Dental Asymmetry Research Articles

Dimensions of central incisors, canines, and first molars in subjects with Down syndrome measured on cone-beam computed tomographs

The literature on tooth dimensions in subjects with Down syndrome (DS) is scarce. To our knowledge, no studies have yet been published in which the morphometry of the teeth in DS subjects has been determined using computed tomography. The study group consisted of 40 subjects with DS, aged 10 to 40years. An age- and sex-matched control group was selected. Cone-beam computed tomography images were retrieved from the archive of the Santiago de Compostela University in Spain. The maxillary central incisors, canines, and first molars were evaluated. The following variables were analyzed: overall tooth length, crown height, root length, mesiodistal diameter, vestibular-palatine diameter, crown-to-root ratio, and cervical circumference. The teeth of subjects with DS were smaller than those of the controls, although the crown-to-root ratio was maintained. No clear sexual dimorphism was detected, but the root lengths of the incisors were greater in male subjects. Crown height, mesiodistal diameter, and crown-to-root ratio showed progressive reductions with age. There appeared to be a degree of "fluctuating dental asymmetry" with respect to vestibular-palatine diameter and cervical circumference. Our findings confirm microdontia of the permanent teeth and progressive reductions in tooth sizes with age in persons with DS. These variations might be relevant to orthodontic treatment planning.

Longitudinal evaluation of dental arch asymmetry in Class II subdivision malocclusion with 3-dimensional digital models

Class II subdivision malocclusions with their asymmetric occlusal relationships often pose treatment difficulties. The aim of this study was to evaluate the longitudinal changes of dental arch asymmetry in untreated subjects with Class II subdivision malocclusion. From 706 files from the University of Michigan Growth Study, longitudinal records of 17 untreated subjects with Class II subdivision malocclusion were included this study. Dental arch changes at 3 consecutive longitudinal intervals, defined by the cervical vertebral maturation method, were analyzed on digital dental models. The average ages of the subjects were 12.4, 15.1, and 19.1years at the 3 time periods, respectively. Maxillary and mandibular reference lines were constructed and used for the intra-arch asymmetry measurements. The Friedman test and analysis of variance with repeated measures were used to determine dental arch asymmetries at the P<0.05 level. All subjects were found to have a type 1 Class II subdivision malocclusion characterized by distal positioning of the mandibular first molar on the Class II side. No statistically significant intra-arch asymmetry changes were found for the maxillary and mandibular dental arches in any time period. Between the baseline and the final follow-up, the data indicated decreases in maxillary and mandibular intercanine arch widths and arch lengths symmetrically. The results of this study indicate that the dental arch asymmetry in patients with Class II subdivision malocclusions did not improve or worsen with growth.

Dental arch asymmetry.

Objective:This study was conducted to assess the dental arch asymmetry in a Yemeni sample aged (18-25) years.Materials and Methods:The investigation involved clinical examination of 1479 adults; only 253 (129 females, 124 males) out of the total sample were selected to fulfill the criteria for the study sample. Study models were constructed and evaluated to measure mandibular arch dimensions. Three linear distances were utilized on each side on the dental arch: Incisal-canine distance, canine-molar distance and incisal-molar distance, which represent the dental arch segmental measurements.Results:When applying “t-test” at P < 0.05, no significant differences were found between the right and left canine-molar, incisal-canine and incisal-molar distances in both dental arches for both sexes. The greater variation (0.30 mm) was observed between right and left canine-molar distance in the maxillary dental arch in male and the smaller (0.04 mm) in the mandibular dental arch between the right and left canine-molar distance in females.Conclusion:The findings of the present study revealed a symmetrical pattern of dental arches, since the right and left sides showed no statistically significant difference. In general, it can be observed that the measurements related to the central incisors and canines have the widest range of reading and give the impression that the location of central incisor and canines to each other and to other teeth is the strongest factor in determining the dental arch asymmetry.

Reliability of CBCT in the diagnosis of dental asymmetry.

