Abstract
Peri-implantitis can be managed successfully by surgical debridement and mechanical
removal of the exposed implant thread in certain scenarios to facilitate implant
maintenance and home care. However, one of the side effects of this procedure is the
reduction of the implant diameter, which may affect the fracture resistance of the dental
implant.
Objectives
This thesis aimed to explore the effect of implantoplasty on the fracture resistance of
dental implants. This includes a literature and systematic review on dental implant
fracture after implantoplasty, as well as in vitro and finite element analysis experiments
which evaluated the effect of various degrees of implantoplasty on fracture resistance.
This study also investigated the surface changes of dental implants after implantoplasty.
Methods and Materials
For the systematic review, appropriate keywords related to implantoplasty and fracture
resistance were used to search for relevant articles in three electronic databases
(MEDLINE, Scopus, and Embase) up to August 29, 2021. This identified all studies that
assessed the effect of implantoplasty on the fracture resistance of dental implants.
Guidelines provided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane Collaboration were followed. This systematic review
addressed a focused question: “Will implantoplasty affect the fracture resistance of
dental implants?” using the PICO method.
The in vitro study included 80 standard diameter dental implants, which were divided
into control (without implantoplasty) and test groups (with implantoplasty). Further
division was based on the height of the simulated bone loss (3 mm and 5 mm) and the
degree of bone loss (semi-circumferential and circumferential). Implantoplasty was
carried out by one operator (R.G.) using tungsten carbide finishing burs made specifically
for this procedure. Changes in the implant after instrumentation were assessed using four
methods. Weight changes were measured using a microscale while surface roughness
was quantified using a profilometer. Optical microscopy was done to evaluate the implant
surface and three-dimensional analysis was done to quantify the changes in the volume of each implant after implantoplasty. Finite element analysis was also carried out to
assess the distribution of stress amongst the abutments and implants under loading.
Results
For the systematic review, ten studies which evaluated the effect of implantoplasty on the
fracture of dental implants were identified and analysed. As there were multiple
confounding factors such as the difference in implant diameter, connection design, and
extent of bone loss between studies, the exact influence of implantoplasty on fracture
resistance was still uncertain. However, the available evidence indicated that narrow
diameter implants with an internal hexagon connection may be more likely to fracture
after implantoplasty. Factors that lead to an increase in implant strength include
implants made of titanium-zirconia alloy and implants with bone level design.
The present in vitro study found significant differences in weight and volume between
circumferential and semi-circumferential implantoplasty (p = 0.001 and 0.003).
Statistically significant associations between volume and weight and fracture resistance
were detected for all groups. Overall, implantoplasty reduced the fracture resistance of
dental implants regardless of the degree of implantoplasty and defect morphology, apart
from the group with 3 mm of circumferential bone loss (p = 0.123). Implants with 5 mm
of simulated bone loss fractured with less force compared to implants with 3 mm of
simulated bone defect before and after implantoplasty in both circumferential and semi-circumferential groups (p < 0.001). In the semi-circumferential implantoplasty group,
only implants with 5 mm of bone loss experienced a significant decrease in fracture
resistance compared to circumferential implantoplasty (p < 0.001), which was not
observed in the 3 mm bone loss group (p = 0.482). Implant surface roughness decreased
significantly (p = 0.000931) following implantoplasty. Finite element analysis
demonstrated the reduction of maximum stress exerted on the abutments and implants
after implantoplasty.
Conclusions
Possible characteristics of dental implants which can lead to significantly reduced
fracture resistance after implantoplasty included narrow diameter implants and
implants with internal hexagon connections.
Implantoplasty on 4.2 mm diameter dental implants with 3 mm and 5 mm of
circumferential and semi-circumferential simulated bone loss significantly reduced the
fracture resistance. The only group of dental implants which did not experience a
statistically significant reduction in fracture resistance had 3mm of circumferential bone
loss. A greater amount of exposed implant threads and implantoplasty led to a decrease
in fracture resistance. Dental implants presenting with a semi-circumferential pattern of
bone loss were also more resistant to fracture after implantoplasty compared to those
with circumferential bone loss, especially in implants with a greater amount of bone loss.
As all available studies on this topic are in vitro in nature, there is still no evidence to
suggest that implantoplasty increases the risk of dental implant fracture in patients due
to the various limitations of in vitro studies. The type of suprastructure connected to the
implants, degree of edentulism and presence of parafunctional habits will affect the
magnitude and direction of stress on dental implants. To ascertain the clinical impact of
implantoplasty on the fracture resistance of dental implants, clinical studies to identify
its prevalence are required.