Effect of bone loss simulation and dental-splinting on bone strain

Objective: to analyze the effect of support bone loss and dental splinting type on strain measured of the anterior mandibular bone replicas.

Methods: 80 human mandibular teeth (20 central incisors, 20 lateral incisors, 20 canines and 20 premolars; being half of right side and half of left side) were selected and randomly divided in 10 groups with 8 teeth in each. For strain-gauge test, 10 polystyrene resin mandibular replicas with teeth embedded, simulating periodontal ligament with polyether impression material, were made. Four strain-gauges were fixed on buccal and lingual surfaces on central and lateral incisor regions. Each replica (n=10) was tested in 7 experimental situations: Cont, control group, no bone support alterations without splinting; Bl, simulating 5mm of bone loss (Bl) between canines teeth; BlCr, Bl associated with splinting between canines teeth with composite resin (Cr) only; BlW, Bl and splinting with 0.25mm wire ligature(W) only; BlWCr, Bl and splinting made with association between W and Cr; BlFgCrExt, Bl and extra-coronal splinting made with association between fiber glass and Cr; BlFgCrInt, Bl with intra-coronal splinting made with association between fiber glass and Cr. The strain values were assessed under 150N oblique load applied over anterior teeth in a universal testing machine. Data were analyzed by 3-way ANOVA and Scheffe test (p<0.05). Results: strain on buccal surface was higher than on lingual surface. Strain measured on central incisor region was higher than on lateral incisor region. Splinting types showed similar behavior for all surfaces and regions tested. The strain values (µS) on central incisor region-buccal surface were: BlFgCrInt-554.9±152.4^a; BlFgCrExt- 556.3±150.4^a Cont-561.1±191.0^a; BlWCr- 602.3±125.4^ab; BlCr-607.7±149.2^ab; BlW- 706.0±137.4^bc;Bl- 866.9±209.8^c.

Conclusions: The dental support loss increased the strain values. The W-splinting no reduced the strain values. Dental splinting made with Cr produced significantly decrease on strain measured on dental support.