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

Stefano Sivolella,Amalia Lupi,Francesco Cavallin,Nadia Ferrarese,Chiara Giraudo,Silvia Meggiorin,Antonino Fiorino

doi:10.1038/s41598-020-73180-3

Stefano Sivolella, Amalia Lupi + Show 5 more

Open Access

https://doi.org/10.1038/s41598-020-73180-3

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Abstract

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.

Highlights

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants
Model selection in the multilevel multivariable analysis of the bone widths (BWs) was performed by minimizing the Akaike information criterion (AIC): the 3-way interaction term was removed
In the final model (Table 3), BW was associated with site (p < 0.0001) and depth of measurement (p < 0.0001)

Summary

Introduction

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. The position and morphology of the inferior alveolar canal, and the dimension of the alveolar bone have been studied both in two-dimensional radiography and three-dimensional computed tomography It has proved useful for examining whether a correlation exists between these measurements and other variables, such as sex and age[1,2,3,4,5,6,7]. Analyzing the dimensions of the alveolar ridge in young dentulous patients helped to shed light on the bone remodeling process, to predict the need for any bone grafting, and to orient the choice of the most appropriate size of implant Such dimensional assessments facilitated the prosthetic rehabilitation of edentulous patients. Standard length implants placed in vertically regenerated posterior mandibular sites has been compared to short and extra short implants in the severely resorbed mandible, in terms of implant and prosthetic survival, marginal bone resorption and morbidity[13,14,15,16,17,18]

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