The aim of this in vitro study was to evaluate, using the photoelastic analysis method, the stress distribution in mandibular bone surrounding a bar-clip overdenture when 2 implant angulations were simulated. Two mandibular photoelastic models were manufactured, with 2 implants embedded in the interforaminal region: model 1 - PAPI, a photoelastic analysis model with parallel implants; and model 2 - PAAI, a photoelastic analysis model with angled implants. A bar-clip retention system and an overdenture were positioned over the implants, and loads of 1.0, 2.0 and 3.0 bars were applied. The resultant stresses that developed in the supporting structure were photoelastically monitored and were recorded photographically. The results showed that there were no similarities in the areas of stress among the photoelastic resin models when the angulation of the implants was evaluated. Model 1 - PAPI presented a higher stress concentration at the implant apex, while in model 2 - PAAI, there were higher stress concentrations on the mesial and distal implant faces. Within the limitations of this study, it was concluded that the PAPI photoelastic model demonstrated better stress transfer compared to the PAAI model, since the forces oriented along the axis were better absorbed by the bone.

O objetivo deste estudo foi avaliar se a introdução de um dispositivo resultante da combinação de um encaixe o'ring a um ortoimplante (o'ring ortho implant) nas guias da técnica de cirurgia guiada convencional, contribui para minimizar os desvios da posição e inclinação de implantes, no momento da sua colocação. Foram confeccionados 10 modelos simulando tecido ósseo, divididos aleatoriamente em 2 grupos: 5 com a guia tomográfica e cirúrgica da técnica usual, representando o grupo controle (C), e 5 com as guias fixadas a o'ring ortho implants, representando o grupo experimental (T). Quarenta implantes de 4 × 11 mm foram instalados nos grupos, usando as respectivas guias tomográficas e cirúrgicas. A avaliação dos resultados foi realizada pela sobreposição dos planejamentos virtuais, derivados de tomografias computadorizadas précirúrgicas, com as realizadas após a colocação dos implantes. Não houve diferenças estatisticamente significantes para os desvios angulares (Teste Tukey F = 1,06 e p = 0, 3124) e lineares (Teste ANOVA F = 2,54 e p = 0,11). No entanto, os valores angulares do grupo T mostraram menor desvio padrão em relação aos do grupo C. O uso de o'ring ortho implants pode minimizar as alterações de posicionamento dos implantes no momento da sua colocação, beneficiando a técnica da cirurgia virtual guiada usual.

The aim of this study was to evaluate whether the introduction of a device, resulting from the combination of an o'ring attachment with an orthodontic implant (o'ring ortho implant, O'ROI), to affix the surgical template of CAD/CAM-guided implant surgery contribute to minimizing the deviations in the position and inclination of implants at the time of their placement. Ten models simulating bone tissue were fabricated and randomly divided into 2 groups: 5 with the scanning and surgical template of the usual technique, representing the Control Group (C), and 5 with scanning and surgical templates fixed by o'ring ortho implants (O'ROI), representing the Test Group (T). Forty implants measuring 4×11 mm were placed in the groups, using the respective templates. The results were evaluated by the fusion of CT images of the planned and placed implants. The locations and axes were compared. There were no statistically significant differences for the angular (Tukey's test F = 1.06 and p = 0. 3124) and linear (ANOVA F = 2.54 and p = 0.11) deviations. However, the angular values of Group T showed a lower standard deviation in comparison with those of Group C. The use of o'ring ortho implants (O'ROI) is able to minimize the angular and linear deviation of implants at the time of their placement.