Twist removal of healed vs. nonhealed implants-a mechanical and histological study in mini pigs.

Ricardo de Oliveira Silva,Paulo Henrique Ferreira Caria,Fabrício Passador

doi:10.1186/s40729-016-0059-x

Ricardo de Oliveira Silva, Paulo Henrique Ferreira Caria

Open Access

https://doi.org/10.1186/s40729-016-0059-x

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Abstract

PurposeThe objective of this study was to evaluate the effect of removal torque (reverse torque) of titanium implants in peri-implant bone.MethodsThe P1-M1 teeth were extracted bilaterally of 6 mini pigs (BR-1). Each animal received 6 titanium implants, three for each side of mandible. On the right side of mandible, 3 implants reminded 9 months (9M) under masticatory activity and on the left side, other 3 implants were placed and immediately removed (IR). All 36 implants were removed by removal torque, and the recorded values were statistically analyzed. Animals were euthanized right after the removal torque and recording. Each third (cervical, medium, and apical) of peri-implant bone was extracted and analyzed histological and immunohistochemically. Student’s t test was used to determine statistical differences in the values between the 9M and IR samples. Data were presented as means with standard deviations. The level of significance was set at 5% (P < 0.05).ResultsRemoval torque was higher in 9M experimental situation than in IR. Histological characteristics of mature bone were presented in the 9M experimental condition, and immature bone characteristics were presented in the IR experimental condition. Removal torque caused small fractures and rounding in the bone grooving. Immunohistochemical analysis reinforced the histological results; Student’s t test provided statistically significant differences to osteocalcin expression in 9M samples and no statistically significant differences expression to collagen I in both experimental conditions (P < 0.05).ConclusionsRemoval torque caused microscopical fractures and smoothing in the peri-implant bone grooves, but it does not compromise the bone healing.

Highlights

Since the discovery of osseointegration by Branemark in Sweden in 1960, where found that when titanium screws left undisturbed in bone, the osteocytes grow in close apposition to the titanium surfaces and provide firm anchorage
This study evaluated the peri-implant bone after his immediate removal and after 9 months of osseointegration
There was no difference in the healing between animals who had the implants immediately removed after installation, and animal whose implants were removed 9 months later of installation

Summary

Introduction

Since the discovery of osseointegration by Branemark in Sweden in 1960, where found that when titanium screws left undisturbed in bone, the osteocytes grow in close apposition to the titanium surfaces and provide firm anchorage. This discovery was successfully applied in dental and craniofacial reconstructive surgery in 1965 [1, 2]. The incorrect position of implants can cause maxillary sinus membrane damage, pressure on the dental nerves, or difficulties in prosthetic procedure as well as inconvenient esthetical problems. Esthetical requirements of patients have increased, especially for anterior teeth [12, 13].

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