The relationship between facial morphology and the structure of the alveolar part of the mandible in edentulous complete denture wearers. A preliminary study

Sexual dimorphism of the mandibular conformational changes in aging human adults: A multislice computed tomographic study by geometric morphometrics

The aging process has an impact on mandibular bone morphology and can therefore affect shape sexual dimorphism. Understanding the effect of senescence on mandibular shape changes is particularly important to correctly estimate the sex of an individual and predict age-related conformational modifications. The purpose of this study was to assess age-related changes in mandibular shape and sexual dimorphism. The study sample comprised 160 Multi Slice Computed Tomography examinations of individuals aged 40 to 79 years. Geometric morphometric analysis of fourteen osteometric landmarks was used to examine sexual dimorphism and patterns of mandibular shape variation with age. Results showed that mandibular sexual dimorphism of shape remained significant with aging. Conformational changes occurred between 50 and 70 years and were different for male and female individuals. Females presented earlier and more marked age-related shape changes than males. These observations suggest that mandibular senescence is a sexually dimorphic process since its onset, rate, and the areas subjected to conformational changes differ from male to female individuals. Senescence-related changes present substantial variability, and further investigation is required to determine precisely the age that marks their onset.

CT-based dentulous mandibular alveolar ridge measurements as predictors of crown-to-implant ratio for short and extra short dental implants

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. Hence, vertical and horizontal dimensions of dentulous posterior mandibles in a sample of 18- to 25-year-olds were measured, and correlations of these dimensions with sex and site were investigated. Mandibular computed tomography scans from 100 subjects were considered. Vertical and horizontal bone and tooth measurements were taken at the sites of the second premolar (PM), and the mesial and distal roots of the first and second molars (M1m, M1d, M2m and M2d, respectively). A hypothetical crown-to-implant ratio (C/I R) was calculated assuming the insertion of short and extra short implants (5, 6 or 7 mm), at 1.5 mm from the inferior alveolar canal, maintaining the position of the existing occlusal plane. All vertical bone dimensions decreased from the PM to the M2d. Width measurements increased from the mesial (PM) to the distal sites (M1m, M1d, M2m and M2d). Males had significantly greater vertical and horizontal measurements than females at all sites. The mean C/I R was higher than 2 for all sizes of implant. The C/I R was lower for the second molar than for the second premolar, while it was similar for the first molar and the second premolar. Males had a higher C/I R than females. Computed tomography can be used to study the anatomical features of alveolar bone, and to predict some clinical aspects of prosthetic rehabilitation with implants, such as the crown-to-implant ratio in conditions of serious bone atrophy.

Alveolar ridge atrophy related to facial morphology in edentulous patients

OBJECTIVES

The morphology of the alveolar process determines the retention and stability of prosthetic restorations, thereby determining the result of the therapy. Considering that the edentulous jaws may be affected by the atrophy process, it was hypothesized that the morphology of the alveolar process of the maxilla may be dependent on the anterior facial height and anatomy of the mandible.

SUBJECTS AND METHODS

Twenty-five healthy edentulous Caucasian individuals were randomly chosen. Each subject underwent a lateral cephalogram before and after prosthetic rehabilitation. During exposition, newly made prostheses were placed in the patient's mouth. Teeth remained in maximal intercuspidation. Morphological parameters were evaluated according to the Ricketts, McNamara, and Tallgren's method.

RESULTS

An inversely proportional association was observed between patient age and the distal part of the maxilla. A statistically significant connection was noted between the vertical dimension of alveolar ridge and anterior total and lower facial height conditioned by prosthetic rehabilitation.

CONCLUSION

The height of the lateral part of the alveolar ridge of the maxilla remains in connection with the anterior total and lower facial height obtained in the course of prosthetic rehabilitation. The vertical dimension of the alveolar ridge of the maxilla seems to be in close relationship with the morphology of the lower jaw.