrapped and direct CBCT soft tissue, respectively). The soft tissue facial profile measurements from either the direct 3D-CBCT images or the wrapped CBCT images of non-standardized frontal photographs were accurate, and can be used to analyze most of the soft tissue facial profile measurements.

Three-dimensional morphological and positional analysis of the temporomandibular joint in adults with posterior crossbite: A cross-sectional comparative study.

OBJECTIVES: The purpose of this study was to three-dimensionally (3D) evaluate the morphological and positional features of the temporomandibular joint (TMJ) in adults with unilateral and bilateral posterior crossbite compared with aligned control subjects. MATERIALS AND METHODS: This cross-sectional comparative study analysed cone beam computed tomography (CBCT) images of 90 adult subjects' divided into three equal groups: bilateral posterior crossbite (BCG), unilateral posterior crossbite (UCG) and control group (CG). 3D measurements of the TMJ included the following: (a) position, angulation and inclination of the mandibular condyles; (b) centralisation of the condyles in their respective mandibular fossae; and (c) volumetric measurements of the TMJ spaces. Intra- and intergroup differences were identified using the paired Student's t test and an analysis of variance (ANOVA) followed by Tukey's post hoc test, respectively. RESULTS: Regarding the intra-group side-based comparisons, there were significant differences in the anterior and superior joint spaces and the anteroposterior condylar joint position in the UCG. Intergroup comparisons revealed significant differences in the vertical condylar inclination, medial condylar position, condylar width and height, and volumetric joint space between the unaffected side of the UCG and left sides of the other groups. There were significant differences in the anteroposterior condylar inclination, medial condylar position, condylar width and height, anterior, posterior, superior and volumetric joint spaces, and anteroposterior condylar joint position between the crossbite side of the UCG and the right sides of the other groups. CONCLUSION: Skeletal crossbite accompanied with characteristic morphological and positional TMJ features associated with unilateral posterior crossbite and are associated with side-specific TMJ asymmetry.

Pharyngeal airway spaces in different skeletal malocclusions: a CBCT 3D assessment.

Objective: To three-dimensionally evaluate the upper pharyngeal airway spaces in adults with different anteroposterior and vertical skeletal malocclusions.Methods: In this retrospective study, three-dimensional airway volume and the minimum constricted areas of 120 adults were measured from cone beam computed tomography volume scans. The sample was divided into skeletal Class I and Class II and subdivided into average and long face malocclusions in each skeletal Class. Airway volumes of the naso-, palato-, and glossopharynx, and the minimum constricted area were measured and compared.Results: Skeletal Class II reduced glossopharyngeal airway volume and larger total minimum constricted area in average faces and more nasal minimum constricted area in long faces. Skeletal Class II with long face significantly increased palatopharyngeal and glossopharyngeal airway volumes as well as larger palatopharyngeal minimum constricted area (p < 0.05).Conclusion: This paper found a likely association between jaw skeletal classification and airway dimensions.

Three-dimensional assessment of accelerating orthodontic tooth movement-micro-osteoperforations vs piezocision: A randomized, parallel-group and split-mouth controlled clinical trial.

OBJECTIVE: To compare the effects of micro-osteoperforations (MOPs) vs piezocision (Piezo) in accelerating orthodontic tooth movement in adults. SETTING AND SAMPLE POPULATION: In this randomized, single-blinded, parallel-group, split-mouth clinical trial, 24 patients aged 15-40 years were recruited. SUBJECTS AND METHODS: Patients were randomly allocated into two groups: MOPs and Piezo groups. One side of the maxilla was allocated randomly for treatment with one of these techniques, and the other side was treated conventionally to act as a split-mouth control. The rate of canine retraction was evaluated up to 3 months by three-dimensional digital models using a conventional labial appliance. Root resorption and bone height were evaluated using cone beam computed tomography. RESULTS: The MOPs and Piezo groups showed a significantly higher rate of tooth movement after 3 months on the experimental sides than the control sides. However, the net movements in the MOPs and Piezo groups did not reveal a higher rate of tooth movement. Similarly, the overall net movement was -0.32 ± 1.14 and -0.55 ± 0.89 mm for MOPs and Piezo, respectively (P = .606). Regarding root resorption, the overall changes in intra- or intergroup comparisons were insignificant. Decreased canine palatal bone height was reported on the experimental side of the Piezo group (P = .015) after 3 months, but the overall changes were insignificant. CONCLUSIONS: The effect of MOPs and Piezo techniques in accelerating the orthodontic canine retraction was comparable to each other, and to the conventional methods. Neither technique caused root resorption or increased vertical bone loss.

