Effect of crown to implant ratio and implantoplasty on the fracture resistance of narrow dental implants with marginal bone loss: an in vitro study

Abstract

Background Peri-implantitis is a biological complication that affects soft and hard tissues around dental implants. Implantoplasty (IP) polishes the exposed implant surface, to decontaminate it and make it less prone to bacterial colonization. This study investigates whether a higher clinical crown-to-implant-ratio (CIR) reduces implant fracture resistance and whether implants are more fracture-prone after IP in the presence of 50% of bone loss. Methods Forty-eight narrow platform (3.5 mm) 15 mm long titanium dental implants with a rough surface and hexagonal external connection were placed in standardized bone-like resin casts leaving 7.5 mm exposed. Half were selected for IP. The IP and control groups were each divided into 3 subgroups with different clinical CIRs (2:1, 2.5:1 and 3:1). The implant wall width measurements were calculated using the software ImageJ v.1.51 through the analysis of plain x-ray examination of all the samples using standardized mounts. A fracture test was performed and scanning electron microscopy was used to evaluate maximum compression force (Fmax) and implant fractures. Results IP significantly reduced the implant wall width (P < 0.001) in all reference points of each subgroup. Fmax was significantly higher in the 2:1 subgroup (control = 1276.16 N ± 169.75; IP = 1211.70 N ± 281.64) compared with the 2.5:1 (control = 815.22 N ± 185.58, P < 0.001; IP = 621.68 N ± 186.28, P < 0.001) and the 3:1 subgroup (control = 606.55 N ± 111.48, P < 0.001; IP = 465.95 N ± 68.57, P < 0.001). Only the 2.5:1 subgroup showed a significant reduction (P = 0.037) of the Fmax between the controls and the IP implants. Most fractures were located in the platform area. Only 5 implants with IP of the 2:1 CIR subgroup had a different fracture location (4 fractures in the implant body and 1 in the prosthetic screw). Conclusions IP significantly reduces the fracture resistance of implants with a 2.5:1 CIR. The results also suggest that the CIR seems to be a more relevant variable when considering the resistance to fracture of implants, since significant reductions were observed when unfavorable CIR subgroups (2.5:1 and 3:1 CIR) were compared with the 2:1 CIR samples.

Influence of marginal bone resorption on two mini implant-retained mandibular overdenture: An in vitro study

“…It seems that MIs with MBR near the loading side may potentially be more prone to suffer from overloading than other implants. Leitão-Almeida et al 26 performed an in vitro study with narrow implants (3.5 mm) in a situation of 50% bone loss, which was similar to the resorption group in the present study. They concluded that increasing the clinical crown height significantly reduced the implant resistance to loading, and further led to the probability of fatigue fracture increased.…”

“… 20 24 The focus of this in vitro study was to investigate the biomechanical effect of MBR on the strain of the MI and the support of the MI-OD. In view of the acceptable bone loss 15 17 and pathological bone loss, combining with the previous studies conducted by Linetskiy et al 25 (assumed implants in 10+ years of service with 0.2 mm annual bone loss) and Leitão-Almeida et al 26 (simulated narrow implants in 50% height of bone loss), the resorption group in the present study was simulated in the situation of MI with bone loss to 1/2 length to provide information especially for extreme bone loss cases. The location and direction of the strain gauge was also a crucial factor.…”

Effect of bone loss on the fracture resistance of narrow dental implants after implantoplasty. An in vitro study

“…1 ), and received a customized hemispherical loading abutment. The protocol used is similar to that described in a recent paper ( 14 ).…”

“…This procedure was similar to that described by Leitão-Almeida et al . ( 14 ), except for the amount of implant inserted in the resin and the length of the load abutment. In brief, 7.5 mm-high metal hemispheric load abutments (n=32) were placed on each implant using prosthetic screws (Avinent® Implant System, Santpedor, Spain) at 32 N/cm.…”

“…It is therefore important to determine whether IP is a safe technique that does not compromise the long-term prognosis of dental implants. Several in vitro reports seem to indicate that IP does not significantly reduce the mechanical resistance of dental implants ( 13 , 14 ). However, a number of other variables may also affect this parameter.…”