Mandibular Dental Arch Form Research Articles

Relationship between dental and basal arch forms in mandibular anterior crowding

Positive correlations between the mandibular dental and basal arch forms in patients with minimum crowding have been observed; however, the relationship in orthodontic patients with mandibular anterior crowding (MnAC) remains unclear. Therefore, we evaluated this relationship in patients with MnAC requiring premolar extraction. Thirty women with normal occlusion (mean age, 20.6±2.5years) and 30 women with Class I MnAC (mean age, 20.3±2.9years) were selected as control and MnAC groups, respectively. The widths and depths of the mandibular dental and basal arches at the FA and WALA points were measured and compared between groups. Relationships between the arch widths at the FA and WALA points were analyzed by Pearson correlation coefficient. Larger variances were found for dental arch widths at canine and premolars and depth at canine in the MnAC group. Positive correlations were observed between dental and corresponding basal arch widths for both groups, except at the canine in the MnAC group, and higher correlations were observed between dental arch widths for all teeth except the first molar and basal arch widths for posterior adjacent teeth when comparing the corresponding basal arch widths. The positive correlations observed between the dental and basal arch widths suggest the basal arch widths at the posterior adjacent tooth can be used as an additional reference to create an individualized postorthodontic dental arch form for MnAC patients.

Determination of Mandibular Arch Form During Mixed Dentition Using Custom Made Template in Sulaimani Governorate

Objectives: The dental arch form and dimensions change continuously and systematically during human growth and development, but this decreases adulthood. During mixed dentition, changes in dental arch forms and the occlusion occur due to teeth movements and growth of the alveolar bone. Usually, changes in the mandibular arch are followed by changes in the maxillary arch. The research aimed to determine the most frequent mandibular dental arch form and its relationship with gender. 
 Methods: The mandibular arch forms of 115 schoolchildren with mixed dentition were examined using their dental casts. Adobe Photoshop© (21.0.0, 2019) program was used to construct a template from photographs of the casts and printed on transparent paper to overlay the casts. The data were collected and calculated using statistical software to determine the frequencies of different arch forms among the studied sample. 
 Results: The sample was composed of 61 males (53%) and 54 females (47%). The oval arch form was the most frequent type with 70 cases (60.9%), followed by the square arch form with 38 cases (33%), and finally the tapered arch form with 7 cases (6.1%). No significant relationship was found between the arch form and the gender of the participants. 
 Conclusions: Oval arch form was the most predominant type of arch form of the mandible in the mixed dentition, and there was no relationship with gender.

Association between Intercanine Width and Mandibular Dental Arch Forms.

A descriptive cross-sectional study was conducted to investigate the association between intercanine width and the mandibular arch form in 109 dentate subjects, who visited Orthodontics Department from October 2018 to December 2019. Using Vernier caliper, the intercanine width was measured as the distance between the left and right canines on each cast with the arch form, also categorized as tapered, square or ovoid, using predefined criteria. Spearman's rank correlation demonstrated highly significant association between intercanine width and mandibular dental arch forms, with p value of 0.005. Key Words: Dentate subjects, Mandibular arch forms, Inter-canine width, Sexual dimorphism, Mandibular dental cast.

Maxillary and mandibular dental arch forms in a Jordanian population with normal occlusion

BackgroundEthnic background has been claimed to affect arch form. The purpose of this study was to describe and elucidate the maxillary and mandibular arch forms in Jordanian population and to develop a classification method for these forms which could be employed to construct orthodontic archwires accordingly.MethodsThe sample was comprised of study casts of five hundred and twenty subjects (231 males and 289 females with a mean age of 15.4 ± 1.02 years). All subjects had permanent dentition with normal occlusion. A mathematical method associated with a polynomial function of 6th degree was employed to assess the dental arch forms. The resultant arch forms were classified into 5 groups for both the maxilla and mandible utilizing a computer software with special code designed for this study. Each group was subdivided into 3 subgroup sizes namely: small, medium, and large.ResultsCatenary arch form was found in 47% and 41.2% (p ˂ 0.01) of maxilla and mandible arch forms, respectively. Form 2 (which is halfway between ellipse and U-shaped arch form) was found in 27.7% and 26.7%. Medium size arch form was found in 55.4% of the maxillary and 65.6% of the mandibular arch forms.ConclusionCatenary arch form was the most prevalent arch form, followed by wide elliptical form. The other forms, which included tudor arch, tapered equilateral and quadrangular forms were less frequent. Regarding size, the medium size was the most prevalent among the studied samples.