Dentoalveolar compensation in different anterioposterior and vertical skeletal malocclusions.

BACKGROUND: To evaluate the position and inclination of maxillary and mandibular incisors in adults with different anteroposterior and vertical skeletal malocclusions. MATERIAL AND METHODS: In this retrospective study, lateral cephalometry of 272 adults (134 males and 138 females) who met the selection criteria were digitally analyzed. They were classified based on both linear and angular measurements, anterioposteriorly into skeletal Class I, Class II and Class III and vertically into hypodivergent, normodivergent and hyperdivergent individuals. Sixteen linear and angular measurements were used to assess both positions and inclinations of maxillary base, mandibular base, maxillary incisors, mandibular incisors, and inter-incisors relationship. Descriptive statistics were calculated and presented. The intra-class correlation coefficient (ICC) was applied for the reliability of measurements. Pearson correlation was used to present the degree of correlation between all variables. A P value of < 0.05 was considered significant. RESULTS: There was a significant correlation between anteroposterior skeletal discrepancy and maxillary and mandibular dentoalveolar compensation (P<0.001). There was significant correlation between vertical skeletal discrepancy and maxillary and mandibular dentoalveolar compensation except for maxillary incisor position. Anterioposterior skeletal jaw position had greater significant effect on the dentoalveolar changes than the vertical skeletal jaw inclination did with variant degree. CONCLUSIONS: There may be an association between dentoalveolar changes and the skeletal anteroposterior and vertical positions, inclinations and intermaxillary relation. Key words:Dentoalveolar compensation, anteroposterior, vertical, skeletal malocclusions, Cephalometry.

Three-dimensional skeletal and pharyngeal airway changes following therapy with functional appliances in growing skeletal Class II malocclusion patients : A controlled clinical trial.

INTRODUCTION: To three-dimensionally analyze the skeletal and pharyngeal airway changes induced by Twin Block (TWB) and Forsus Fatigue Resistance Device (FFRD) in skeletal Class II female patients compared with untreated controls. MATERIALS AND METHODS: The study comprised 62 growing female patients with skeletal Class II malocclusion due to mandibular retrusion treated with either TWB (n = 23) or FFRD (n = 21), or neither (n = 18; controls). Pre- and posttreatment/observational cone beam computed tomography images were used to evaluate the treatment changes. RESULTS: TWB induced more obvious mandibular skeletal changes and caused significant retrusive effects on the maxilla. Similarly, the sagittal and vertical jaw relationships were affected more obviously with TWB (P <0.001) compared to FFRD. Changes in oropharyngeal volume and minimal axial area were more obvious with TWB. DISCUSSION: The TWB functional appliance induced significant skeletal and pharyngeal airway changes. These changes were more obvious relative to the slight changes induced by FFRD or by natural growth.

Global distribution of malocclusion traits: A systematic review

Abstract Objective: Considering that the available studies on prevalence of malocclusions are local or national-based, this study aimed to pool data to determine the distribution of malocclusion traits worldwide in mixed and permanent dentitions. Methods: An electronic search was conducted using PubMed, Embase and Google Scholar search engines, to retrieve data on malocclusion prevalence for both mixed and permanent dentitions, up to December 2016. Results: Out of 2,977 retrieved studies, 53 were included. In permanent dentition, the global distributions of Class I, Class II, and Class III malocclusion were 74.7% [31 - 97%], 19.56% [2 - 63%] and 5.93% [1 - 20%], respectively. In mixed dentition, the distributions of these malocclusions were 73% [40 - 96%], 23% [2 - 58%] and 4% [0.7 - 13%]. Regarding vertical malocclusions, the observed deep overbite and open bite were 21.98% and 4.93%, respectively. Posterior crossbite affected 9.39% of the sample. Africans showed the highest prevalence of Class I and open bite in permanent dentition (89% and 8%, respectively), and in mixed dentition (93% and 10%, respectively), while Caucasians showed the highest prevalence of Class II in permanent dentition (23%) and mixed dentition (26%). Class III malocclusion in mixed dentition was highly prevalent among Mongoloids. Conclusion: Worldwide, in mixed and permanent dentitions, Angle Class I malocclusion is more prevalent than Class II, specifically among Africans; the least prevalent was Class III, although higher among Mongoloids in mixed dentition. In vertical dimension, open bite was highest among Mongoloids in mixed dentition. Posterior crossbite was more prevalent in permanent dentition in Europe.

