Archform Comparisons between Skeletal Class II and III Malocclusions

Abstract

The purpose of this cross-sectional research was to explore the relationship of the mandibular dental and basal bone archforms between severe Skeletal Class II (SC2) and Skeletal Class III (SC3) malocclusions. We also compared intercanine and intermolar widths in these two malocclusion types. Thirty-three virtual pretreatment mandibular models (Skeletal Class III group) and Thirty-five Skeletal Class II group pretreatment models were created with a laser scanning system. FA (the midpoint of the facial axis of the clinical crown)and WALA points (the most prominent point on the soft-tissue ridge)were employed to produce dental and basal bone archforms, respectively. Gained scatter diagrams of the samples were processed by nonlinear regression analysis via SPSS 17.0. The mandibular dental and basal bone intercanine and intermolar widths were significantly greater in the Skeletal Class III group compared to the Skeletal Class II group. In both groups, a moderate correlation existed between dental and basal bone arch widths in the canine region, and a high correlation existed between dental and basal bone arch widths in the molar region. The coefficient of correlation of the Skeletal Class III group was greater than the Skeletal Class II group. Fourth degree, even order power functions were used as best-fit functions to fit the scatter plots. The radius of curvature was larger in Skeletal Class III malocclusions compared to Skeletal Class II malocclusions (rWALA3>rWALA2>rFA3>rFA2). In conclusion, mandibular dental and basal intercanine and intermolar widths were significantly different between the two groups. Compared with Skeletal Class II subjects, the mandibular archform was more flat for Skeletal Class III subjects.

A secondary analysis to determine variations of dental arch measurements with age and gender among Ugandans

“…From literature, it has been observed that significant changes in dental arch dimensions are associated with development of the permanent dentition from the age of 6 years (first molar) to 12 years (second molar) and finally 18 years (third molar) [ 9 – 12 ]. It is also important to note that the dental arch dimensions will also tend to differ between different participants of Angles classification [ 22 , 23 ], this is an additional source of variation that must be taken care of in such a study. So in this study, while we only included participants of Angles class I, it is possible that we may have missed the majority of changes in dental arch dimensions given our older study population, older than the mixed dentition.…”

Distances between mandibular posterior teeth and the WALA ridge in Peruvians with normal occlusion

“…This diversity has led some authors to recommend specific concepts for customizing the shape of dental arches for patients in order to improve the prospects of post-treatment stability, health, function, and appearance. 4 - 7 …”

“… 1 - 3 Because of the wide variety in dental arch forms between individuals, it is important to seek universal points of reference that could establish a guideline for individualizing arch forms for patients seeking orthodontic treatment. 2 , 4 It has been suggested to use the buccal aspect of mandibular alveolar bone, known as the WALA ridge, as such a reference. The WALA ridge is clinically identifiable as a soft-tissue band immediately superior to the mucogingival junction.…”

Morphometric analysis of the maxillary root apex positions according to crowding severity

“…1 Until now, most research on the dental arch form has concerned arch form at the level of the crowns of the teeth (crown arch form) or basal bone arch form; studies on the root apex arch form have been very rare. [2][3][4][5] Recent progress in conebeam computed tomography (CBCT) has made root apex studies possible in living individuals. 6 The research considering crown arch forms includes the use of facial axis points (FA); the research considering the basal bone arch form includes the use of mucogingival junction points or root centre points.…”

“…6 The research considering crown arch forms includes the use of facial axis points (FA); the research considering the basal bone arch form includes the use of mucogingival junction points or root centre points. [2][3][4][5] However, the arch form constructed from these points is measured from two-dimensional models. As the positions of root apices are three-dimensional, root apex points should be measured three-dimensionally and projected onto the reference plane (eg, palatal plane, occlusal plane) to construct the arch form accurately.…”