Louis Matthew Andria | PubMed Health

PubMed2007

Mandibular first molar relation to variable lower face skeletal components.

OBJECTIVE: To evaluate the position of the mandibular first permanent molar in the mandible relative to several factors. MATERIALS AND METHODS: A total of 185 untreated Class I and Class II patients were randomly selected from a sample of 350 patients from a single office. The palatal and mandibular planes were related to Frankfort horizontal to create the interjaw or "B" angle. Age and the mesial contact of the mandibular first molars were used. The landmarks were projected at right angles to the Frankfort horizontal for effective mandibular dimension lengths. Actual-length dimensions were projected at right angles to the mandibular plane. Pearson product moment correlation coefficients were computed to evaluate the effect of age, cranial length, and mandibular contribution to the molar's sagittal position in the mandible. Significance was reported only when P < .05 to determine a 95% confidence level. RESULTS: Statistically significant positive correlations indicated that the mandibular molar is located more forward with increasing age, longer mandibular body length, and increasing posterior facial height. In contrast, significant negative correlations to the interjaw, mandibular plane, ramal inclination angles, and the linear ramal contribution corresponded to a more posterior position of the molar with increasing angles. CONCLUSIONS: The mandibular first permanent molar is located more anteriorly with an older patient, a longer mandibular body, greater posterior facial height, and an acute interjaw angle. In contrast, an increase in the forward tip of the ramus places the molar in a more posterior location.

Age Factors↗

PubMed2002

Comparative long term post-treatment changes in hyperdivergent Class II Division 1 patients with early cervical traction treatment.

This was a retrospective study of 45 Class II Division I hyperdivergent patients treated in the mixed dentition with cervical traction and an incisor biteplane. The interjaw or "B" angle (mandibular plane to palatal plane angle) was used to determine hyperdivergency. The treated sample was subdivided into 2 groups reflecting whether the mandibular or palatal plane contributed the greatest amount to the more than 1 standard deviation of the "B" angle from the mean value of the "B" angle present in the 89 untreated Class I controls. Complete records including lateral cephalometric head films were acquired at the start of treatment and 18 to 91 months after discontinuing all retention. Null hypotheses were designed to determine if any significant changes in the "B" angle, mandibular plane angle, or palatal plane angle occurred in the control group or the treated group. Thirty-two angular, linear, and proportional data were accumulated to determine the presence or absence of significant differences. The only significant angular differences found were in the group in which the palatal plane inclination was increased relative to Frankfort Horizontal. In this group, the palatal plane became more nearly parallel to Frankfort Horizontal than in the control group, and showed an increase instead of a decrease in the Y-axis. Proportional and linear data indicated the palatal plane change was a lack of descent of Posterior Nasal Spine while the descent of Anterior Nasal Spine was equal to that of the control group. The increase in the Y-axis was not the result of bite opening, but a lack of mandibular horizontal development as indicated by less of an increase in the Facial Angle. Of the 45 patients, only 4 (9%) required 2 phases of treatment and 1 of those required extraction. Thirty patients (67%) completed treatment with alignment and retraction of the maxillary anterior segment and 11 (24%) had additional alignment of the mandibular anterior segment.

Analysis of Variance↗