Selected Orthodontic Principles for Management of Cranio-Maxillofacial Deformities.

An understanding of fundamental orthodontic principles involving diagnosis, treatment planning, and clinical strategies is essential for achieving successful outcomes in the treatment of craniofacial patients, particularly cleft lip/palate. This article focuses on: customizing a mandibular dental arch form using the WALA ridge; accurately diagnosing the maxillary skeletal transverse dimension (cusp to cusp/fossa to fossa); coordinating the upper dental arch with the lower; using a smiling profile and glabella vertical to assess anteroposterior jaw position; and leveling the mandibular curve of Spee while considering the lower one-third of the face. These concepts influence treatment outcomes to the extent they are used.

Transverse adjustment of preformed stainless steel archwires to the dental arch form

PurposeStable orthodontic treatment results require the preservation of the pretreatment mandibular dental arch form. Therefore, this study aimed to evaluate the amount of transverse adjustment of preformed stainless steel archwires require to fit the dental arch form. Materials and methodsA fourth-order polynomial curve was applied to the 30 normal mandibular dental arches, and interpolated widths at the mean depths at the canine, first and second premolars, and first molar were measured. Widths of 42 types of 0.016-in. stainless steel preformed archwires were measured at the same mean depths. The widths of the dental arch and archwires were compared by the Mann–Whitney U test. Transverse adjustment values as the difference between dental and archwire widths for each tooth from the canine to first molar were calculated for each archwire and compared between tooth types. Correlation coefficients between tooth types were also analyzed. ResultsPreformed archwire width was significantly narrower than the dental arch. Significant difference between transverse adjustment values between each tooth type were found except between canine and first premolar. Significant correlations between each tooth types were also observed. ConclusionTo reduce these adjustments, preformed stainless steel archwires that are designed to be approximately 1–2mm at the canine, 1–3mm at first premolar, 2–4mm at second premolar, and 3–6mm at first molar wider in the transverse dimension could be clinically recommended.

Mandibular dental-basal arch forms in skeletal Class III patients with mandibular prognathism

PurposeThe aims of this study were to investigate the relationship of the labio-lingual position of the mandibular dental arch form to the corresponding basal arch form using three-dimensional dental cast analysis in skeletal Class III patients with mandibular prognathism who were indicated for mandibular setback surgery and to compare the results with those of participants with orthodontically untreated Angle Class I normal occlusion. Materials and methodsMandibular dental casts of 56 skeletal Class III patients with mandibular prognathism (MP-group) and 56 control participants (C-group) with Angle Class I normal occlusion were examined. To evaluate dental and basal arch forms, the FA and WALA points, respectively, were located, and eight linear measurements and six ratio variables were calculated. Relationships between the dental and basal arch forms were evaluated and compared between the groups. ResultsDental arch widths, basal arch widths and depths, and the basal arch ratio were greater and the dental arch depth was smaller in the MP-group than in the C-group. The FA points in the MP-group were more lingually positioned from the central incisor to the second premolar and were more buccally positioned for the first molar. Significant positive correlations were observed between the dental and basal arch dimensions and ratios in both groups. ConclusionThe observed morphological characteristics of the dental and basal arch forms and dental arch form-basal arch form relationships in the MP-group suggest the possibility of using dental cast analysis to identify an individualized therapeutic target for dental decompensation.