ObjectiveThe aim of this study was to validate a method used to assess dental asymmetry, in relation to the skeletal midline, by means of CBCT.MethodsTen patients who had CBCT scans taken were randomly selected for this study. Five different observers repeated 10 landmarks (x, y and z variables for each) and 12 linear measurements within 10 days. Measurements were taken in both arches to evaluate symmetry of first molars, canines and dental midline in relation to the skeletal midline. Intraclass correlation coefficient (ICC) was carried out to assess intra- and interobserver reliability for landmarks and distances. Average mean difference was also assessed to check measurement errors between observers.ResultsICC landmarks was ≥ 0.9 for 27 (90%) and 25 (83%) variables for intra- and interobserver, respectively. ICC for distances was ≥ 0.9 for 7 (58%) and 5 (42%), respectively. All ICC landmarks for distances were >0.75 for both intra- and interobserver. The mean difference between observers was ≤ 0.6 mm for all the distances.ConclusionThe method used to assess dental asymmetry by means of CBCT is valid. Measurements of molars, canines and dental midline symmetry with the skeletal midline are reproducible and reliable when taken by means of CBCT and by different operators.

Classification and treatment of Class II subdivision malocclusions

Patients with Class II subdivision malocclusions are a challenge for clinicians because reestablishing symmetry in 1 arch or both arches is often a treatment goal. In patients with mandibular skeletal asymmetry, surgery is often a treatment option. However, patients may be unwilling to undergo surgery, and other options might have to be considered. The aim of this study was to evaluate the etiologies and outcomes of Class II subdivision patients treated at the University of Washington graduate orthodontic clinic in Seattle from 1995 through2011. A search of patients treated between 1995 and 2011 resulted in the identification of 110 consecutively treated Class II subdivision subjects with complete records. Ninety-eight subjects could be classified into 1 of 3 groups, based on midline position and dental or skeletal etiology. Initial and final models were used to measure the peer assessment rating scores, midlines, overjet, overbite, and molar positions. Initial and final cephalograms were traced and measured. Charts were reviewed for information regarding treatment. Twenty-five percent of the 98 subjects had their maxillary and mandibular midlines coincident with the facial midline; their asymmetries were due to a maxillary posterior dental asymmetry. Another 15% had maxillary midlines deviated from their facial midlines, caused by maxillary anterior and posterior dental asymmetry. About 50% of the subjects had mandibular midlines that were not coincident with their facial midlines, and most of them exhibited some degree of mandibular skeletal asymmetry. Over the past 15 years, treatment strategies used at the University of Washington indicated trends toward less surgery, fewer extractions, less use of headgear, and more reliance on fixed functional appliances. Ideal correction of midlines was not always achieved, especially in patients with mandibular skeletal asymmetry, with undercorrection occurring more commonly than overcorrection. Final peer assessment rating scores were comparable, regardless of the origin of the asymmetry or the extractions status. Mandibular incisor proclination was increased when fixed functional appliances were used, as well as when a Class I molar relationship was the target for the Class II side. Class II subdivision malocclusions were grouped into 3 main categories; the largest category was mandibular asymmetry. Interesting trends were noted with regard to treatment strategies, midline and molar corrections, and mandibular incisor proclination.

Noninvasive and multidisciplinary approach to the functional and esthetic rehabilitation of amelogenesis imperfecta: a pediatric case report.

Case Report. An 8-year-old girl with amelogenesis imperfecta (AI) reported unsatisfactory aesthetics, difficulty in mastication, and dental hypersensitivity. The intraoral examination observed mixed dentition, malocclusion in anteroposterior relationships, anterior open bite, and dental asymmetry. A hypoplastic form of AI was diagnosed in the permanent dentition. A multidisciplinary planning was performed and divided into preventive, orthopedic, and rehabilitation stages. Initially, preventive treatment was implemented, with fluoride varnish applications, in order to protect the fragile enamel and reduce the dental sensitivity. In the second stage, the patient received an interceptive orthopedic treatment to improve cross-relationship of the arches during six months. Finally, the rehabilitation treatment was executed to establish the vertical dimension. In the posterior teeth, indirect composite resin crowns were performed with minimally invasive dental preparation. Direct composite resin restorations were used to improve the appearance of anterior teeth. Follow-Up. The follow-up was carried out after 3, 6, 12, and 18 months. After 18 months of follow-up, The restoration of integrity, oral hygiene, and patient satisfaction were observed . Conclusion. Successful reduction of the dental hypersensitivity and improvement of the aesthetic and functional aspects as well as quality of life were observed.

