Purpose: The aim of this study was to evaluate the clinical outcome of all-zirconia double-crown retained complete mandibular overdenture on two natural abutments regarding peri-abutment tissue health and periodontal microbiota.

Materials and methods: Ten completely edentulous patients with only remaining mandibular two canines were included in this study. All patients were scheduled to receive maxillary conventional complete denture against double-crown retained mandibular complete overdenture. After root canal treatment of canines, they were prepared to receive the primary copings. The model of the prepared abutments was scanned, and zirconia primary crowns were fabricated with standardized parameters using the CAD CAM (Computer aided designing- computer aided manufacturing) technology. Primary crowns were evaluated in the patient’s mouth and repositioned on the model for rescanning. Secondary crowns were virtually designed to provide non-rigid telescopic attachment design. Data were transferred to the CAM program for milling of the zirconia secondary crowns. Primary copings were cemented to canine abutments and secondary copings were secured to primary ones to record a final impression and construct a master cast over which the overdenture was constructed. Refining of occlusion was done and secondary copings were functionally picked up into the mandibular denture fitting surface. Clinical and microbiological evaluation of the two canines was done at the time of denture insertion (T0), 6 weeks (T6) and twelve weeks (T12) later. Data were collected and statistically analyzed.

Result: After 12 weeks of overdenture use, no statistically significant difference was found in all measured peri-abutment soft tissue parameters (gingival index, plaque index and probing depth), no loss of clinical attachment was observed, and periodontal microbiota related to abutment teeth was not significantly changed.

Conclusion: Within limitations of this study, it could be concluded that all zirconia double-crown attachments could be considered a biologically promising retainer for natural abutments overlaid dentures.

 

Keywords: Double-crown attachment, Zirconia, Tooth overdenture.