The effect of opposing structures, natural teeth vs. implants on crestal bone levels surrounding single-tooth implants.

OBJECTIVES

To evaluate the effect of opposing structures in crestal bone levels around single-tooth implants.

MATERIALS AND METHODS

A retrospective cohort study design was conducted. Descriptive statistics, univariate and multifactor mixed-effects regression models, adjusted for multiple implants in the same patient were utilized to evaluate the effect of opposing structures in crestal bone levels after insertion of single-tooth replacements.

RESULTS

Eighty-one subjects who received 320 Bicon implants were included in the present study. Two hundred and thirty-one implant restorations were opposing natural teeth, 75 implants were opposing implant-supported restorations, 10 implants had no opposing structure and four implants were opposed by a complete denture. The average change in crestal bone levels overtime (AvBL) on implants opposing natural teeth and implant-supported restorations was -0.20 and -0.62 mm, respectively. Hydroxyapatite-coated (HA) mandibular implants opposing natural teeth demonstrated AvBL of +0.01 (indicating bone gain), whereas titanium-plasma sprayed (TPS)-coated mandibular implants opposing implants restored with composite abutment bases demonstrated AvBL of -1.95 mm. When the structure opposing an HA-coated mandibular implant was a natural tooth, it was a predictor of peri-implant bone gain (P = 0.007). While TPS-coated mandibular implants, which had been restored with composite abutment bases, were correlated with peri-implant bone loss when opposed by implant-supported restorations (P = 0.003).

CONCLUSIONS

This study suggests that the type of opposing structure plays a significant role in mandibular crestal bone levels surrounding single-tooth implants following crown insertion but this effect differ around implants with dissimilar surface coatings and can be exacerbated by local irritating factors.