Resumo Objetivo: considerando-se que os estudos disponíveis sobre a prevalência das más oclusões são de base local ou nacional, esse estudo teve como objetivo reunir dados para determinar a distribuição dos tipos de má oclusão em uma escala global, nas dentições permanente e mista. Métodos: foi realizada uma busca eletrônica através das ferramentas de pesquisa do PubMed, Embase e Google Acadêmico, para reunir estudos publicados até dezembro de 2016 sobre a prevalência das más oclusões, tanto na dentição permanente quanto na dentição mista. Resultados: dos 2.977 estudos encontrados, 53 foram analisados. Na dentição permanente, a distribuição mundial das más oclusões de Classe I, II e III foi, respectivamente, de 74,7% [31 - 97%], 19,56% [2 - 63%] e 5,93% [1 - 20%]. Na dentição mista, a distribuição dessas más oclusões foi de 73% [40 - 96%], 23% [2 - 58%] e 4% [0,7 - 13%]. Em relação às más oclusões verticais, observou-se prevalência de 21,98% de sobremordida profunda e 4,93% de mordida aberta. A mordida cruzada posterior afetou 9,39% da amostra. Os africanos mostraram a maior prevalência de Classe I e mordida aberta na dentição permanente (89% e 8%, respectivamente) e na dentição mista (93% e 10% respectivamente), enquanto os caucasianos apresentaram a maior prevalência de Classe II na dentição permanente (23%) e na dentição mista (26%). A má oclusão de Classe III na dentição mista foi mais prevalente entre xantodermas. Conclusão: mundialmente, nas dentições mista e permanente, as más oclusões de Classe I de Angle são mais prevalentes do que as de Classe II, especificamente entre os africanos; a menos prevalente foi a Classe III, ainda que mais prevalente entre os xantodermas na dentição mista. Na dimensão vertical, as mordidas abertas foram mais prevalentes entre xantodermas na dentição mista. A mordida cruzada posterior apresentou maior prevalência na dentição permanente na Europa.

Incidence, severity and orthodontic treatment difficulty index of impacted canines in Saudi population.

BACKGROUND: The objective of this study was to assess the incidence, severity and orthodontic treatment difficulty of impacted maxillary canines in Saudi population. MATERIAL AND METHODS: This retrospective study included an investigation of panoramic radiographs for patients attended College of Dentistry, Jazan University, Saudi Arabia. The incidence of canine impaction and orthodontic treatment difficulty index of maxillary canine impaction was assessed based on; (1) patient age, (2) vertical position, (3) buccolingual position, (4) horizontal position, (5) incisors alignment, (6) canine space, (7) midline coincidence, (8) rotation of impacted tooth. Statistical analyses were calculated by independent Chi-Square test. A P value of less than 0.05 was considered significant. RESULTS: Canine impaction was found in (1.9%) of the population. Bilateral canine impaction was present in 22.3% of the patient with impacted canines. Ninety two percent had impacted maxillary canines only while 7.5% had impacted maxillary canines with other impacted teeth. The ratio of maxillary to mandibular impaction was about 10:1. Females (69.4%) had more impacted canines than males (30.6%) with no significant sex predilection. Orthodontic treatment difficulty index was statistically significant (P ≤0.05) in males more than females. Males revealed statistically significant (P ≤0.05) difficulty regarding canine angulation and the vertical position while females showed significant difficulty regarding dental midline and incisors irregularity or crowding of incisor segment. CONCLUSIONS: Prevalence of maxillary canine impaction in Jazan is within the range of impacted canine in other populations. Females showed more canine impactions than males while the orthodontic treatment difficulty index is more in males than females. Key words:Incidence, Jazan, impaction, maxillary canines, difficulty index.

Three dimensional reliability analyses of currently used methods for assessment of sagittal jaw discrepancy.