Evaluation of Asymmetries associated with Class II subdivision malocclusions and Normal occlusion.

Aim: The objective of this study was to compare the dental and skeletal asymmetry seen in subjects with Class II subdivision malocclusion and normal occlusion. Materials and Methods: The sample consisted of 30 subjects in each group with Angle Class II subdivision malocclusions and with Angle Class I malocclusions. Postero-Anterior cephalographs were obtained from each subject. The cephalometric measurements were obtained according to the method described by Grummon's and Van de Coppell. Results are expressed as Mean and Standard Deviation. Differences between two groups are compared by unpaired t test. P = 0.05 or less was considered as statistically significant. Results: Sub-division cases exhibited 10.5% more asymmetry with angular measurements and exhibited 38% more asymmetry with linear measurements as compared with normal group. Conclusion: There was a significant amount of radiographic mandibular asymmetry in relation to Class II subdivision malocclusions in general. As a consequence of the more frequent asymmetry in the lower third of face, the mandibular dental midline and the antegonial angle were deviated on the Class II side, as evaluated on the postero-Anterior radiograph.

Dental Arch Asymmetry in Mixed Dentition in Palestinian Children

<b>Introduction:</b> To quantify and describe dental arch asymmetry in Palestinian group in mixed dentition.<br> <b>Materials and Methods:</b> Dental casts were taken for 40 subjects in mixed dentition (6-12) years of both sexes and arch asymmetry was measured using a computer-aided system.<br> <b>Results:</b> Anteroposterior asymmetry was not prevalent as transverse asymmetry, anteroposterior asymmetry in the mixed dentition increased in the posterior direction, neither significant sex difference nor significant age difference was found.<br><b>Conclusion:</b> Asymmetry in the anteroposterior is not prevalent as in the transverse direction. Anteroposterior asymmetry in the mixed dentition increases in the posterior direction. There is insignificant difference between the mean values of male and female groups and between the two age groups. Asymmetry is a dominant character in its expression and doesn't relate to sex and age.

Laypersons’ Perception of Facial and Dental Asymmetries

The purpose of this article was to determine the individual visual perception thresholds of certain facial and dental discrepancies for a symmetric face model (SFM). A facial photograph of a female subject's smile was digitally manipulated into an artificially symmetric picture. Modifications were made on the SFM for shifts in the dental midline, nose, and chin (group 1) and cants of dental midline and incisal plane (group 2), resulting in a total of 24 different images divided into two groups. One-hundred randomly selected laypersons divided into two groups were used to evaluate each image according to their own personal beauty and esthetic criteria using a visual analog scale. The visual perception thresholds found for the SFM were 2 mm for a dental midline shift, 4 mm for nose deviation, 5 degrees for dental midline cant, and 3 degrees for frontal incisal plane cant. Chin deviations of 6 mm or less were not noticed. Dental midline shift, nose deviation, dental midline cant, and incisal plane cant relative to an SFM have an impact on the perception of facial attractiveness. Chin deviations did not have a statistically significant impact.

Orthodontic Management of a Case with Skeletal Class III Malocclusion

Class III malocclusions are considered one of the most complex and difficult orthodontic problems to diagnose and treat. Skeletal and /or dental asymmetries in patient presenting with Class III malocclusion can worsen the prognosis recognizing the dentoalveolar and skeletal characteristics of class III malocclusion and their treatment possibilities is essential for a favorable nonsurgical correction. Therefore, this case presents a nonsurgical extraction approach to class III malocclusion treatment which can significantly improve the occlusion and facial deformities. A male patient of 18 yrs attended a private dental office at Dhaka, Bangladesh with the complain of aesthetic problem. On examination, incisor, canine and molar relationships were found Class III on both sides with palatally placed upper central incisors and crowding on both anterior segments. The case was treated orthodontically. It tooks nearly 18 months to complete the treatment. The patient was happy with the new appearance and function. DOI: http://dx.doi.org/10.3329/cdcj.v10i2.16349 City Dent. Coll. J Voume-10, Number-2, July-2013

