Fixture Length and Primary Stability: An In Vitro Study on Polyurethane Foam

Morena Petrini,Margherita Tumedei,Maria Stella Di Carmine,Giovanna Iezzi,Alessandro Cipollina,Simonetta D’Ercole,Marco Re,Adriano Piattelli

doi:10.3390/app12052683

Abstract

(1) Background: Recently, novel dental implants that are characterized by different levels of surface roughness in the distinct parts of the fixture’s body have been introduced in the market. These surface characteristics could affect the primary stability of the implants. The aim of this in vitro study was to compare the primary stability of short and long implants, characterized by multiscale surface roughness, inserted on polyurethane blocks. The secondary aim was to understand if the implant length could be a crucial factor in the decision-making in immediate or rather than delayed loading protocol in the different bone densities. (2) Methods: A total of 20 cylindrical dental implants with a diameter of 5.0 mm were tested for the lengths 6.0 mm (short implants) versus 13.0 mm (long implants) on two different solid rigid polyurethane blocks (20 and 30 PCF). The primary stability was evaluated by measuring the insertion torque value (ITV), the removal torque (RTV), and the resonance frequency analysis RFA. (3) Results: The values of ITV, RTV, and RFA showed the same trend in all measurements. Long implants showed a significantly higher primary stability on 30 PCF blocks that present mechanical properties similar to high-density bone. On the contrary, no relevant differences were found on 20 PCF blocks, which mimic trabecular bone density. (4) Conclusions: The impact of fixture length on the primary stability of implants with multiscale surface roughness is significant in 30 PCF polyurethane corresponding to higher bone density, but not in lower ones.

Highlights

The achievement of primary stability during the dental-implant insertion is the first step toward a successful osseointegration [1]
The primary stability was evaluated by measuring the insertion torque value (ITV), the removal torque (RTV), and the resonance frequency analysis Resonance frequency analysis (RFA). (3) Results: The values of ITV, removal torque value (RTV), and RFA showed the same trend in all measurements
We have shown that multiscale-roughness dental implants of 3.0 and 5.0 diameters showed high insertion torque and primary stability on polyurethane blocks, and this is valuable for implant-loading protocols [28]

Summary

Introduction

The achievement of primary stability during the dental-implant insertion is the first step toward a successful osseointegration [1]. A good glycemic control is fundamental to reduce implant failures in the first stages of healing [4]. Evidence supports the adoption of the second-stage protocol, with submersed implants during the healing stage, if primary stability is low [5]. Other authors suggest to solidarize the implants by means of metallic bars or intraoral electric welders in order to proceed directly to an immediate loading protocol (ILP) [5,6]. The adoption of ILP of dental implants needs the presence of primary stability [7]. The literature suggests that, for ILP of full-arch restorations, the achievement of an insertion torque value (ITV) > 30 Ncm is necessary in order to avoid early failures [8,9]. With the advent of novel implant surfaces, this value can further be reduced

Results

Discussion

Conclusion