フーリエ級数を用いて再現した歯列弓形態による上下顎歯列弓の形態比較(大阪歯科大学大学院歯学研究科博士(歯学)学位論文内容要旨および論文審査結果要旨の公表)

フーリエ級数を用いて再現した歯列弓形態による上下顎歯列弓の形態比較(大阪歯科大学大学院歯学研究科博士(歯学)学位論文内容要旨および論文審査結果要旨の公表)

Dental arches dimensions, forms and its association to facial types in a sample of Iraqi adults with skeletal and dental class II-division 1 and class III malocclusion(A cross sectional study)

Background: The association between facial types and dental arches forms has considerable implications in orthodontic diagnosis and treatment planning. The aim was to establish the maxillary and mandibular dental arches width and length in skeletal and dental class II division 1 and class III malocclusion groups, find out the most frequent dental arch form and facial type and the association between them and to check the gender differences. Materials and Methods: Frontal and lateral facial photographs and maxillary and mandibular occlussal photographs for 90 iraqi subjects with age 18-25 years old (45 males and 45 females) divided equally into three groups, the 1st group with class II division 1malocclusion (overjet more than 3mm but less than or equal to 6mm), the 2nd group with class II division 1malocclusion (overjet more than 6mm) while the 3rd group with class III malocclusion (edge to edge or reverse overjet).Six linear measurements for each maxillary and mandibular dental cast photographs and two liner measurements for frontal and profile facial photographs was analyzed with (AUTO CAD 2013), which simplified the analyzing process and reduced the time and effort spent on taking measurements directly from the records to facilitate work and to gain more accurate results. Results: All the mean value of dental arches and facial measurements were higher in male than female, the most frequent maxillary and mandibular dental arch form in the three groups was the mid arch form follow by the narrow then the wide arch form except in the mandibular dental arch of the 3rd group it follow by the wide then the narrow arch form.The most frequent facial type in the 1st group is the Mesoprosopic one,followed by the Leptoprosopic then the Euryprosopic face type while in the 2nd and 3rd group the most frequent facial type is the Leptoprosopic, follow by the Mesoprosopic then the Euryprosopic facial type. An association was found between mid arch form and the Mesoprosopic face type in the 1st group, while no clear association was found between dental arch form and facial type in the 2nd and 3rd group for both genders. Conclusions: It was concluded that there was an association between facial type and dental arch form in subject with class II division 1malocclusion (overjet not more than 6mm), while in subject with class II division 1malocclusion (overjet more than 6mm) or with class III malocclusion (edge to edge or reverse overjet) no clear association was found between dental arch form and facial type.

<b> Is there any association between facial type and mandibular dental arch form in subjects with normal occlusion? </b>

The aim of this study was investigate the association between the mandibular arch morphology and the facial type of Brazilian Caucasians with natural normal occlusion. For this, we used a sample comprised of lateral radiographs and respective dental casts of 51 individuals (21 male and 30 female), presenting at least 4 of the 6 Andrews' keys to normal occlusion without previous orthodontic treatment. Angle's first molar relationship was considered indispensable for the sample. The facial type was defined by two cephalometric measurements (SN.SGn and SN.GoGn). After scanning the models (3D) and radiographs, the images were evaluated by 12 orthodontists. A modified Kappa test evaluated the agreement between examiners to classify the morphology of the dental arch. The chi-square test was used to verify the association between the facial type (dolichofacial, mesofacial, or brachyfacial) and the dental arch morphology (square, oval, or tapered), using significance level of 5%. Casual and systematic errors (p > 0.05) showed no significant results and the Kappa test showed significant agreement among examiners for the dental arch form (0.55) with a p < 0.001, considered as 'moderate'. The chi- square test indicated no significant association. The null hypothesis was accepted, as the facial type was not associated with dental arch morphology in individuals with normal occlusion.