Orthodontic management of a case with skeletal Class III malocclusion

Class III malocclusions are considered one of the most complex and difficult orthodontic problems to diagnose and treat. Skeletal and/or dental asymmetries in patients presenting with Class III malocclusions can worsen the prognosis. Recognizing the dentoalveolar and skeletal characteristics of Class III malocclusions and their treatment possibilities is essential for a favorable nonsurgical correction. Therefore, this article presents a nonsurgical extraction approach to Class III malocclusion treatment which can significantly improve the occlusal and facial discrepancies. DOI: http://dx.doi.org/10.3329/bjodfo.v2i1.15999 Ban J Orthod &amp; Dentofac Orthop, October 2011; Vol-2, No.1, 20-25

Evaluation of skeletal and dental asymmetries in Angle Class II subdivision malocclusions with cone-beam computed tomography

The purpose of this study was to determine whether Angle Class II subdivision malocclusions have skeletal or dental asymmetries between the Class II and Class I sides. A sample of 54 untreated Angle Class II subdivision patients with pretreatment photos and cone-beam computed tomography (CBCT) scans was used. The photos were used to identify the Class II subdivision malocclusion and to record the amount of crowding per quadrant. Landmarks were plotted on each CBCT volume so that direct 3-dimensional measurements could be made to compare the positions and dimensions of the skeletal and dental structures on the Class II side vs the Class I side. Significant differences were found for 2 skeletal measurements: the position of the maxilla relative to the cranial base, and the mandibular dimension from the mandibular foramen to the mental foramen. Statistically significant dental differences were found for the position of the mandibular first molars and canines in relation to the maxilla and the mandible. Statistically significant differences were found for the maxillary first molars and canines in relation to the mandible. There were significant skeletal and dental differences between the Class I and Class II sides. The dental asymmetries accounted for about two thirds of the total asymmetry.

Significance of crown shape in the replacement of a central incisor with a single implant-supported crown.

When utilizing a single implant-supported crown to replace a central incisor, understanding the final shape of the implant restoration is an important factor to help achieve a successful esthetic outcome. In today's dentistry, tooth shape is a critical factor when dental implant prostheses are considered in the esthetic zone. The major esthetic goal for this type of restoration is to achieve the closest possible symmetry with the adjacent tooth, both at the soft and at the hard tissue levels. The goal of this study was to objectively analyze the significance of natural crown shape when replacing a central incisor with a single implant-supported crown. In this study, we investigated the shape of the crowns of maxillary central incisors in 60 individuals who presented to our clinics with an untreatable central incisor. The presence of a dental diastema, "black triangle," presence or absence of gingival symmetry, and the presence or absence of dental symmetry were recorded in the pre- and postoperative photographs. Out of 60 patients, 33.3% had triangular-shaped crowns, 16.6% square/tapered, and 50% square-shaped crown form. After treatment was rendered, 65% of the triangular group, 40% of the square/tapered group, and 13.3% of the square group required an additional restoration on the adjacent central incisor in order to fulfill the esthetic needs of the patients. Data analysis revealed that if there is a "black triangle," a diastema, or presence of dental or gingival asymmetry, an additional restoration on the adjacent central incisor is often required in order to fulfill esthetic goals. The additional restoration is highly recommended in situations with a triangular crown shape, while it is suggested in cases of square/tapered and square tooth shapes in the presence of a dental diastema.

Orthodontic and orthognathic management of a complex mandibular asymmetry

The application of a combined surgical-orthodontic procedure for the treatment of major facial deformities (eg, asymmetries) and associated malocclusions has become an increasingly prevalent treatment modality over the past few decades. Development of sound conjoint treatment principles made possible the correction of skeletal and dental dysplasias that were unyielding to either surgical or orthodontic treatment alone. The presence and severity of dentofacial asymmetries has been the subject of many commentaries and investigations. Treatment of facial asymmetry has always been a challenge with respect to the cause and the rationale behind the corrective procedures adopted. This case report describes a 23-year-old male patient whose chief complaint was attributed solely to the clinically discernible facial asymmetry. A combined orthodontic and surgical approach was done to correct both the dental and skeletal asymmetry. The reasons for selecting this treatment protocol and the 5-year postretention stability of the final results obtained are highlighted in this report.

