Anterior occlusion in shortened dental arches

Objectives The aim of this study was to examine the occlusion of anterior teeth in individuals with shortened dental arch (SDA). Material and methods In a case–control clinical study, 41 individuals with SDA and 41 individuals with complete dental arch (CDA) participated. The CDA control group was matched for age and gender. Testing for occlusal contacts of anterior maxillary teeth was conducted by biting on foil strips (8 µm) with subjectively normal bite force (NBF) and maximal bite force (MBF). The data was analyzed on individual and tooth levels. Results The median rates of anterior maxillary teeth with occlusal contacts were 0.67 (NBF) and 0.83 (MBF) in the SDA group and 0.50 (NBF) and 0.83 (MBF) in the CDA group. Within both groups, the contact rates were significantly higher in MBF. The group difference with NBF was significant. A generalized linear model showed that the odds of an anterior maxillary tooth to have an occlusal contact were greater in the SDA both for NBF with an odds ratio (OR) 2.277 and MBF with an OR 1.691. Conclusions The findings suggest effective compensatory mechanisms relative to the occlusal function in individuals with SDA. Clinical relevance The study delivers further evidence regarding the SDA concept as a viable option in the management of posterior tooth loss.

Stress and strain distribution in the lower jaw with shortened dental arch - a finite element method study

Introduction/Objective. The absence of functional loading due to molar loss might cause changes to the microstructure of the bone. Therefore we investigated and visualized deformation and strain pattern distribution of the mandibule with full arch dentition (FDA) and shortened dental arches (SDA) during occlusion. Methods. A 3D model of an adult cadaveric dentate mandible, without pathological and traumatic damages, was developed based on CT scan images, set to 0.7 mm slice thickness. The scanned slices were imported into software where the bone and teeth were identified and modelled separately based on image density thresholding. Using the software and based on the grey-scale analysis of the slices initial meshes for the cortical, cancellous bone and teeth were generated. Results. Highest stress/strain values were registered in the structures adjacent to molars i.e. molar region of processus alveolaris assigned by blue color in FDA model. Similar to FDA, the SDA models exibited deformation with evident highest strain (9.33%) at the processus coronoideus and mandibular angle. ?he highest overall stress (5 MPa) and strain (6.67%) was found in the mandibular intercanine segment of the SDA model, considering the mandibular body. Conclusion. Finite element method can be employed as a powerfull tool for visualization of the stress and strain of the loaded mandible models with full and shortened dental arches. It was registered that molar support loss caused higher stress and strain in SDAs compared to FDA model.