The study of essential factors that affect mandibular dental arch forms by cluster analysis

The study of essential factors that affect mandibular dental arch forms by cluster analysis

Effect of Preorthodontic Trainer in Mixed Dentition

Background. This paper reports a case with end-on-molar relation with maxillary anterior teeth proclination, lower anterior teeth crowding, and deep bite. The case was successfully treated in a short span. Clinically significant improvement in the dimensions of the maxillary and mandibular dental arch forms and sufficient space for the eruption of permanent teeth was observed. Conclusion. Therefore, it can be concluded that preorthodontic trainer is a valid treatment of choice in mixed dentition where transverse expansion is a part of the treatment plan, as the results obtained are within short period of time and have less chances of relapse, because the correction of a malocclusion is by elimination of soft tissue dysfunction.

Comparison between dental and basal arch forms in normal occlusion and Class III malocclusions utilizing cone-beam computed tomography

ObjectiveThe purpose of this study was to investigate the relationship between the mandibular dental and basal arch forms in subjects with normal occlusion and compare them with those of Class III malocclusion using cone-beam computed tomography (CBCT).MethodsCBCT images of 32 normal occlusion (19 males, 13 females; 24.3 years) and 33 Class III malocclusion subjects (20 males, 13 females, 22.2 years) were selected. Facial axis and root center points were identified from the left to right mandibular first molars. Distances between the facial axis and root center points for each tooth were calculated, and 4 linear and 2 ratio variables were measured and calculated for each arch form. The variables were compared between groups by independent t-test. Pearson correlation coefficient was applied to assess the relationships between dental and basal variables within each group.ResultsThe mandibular dental and basal intercanine widths were significantly greater in the Class III group than in normal occlusion subjects (p < 0.05). The dental and basal intercanine widths as well as the dental and basal intermolar widths were strongly correlated in normal occlusion and moderately correlated in Class III malocclusion.ConclusionsThe dental arch form demon strated a strong positive correlation with the basal arch form in the normal occlusion group and moderate correlation in the Class III malocclusion group. These results might be helpful for clinicians to have a better understanding of the importance of basal arch form in the alveolar bone.

Correlation between maxillary central incisor crown morphology and mandibular dental arch form in normal occlusion subjects

The aim of this study was to evaluate the correlation between the morphology of the mandibular dental arch and the maxillary central incisor crown. Cast models from 51 Caucasian individuals, older than 15 years, with optimal occlusion, no previous orthodontic treatment, featuring 4 of the 6 keys to normal occlusion by Andrews (the first being mandatory) were observed. The models were digitalized using a 3D scanner, and images of the maxillary central incisor and mandibular dental arch were obtained. These were printed and placed in an album below pre-set models of arches and dental crowns, and distributed to 12 dental surgeons, who were asked to choose which shape was most in accordance with the models and crown presented. The Kappa test was performed to evaluate the concordance among evaluators while the chi-square test was used to verify the association between the dental arch and central incisor morphology, at a 5% significance level. The Kappa test showed moderate agreement among evaluators for both variables of this study, and the chi-square test showed no significant association between tooth shape and mandibular dental arch morphology. It may be concluded that the use of arch morphology as a diagnostic method to determine the shape of the maxillary central incisor is not appropriate. Further research is necessary to assess tooth shape using a stricter scientific basis.

Mandibular dental and basal arch forms in Japanese Angle Class I malocclusion with crowding

Mandibular dental and basal arch forms in Japanese Angle Class I malocclusion with crowding

Subjective classification and objective analysis of the mandibular dental-arch form of orthodontic patients