Angle Class III malocclusion treated with mandibular first molar extractions

A Class III malocclusion associated with dental asymmetry is a complex diagnostic and treatment problem in orthodontics. The goals of maintaining or improving the facial profile and achieving good function are decisive factors when considering whether to plan a surgical or a nonsurgical treatment approach. A fixed appliance in combination with extractions could be considered for nonsurgical management of this type of malocclusion in the permanent dentition. This article presents the results of an orthodontic approach to a Class III subdivision malocclusion in an adult treated with mandibular first molar extractions. The extractions provided the space needed to correct the overjet and overbite and to improve the intercuspation.

Evaluation of the dental arch asymmetry in natural normal occlusion and Class II malocclusion individuals

Objective: To verify the presence and degree of asymmetry of dental arches in Brazilian individuals with natural normal occlusion and Class II, Divisions 1 and 2 malocclusions. Methods: The study evaluated the symmetry of the maxillary and mandibular dental arches of 180 pairs of dental casts, divided into: Group I = 60 pairs of natural normal occlusion individuals; Group II = 60 pairs of Class II, Division 1 malocclusion individuals; and Group III = 60 pairs of Class II, Division 2 malocclusion individuals. A device was used to measure dental midline deviation and the canine tip in the dental arches (in degrees). It was also verified the distance of the upper canines from the palatal suture, intercanine distance, and anteroposterior upper and lower first molar position. Results: Dental arches of individuals from all groups presented asymmetry, regardless of the presence of malocclusion. Group I showed a lower asymmetry degree in relation to Groups II and III. The asymmetry in Groups II and III was similar. Conclusion: The dental arches of individuals with natural normal occlusion and with Class II, Division 1 and Division 2 malocclusions showed asymmetry. The asymmetry degree was higher in the mandibular dental arches than in the maxillary dental arches in all 3 evaluated groups.

Atypical orthodontic extraction pattern managed by differential en-masse retraction against a temporary skeletal anchorage device in the treatment of bimaxillary protrusion

This report introduces an innovative treatment approach of selecting atypical and unconventional teeth for orthodontic extraction without compromising the quality of treatment outcomes by using temporary skeletal anchorage devices in patients with bimaxillary protrusion. Both patients introduced in this report had solid Class I molar relationships with bimaxillary anterior protrusion without facial or dental midline asymmetry. Their chief concerns were significant facial convexity, which conventionally requires the extraction of all 4 first premolars. However, 3 second premolars and 1 first premolar were removed in the first patient, and 2 second premolars and 2 first premolars were removed in the second patient. All second premolars extracted had previously had root canal treatment and large prosthodontic restorations, which resulted in a compromised short lifespan of the teeth relative to the natural dentition. To manage these cases of asymmetric extraction space in a symmetric dental and skeletal environment, 2 mini-implants were placed in the posterior maxillary interradicular spaces, 1 on each side. Despite the unusual asymmetric extraction of teeth, superimposition of the pretreatment and posttreatment cephalometric tracings shows excellent treatment outcomes of facial convexity reduction by asymetric maximum retraction of the anterior teeth with no change in the molar relationships.

Temporal Tendinitis: A Modified Levandoski Panoramic Analysis of 21 Cases

In 1993, Levandoski1 published the details of a system to analyze panoramic radiographs and especially, the temporomandibular joints. Piedra2 expanded the work of Levandoski to analyze facial and dental asymmetries. In this brief treatise, the disorder of temporal tendinitis was explored. A modified Levandoski technique was used to compare the lengths of the coronoid and condylar processes in an attempt to demonstrate how the panoramic radiograph can be simply used in the diagnosis of temporal tendinitis in the retrospective study of 21 such cases. Conclusions: a total of 18 of the 21 coronoid processes (85%) were equal to or longer than their condylar process counterparts, thus indicating that a panoramic radiograph may be useful in the diagnosis of temporal tendinitis.

Editor's Comment and Q&A: Skeletal and dental asymmetries in Class II subdivision malocclusions using cone-beam computed tomography

Introduction The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography. Methods Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups. Results Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side. Conclusions The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors. The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography. Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups. Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side. The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors.

Skeletal and dental asymmetries in Class II subdivision malocclusions using cone-beam computed tomography

The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography. Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups. Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side. The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors.