Mandibular Geometry Research Articles

Morphometric analyses of the mandible in prepubertal craniofacial microsomia patients treated with an inverted-L osteotomy.

To analyze changes in mandibular form associated with an inverted-L osteotomy and autogenous bone graft, preoperative, early postoperative (EPO), and late postoperative (LPO) lateral cephalographs of 14 children (mean age approximately 9 years) with unilateral craniofacial microsomia (CFM) were scanned and nine mandibular landmarks digitized. Average mandibular geometries, scaled to an equivalent size, were generated using Procrustes superimposition. Cephalometry, Euclidean distance matrix analysis (EDMA), and thin-plate spline (TPS) analyses were carried out on mean mandibular configurations. Cephalometric results showed increases in oblique mandibular length (approximately 9% on average, P < 0.05) and increased ramus height (P < 0.05). Similarly, using EDMA there were also significant differences (P < 0.05) between the mean preoperative, EPO, and LPO configurations. The most demonstrable EPO change in the mandibular configuration using EDMA was increased oblique length (approximately 11%). This improvement depended on ramus oblique lengths increasing by approximately 26%, ramus height increasing by approximately 25%, and mandibular body length increasing by approximately 5%. For TPS analysis, affine and nonaffine changes contributed to the total spline. In all three comparisons the affine transformation showed an antero-inferior rotation of the mandibular configuration. For nonaffine changes the EPO configuration indicated a supero-inferior stretch of the mandibular configuration. The nonaffine LPO changes maintained the supero-inferior stretch of the mandibular configuration. It is concluded that improvements in the lateral facial profile of CFM patients can be achieved using an inverted-L osteotomy, with little relapse approximately 2 years postoperatively.

Euclidean distance matrix analysis of surgical changes in prepubertal craniofacial microsomia patients treated with an inverted L osteotomy.

Correction of craniofacial microsomia (CFM) presents several challenges concerning the modality of surgical intervention. The aim of this study was to assess early and late surgical outcome, by undertaking Euclidean distance matrix analysis (EDMA) of CFM patients exhibiting an unilateral mandibular deformity that was surgically corrected by an inverted L osteotomy and autogenous bone graft. Longitudinal study. Preoperative, approximately =1-year postoperative and approximately 3-year postoperative assessments of 14 consecutive children (mean age 9 years) with CFM. Posteroanterior cephalographs were scanned and five homologous mandibular landmarks were digitized in triplicate (< 1% digitization error). Average mandibular geometries, scaled to an equivalent size, were generated using a generalized rotational fit program (Procrustes superimposition) and subjected to EDMA. The mean pre- and both postoperative mandibular configurations differed statistically (p < .01). Early postoperative improvements in mandibular form were noted; increases in length arising in the treated mandibular body (approximately =19%) and ramus (approximately =13%). Comparing early and late postoperative configurations, a decrease of approximately =22% in the late postoperative mandibular body length was evident, but the ramus maintained steady vertical growth (approximately =7%). Comparing the preoperative and late postoperative configurations, the decrease observed in the mandibular body on the treated side was reduced to approximately =8% while the ramus maintained good growth (approximately =20%) on that side. Mandibular morphology is improved significantly in CFM patients surgically treated by an inverted L osteotomy, but relapse in the mandibular body is evident after approximately =3 years. Nevertheless, ramus growth proceeds well after the surgical reconstruction.

Euclidean Distance Matrix Analysis of Surgical Changes in Prepubertal Craniofacial Microsomia Patients Treated With an Inverted L Osteotomy

Abstract Objectives: Correction of craniofacial microsomia (CFM) presents several challenges concerning the modality of surgical intervention. The aim of this study was to assess early and late surgical outcome, by undertaking Euclidean distance matrix analysis (EDMA) of CFM patients exhibiting an unilateral mandibular deformity that was surgically corrected by an inverted L osteotomy and autogenous bone graft. Design: Longitudinal study. Preoperative, ≈1-year postoperative and ≈3-year postoperative assessments of 14 consecutive children (mean age 9 years) with CFM. Posteroanterior cephalographs were scanned and five homologous mandibular landmarks were digitized in triplicate (< 1% digitization error). Average mandibular geometries, scaled to an equivalent size, were generated using a generalized rotational fit program (Procrustes superimposition) and subjected to EDMA. Results: The mean pre- and both postoperative mandibular configurations differed statistically (p < .01). Early postoperative improvemen...

Procrustes, Euclidean and cephalometric analyses of the morphology of the mandible in human Class III malocclusions

The role of mandibular phenotype in the development of Class III malocclusion remains unclear. The purpose of this study was to determine whether the form of the mandible differed between prepubertal individuals with Class I and Class III malocclusions. Lateral cephalographs of 73 children of European-American descent aged between 5–11 years with Class III malocclusion were compared to those of 60 counterparts with a normal, Class I molar occlusion. The cephalographs were traced and checked, and eight homologous mandibular landmarks were digitized. Average mandibular geometries, scaled to an equivalent size, were generated using Procrustes superimposition. Euclidean distance matrix analysis (EDMA) was undertaken to corroborate the Procrustes analysis, and bivariate analysis utilizing eight linear and five angular measurements was also performed. Residuals and F-values from Procrustes analysis indicated that mandibular configurations differed statistically for Class I and Class III types. EDMA confirmed that the Class I and Class III geometries were significantly different, revealing that the greatest differences in morphology arose in the anterior-most mandibular regions. As well, most variables showed statistically significant differences when the Class I and Class III mandibular types were compared. When the sample was subdivided into seven age- and sex-matched groups, nearly all age-based comparisons were significantly different. It is concluded that the morphology of the mandible differs in individuals with Class III malocclusions when compared to the normal Class I configuration, and that these alterations may indicate dichotomous postnatal mandibular ontogeny.

Individual augmentation of the atrophic mandible based on CAD/CAM-manipulated computed tomography data — in vitro results

The problems of shaping a stable alveolar ridge form favorable for prosthodontic treatment by the various methods of ridge augmentation raise the question of whether computer-aided design (CAD) may be used for geometric modeling of the implant. Helical computed tomography (CT) data were used to create a three-dimensional (3-D) model of the atrophic mandible. This numerically based model served as the basis for a free-form-surface design of the implant's form, height, and position. The idealized data required for this geometric modeling were also derived from numerically based serial sections of 104 mandibles of dried skulls. The modeling procedure followed the formula “idealized mandibular geometry minus patient's geometry”, yielding the geometric data of the implant. These numerically control (NC) a milling machine to fabricate the individual implant. The augmentation of an atrophic mandible of a dried skull is presented as the first in vitro trial of this new method.