Our objective was to evaluate the relationship between subjective classification of dental-arch shape, objective analyses via arch-width measurements, and the fitting with the fourth-order polynomial equation. Twenty-seven pretreatment mandibular dental casts (from 13 males and 14 females; ages, 12-31 years) were selected. Standardized photographs of the arches were serially organized from tapered to square by 10 examiners. The mean position in the ranking of each cast was calculated as a rank of each arch form. The dental casts were analyzed with a 3-dimensional laser scanning system. Dental-arch widths at the canines and molars were measured, and then a fourth-order polynomial equation was fit to each arch. Correlations between the rank of arch shape and the objective measurements were statistically tested. The arch forms having the greatest variations among the examiners were those with an intermediate (ovoid) ranking. Statistically significant correlations were found between the ranks of arch shape, arch dimensions, and the polynomial equation analyses. Subjective clinical assessments were generally in agreement at the extremes of tapered and square arch forms; the exceptions were arches with an ovoid shape. There were statistically significant correlations between subjective dental-arch classifications and dental-arch dimensions, as well as the ratio determined from these variables and polynomial equation analyses. Therefore, fourth-order polynomial equations might be an important factor in the quantitative analysis of dental-arch form in orthodontic patients.

Comparison of dental and apical base arch forms in Class II Division 1 and Class I malocclusions

The purpose of this study was to compare the mandibular dental arch form and the mandibular basal bone arch form of patients with Class I malocclusion with those of patients with Class II Division 1 malocclusion. Our aims were to determine differences in dental and basal transverse dimensions and arch forms between the 2 groups, and to determine the usefulness of WALA points as a reference for predicting a stable dental arch form in Class II Division 1 patients. Three-dimensional graphic representations of mandibular casts from 35 Class I malocclusion patients and 32 Class II Division 1 patients were created by using a laser scanning system. Anatomic reference points were subjectively identified and used to represent the dental arch form (FA points) and the arch form of the basal bone (WALA points). The FA point intercanine width was found to be significantly larger in the Class II Division 1 sample compared with the Class I sample, whereas the basal arch form, represented by the WALA ridge, was not significantly different. No significant difference was found in the FA points for intermolar width or in the arch form of the basal bone between the 2 groups. A highly significant correlation between basal and dental arch forms was found at the canine and molar areas in the Class II Division 1 sample, and the FA and WALA point arch forms were highly individual in the Class II Division 1 sample. The mandibular dental arch forms for both the Class I and Class II samples were essentially the same, except at the canines; this is likely due to the nature of the occlusion in Class II Division 1 patients. There was no difference in arch forms of the basal bone between the 2 groups. The use of WALA points or other anatomic landmarks of the basal bone to predict the ideal dental arch form for a patient seems possible and could ensure a more stable orthodontic treatment outcome.

Editor's Comment and Q&A: Comparison of the mandibular dental and basal arch forms in adults and children with Class I and Class II malocclusions

Introduction The mandibular arch form at the levels of both the application point of the orthodontic bracket and the basal bone in adults and children with Class I malocclusion and Class II Division 1 malocclusion was investigated. Methods One hundred thirteen pretreatment mandibular casts were scanned to generate a 3-dimensional computer model of each cast. The casts were divided into Class I and Class II Division 1 malocclusion groups, and were further divided into adults (age, ≥25 years) and children (age, ≤18 years). Two reference points, FA and WALA, were assigned for each tooth. The FA and WALA arch forms were compared, and the distances between corresponding points and intercanine and intermolar widths were analyzed. Results The mandibular intercanine FA point widths were significantly greater in the Class II Division 1 malocclusion group than in the Class I malocclusion group (P <0.05) and were also significantly greater in the Class I adults than in the Class I children (P <0.05). Both the canine FA and WALA point distances and the molar FA and WALA point distances were moderately to highly correlated (R2 >0.55) and highly significant (P <0.001) for all groups. The FA and WALA curves for all groups had individual differences, especially in the premolar and molar areas. Conclusions The Class II Division 1 mandible is essentially the same as the Class I mandible with respect to basal bone and dental arch dimensions. WALA points can be used to predict individual dental arch forms in adults and children. Dental and basal arch forms were not significantly different between adolescents and adults. The mandibular arch form at the levels of both the application point of the orthodontic bracket and the basal bone in adults and children with Class I malocclusion and Class II Division 1 malocclusion was investigated. One hundred thirteen pretreatment mandibular casts were scanned to generate a 3-dimensional computer model of each cast. The casts were divided into Class I and Class II Division 1 malocclusion groups, and were further divided into adults (age, ≥25 years) and children (age, ≤18 years). Two reference points, FA and WALA, were assigned for each tooth. The FA and WALA arch forms were compared, and the distances between corresponding points and intercanine and intermolar widths were analyzed. The mandibular intercanine FA point widths were significantly greater in the Class II Division 1 malocclusion group than in the Class I malocclusion group (P <0.05) and were also significantly greater in the Class I adults than in the Class I children (P <0.05). Both the canine FA and WALA point distances and the molar FA and WALA point distances were moderately to highly correlated (R2 >0.55) and highly significant (P <0.001) for all groups. The FA and WALA curves for all groups had individual differences, especially in the premolar and molar areas. The Class II Division 1 mandible is essentially the same as the Class I mandible with respect to basal bone and dental arch dimensions. WALA points can be used to predict individual dental arch forms in adults and children. Dental and basal arch forms were not significantly different between adolescents and adults.

