Ligature-induced peri-implant infection in crestal and subcrestal implants: a clinical and radiographic study in dogs

Bone defect development in experimental canine peri-implantitis models: a systematic review

PURPOSE

To provide a systematic overview of preclinical research regarding bone defect formation around different implant surfaces after ligature-induced peri-implantitis models in dogs. Two focused questions were formulated: 'How much bone loss can be expected after a certain time of ligature induced peri-implantitis?' and 'Do different implant types, dog breeds and study protocols differ in their extent of bone loss?'

MATERIALS AND METHODS

A systematic literature search was conducted on four databases (MEDLINE, Web of Science, EMBASE and Scopus). Observations, which consisted of bone defects measured directly after ligature removal in canine models, were included and analysed. Two approaches were used to analyse the relatively heterogeneous studies that fulfilled the inclusion criteria. First, separate simple linear regressions were calculated for each study and implant surface, for which observations were available across multiple time points. Second, a linear mixed model was specified for the observations at 12 weeks after ligature initiation, and assessing the potential influencing factors on defect depth was explored using lasso regularisation.

RESULTS

Thirty-six studies with a total of 1082 implants were included after. Bone loss was determined at different time points, either with clinical measurements radiographically or histologically. Different implant groups [e.g. turned, sand-blasted-acid-etched (SLA), titanium-plasma-sprayed (TPS) and other rough surfaces] were assessed and described in the studies. A mean incremental defect depth increase of 0.08 mm (SD: -0.01-0.28 mm) per week was observed. After 12 weeks, the defect depths ranged between 0.7 and 5 mm. Based on the current data set, implant surface could not be statistically identified as an essential factor in defect depth after 12 weeks of ligature-induced peri-implantitis.

CONCLUSION

Expectable defect depth after a specific time of ligature-induced peri-implantitis can vary robustly. It is currently impossible to delineate apparent differences in bone loss around different implant surfaces.

Detection of T. forsythia and other important bacteria in crestal and subcrestal implants with ligature-induced peri-implant infection in dogs

BACKGROUND

The study was designed to compare peri-implant microbial colonization of inflamed implants placed at different levels in dogs.

METHODS

Two screwed-in (SI) and two tapped-in (TI) conical connection implants were placed on each side of mandibles in six dogs respectively. Four experimental groups were constituted according to implant types and placement depth in one side: SI crestally (SIC), SI 1.5 mm subcrestally (SIS), TI crestally (TIC), and TI 1.5 mm subcrestally (TIS). Plaque accumulation of implants was promoted by cotton ligatures at either side randomly selected in each dog four weeks after abutment connection. Peri-implant sulcular fluid (PISF) samples were collected at 4 weeks, 10 weeks, and 16 weeks after abutment connection. Common periodontal pathogens in PISF were analyzed by PCR and realtime-PCR to investigate the influence of placement depth on microbial accumulation. The microbial results were further correlated with clinical parameters.

RESULTS

At ligatured sides, detection rates of T. forsythia and P. gingivalis increased significantly in four groups. T. forsythia levels increased significantly from baseline in four groups at ligatured sides at 16 weeks (p < 0.05). TIS group harbored significantly more T. forsythia than TIC at ligatured sides at 16 weeks (p < 0.05). At ligatured sides, probing depth was correlated to T. forsythia level in four groups as well as in total.

CONCLUSIONS

Subcrestal placement could increase the peri-implant T. forsythia level at the early stage of peri-implantitis. The T. forsythia level in the peri-implant sulcus is associated with probing depth.

Effect of implant placement depth on the peri-implant bone defect configurations in ligature-induced peri-implantitis: An experimental study in dogs

Background

The subcrestal placement of implant platform has been considered a key factor in the preservation of crestal bone, but the influence of implant placement depth on bone remodeling combined with peri-implantitis is not fully understood. The aim of this study was to assess the effect of the crestal or subcrestal placement of implants on peri-implant bone defects of ligature-induced peri-implantitis in dogs.

Material and Methods

Eight weeks after tooth extraction in six beagle dogs, two different types of implants (A: OsseoSpeed™, Astra, Mölndal, Sweden; B: Integra-CP™, Bicon, Boston, USA) were placed at either crestal or subcrestal (-1.5 mm) positions on one side of the mandible. Ligature-induced peri-implantitis was initiated four weeks after the installation of the healing abutment connections. After 12 weeks, tissue biopsies were processed for histological analyses.

Results

Supra-alveolar bone loss combined with a shallow infrabony defect was observed in crestal level implants while deep and wide infrabony defects were present in subcrestal level groups. Subcrestal groups showed significantly greater ridge loss, depths and widths of infrabony defects when compared to crestal groups (P<0.001).

Conclusions

Within the limitations of the animal study, it can be stated that the implants at subcrestal position displayed greater infra-osseous defect than implants at crestal position under an experimental ligature-induced peri-implantitis.

Key words:Subcrestal, peri-implantitis, histology.