BACKGROUND: The objective of this study was to analyse three dimensionally the reliability and correlation of angular and linear measurements in assessment of anteroposterior skeletal discrepancy. MATERIAL AND METHODS: In this retrospective cross sectional study, a sample of 213 subjects were three-dimensionally analysed from cone-beam computed tomography scans. The sample was divided according to three dimensional measurement of anteroposterior relation (ANB angle) into three groups (skeletal Class I, Class II and Class III). The anterior-posterior cephalometric indicators were measured on volumetric images using Anatomage software (InVivo5.2). These measurements included three angular and seven linear measurements. Cross tabulations were performed to correlate the ANB angle with each method. Intra-class Correlation Coefficient (ICC) test was applied for the difference between the two reliability measurements. P value of < 0.05 was considered significant. RESULTS: There was a statistically significant (P<0.05) agreement between all methods used with variability in assessment of different anteroposterior relations. The highest correlation was between ANB and DSOJ (0.913), strong correlation with AB/FH, AB/SN/, MM bisector, AB/PP, Wits appraisal (0.896, 0.890, 0.878, 0.867,and 0.858, respectively), moderate with AD/SN and Beta angle (0.787 and 0.760), and weak correlation with corrected ANB angle (0.550). CONCLUSIONS: Conjunctive usage of ANB angle with DSOJ, AB/FH, AB/SN/, MM bisector, AB/PP and Wits appraisal in 3D cephalometric analysis provide a more reliable and valid indicator of the skeletal anteroposterior relationship. Clinical relevance: Most of orthodontic literature depends on single method (ANB) with its drawbacks in assessment of skeletal discrepancy which is a cardinal factors for proper treatment planning, this study assessed three dimensionally the degree of correlation between all available methods to make clinical judgement more accurate based on more than one method of assessment. Key words:Anteroposterior relationships, ANB angle, Three-dimension, CBCT.

Three-dimensional skeletal, dentoalveolar and temporomandibular joint changes produced by Twin Block functional appliance.

INTRODUCTION: The aim of this study was to three-dimensionally analyze the net skeletal, dental, and temporomandibular joint (TMJ) treatment changes using Twin Block functional therapy in comparison to untreated subjects. MATERIALS AND METHODS: The study (Twin Block) group comprised 22 female patients with skeletal Class II malocclusion due to mandibular retrusion. A total of 18 skeletal Class II untreated female subjects were included as controls. Skeletal, dental, and TMJ changes were evaluated using pre- and posttreatment/observational by cone beam computed tomography (CBCT) images. The treatment changes were compared with the growth changes observed in the control group using independent t­tests. RESULTS: Compared to the changes induced by normal growth, the effective mandibular length, ramus, and corpus lengths increased by 3.19, 3.47, and 2.69 mm (P < 0.001 for all), respectively. The maxillary and mandibular incisors inclination and position were significantly reduced and increased, respectively (P < 0.001). The maxillary first molars were significantly moved distally and intruded by 1 and 0.36 mm, respectively, while the lower first molars moved mesially and intruded by 2.18 and 0.59 mm, respectively. There was a significant change in the condylar dimensions: increase in length, width, and height by 1.28, 0.88, 1.59 on the right and by 1.60, 0.53, and 1.10 mm on the left sides, respectively. There was significant forward positioning of the right and left condyle by 1.5 and 1.3 mm, respectively. CONCLUSIONS: Treatment with the Twin Block functional appliance results in significant skeletal, dentoalveolar, and condylar changes in both dimensions and positions.

A novel approach for treatment of skeletal Class II malocclusion: Miniplates-based skeletal anchorage.

INTRODUCTION: The objective of this study was to evaluate the effect of a new approach-bimaxillary miniplates-based skeletal anchorage-in the treatment of skeletal Class II malocclusion compared with untreated subjects. METHODS: The study (miniplates) group comprised 28 patients (14 boys, 14 girls) with skeletal Class II malocclusion due to mandibular retrusion, with a mean age of 11.83 years. After 0.017 × 0.025-in stainless steel archwires were placed in both arches, 4 miniplates were fixed bilaterally, 2 in the maxillary anterior areas and 2 in the mandibular posterior areas, and used for skeletal treatment with elastics. Twenty-four Class II untreated subjects (11 boys, 13 girls), with a mean age of 11.75 years, were included as controls. Skeletal and dental changes were evaluated using pretreatment and posttreatment or observational lateral cephalometric radiographs. The treatment changes were compared with the growth changes observed in the control group using independent t tests. RESULTS: Compared with the minimal changes induced by growth in the control group, the skeletal changes induced by miniplates were more obvious. The mandibular length increased significantly (3 mm), and the mandible moved forward, with a significant restraint in the sagittal position of the maxilla (P <0.001). The overjet correction (-4.26 mm) was found to be a net result of skeletal changes (A-Y-axis = -1.18 mm and B-Y-axis = 3.83 mm). The mandibular plane was significantly decreased by 2.75° (P <0.001). CONCLUSIONS: This new technique, bimaxillary miniplates-based skeletal anchorage, is an effective method for treating patients with skeletal Class II malocclusions through obvious skeletal, but minimal dentoalveolar, changes.