Comparison of the mandibular dental and basal arch forms in adults and children with Class I and Class II malocclusions

The mandibular arch form at the levels of both the application point of the orthodontic bracket and the basal bone in adults and children with Class I malocclusion and Class II Division 1 malocclusion was investigated. One hundred thirteen pretreatment mandibular casts were scanned to generate a 3-dimensional computer model of each cast. The casts were divided into Class I and Class II Division 1 malocclusion groups, and were further divided into adults (age, > or =25 years) and children (age, < or =18 years). Two reference points, FA and WALA, were assigned for each tooth. The FA and WALA arch forms were compared, and the distances between corresponding points and intercanine and intermolar widths were analyzed. The mandibular intercanine FA point widths were significantly greater in the Class II Division 1 malocclusion group than in the Class I malocclusion group (P <0.05) and were also significantly greater in the Class I adults than in the Class I children (P <0.05). Both the canine FA and WALA point distances and the molar FA and WALA point distances were moderately to highly correlated (R(2) >0.55) and highly significant (P <0.001) for all groups. The FA and WALA curves for all groups had individual differences, especially in the premolar and molar areas. The Class II Division 1 mandible is essentially the same as the Class I mandible with respect to basal bone and dental arch dimensions. WALA points can be used to predict individual dental arch forms in adults and children. Dental and basal arch forms were not significantly different between adolescents and adults.

Comparison of maxillary and mandibular dental arch forms by studying Fourier series developed from mathematically estimated dentitions

We conducted a Fourier analysis on data obtained using correlation and principal component analyses of parallel-standardized dental study models; both maxillary and mandibular dental arches were predominantly round square in shape. The present study compared and determined the contribution ratio and reproducible coefficients of amplitudes (factors affecting dental arch forms), and demonstrated that the 1st to 4th and the 1st to 6th Fourier harmonics reproduced maxillary and mandibular dental arch forms, respectively. The correlation analyses of the constant term and amplitudes demonstrated that significant differences in the 2nd harmonic amplitude was strongly correlated with the curvature of anterior teeth and the length-to-width ratio in maxillary dentitions. By comparison of the constant term and amplitudes between different arch types, we did not observe significant differences in the constant term and the 1st amplitude of maxillary dentitions and in constant term and all amplitudes of mandibular dentitions. Nevertheless, the study revealed high contribution ratios of the 1st (in mandibular dentitions) and the 2nd (in maxillary dentitions) amplitudes essentially affecting the reproducibility of arch forms. The 1st amplitudes demonstrated a bow-like arrangement of all arch types, while the 2nd amplitudes adjusted the anterior-teeth curvature and in particular demonstrated the length-to-width ratio of maxillary dentitions. The 3rd and the 4th amplitudes were also determinants of the anterior-teeth curvature of maxillary dentitions. The 6th amplitude was necessary for reproduction, but showed no difference between varying mandibular dental arch types. Collectively, we conclude that the establishment of a Fourier series significantly reproduced maxillary but not mandibular dental arch forms.