Cement retention has been widely used for implant-supported fixed partial dentures in daily dental practice. The cementation approach indeed offers straightforward clinical application protocol which is basically conceptualized for tooth/teeth supported fixed restorations. However, removal of excess cement around implant restorations presents specific difficulties. More importantly, there are certain biological consequences due to residual cement leftover in peri-implant sulcus. There is no evidence based guidance with regards to cementation techniques applied for implant supported fixed restorations due to limited clinical studies. Therefore the aim of this clinical trial is to compare three different cementation technique with regards to removal of excess cement and other clinical subsidiaries (abutment margin, crown surface and contour) involving indirectly as well.

Single-tooth implant crowns to replace missing molar tooth were addressed to qualify and quantify residual cement on implant-abutment complex and peri-implant soft tissue following cementation. Thirty bone-level dental implants of one kind enrolled in the study. Prior to delivery of screw-retained crowns completed for usual treatment, implants were allocated randomly to a trial comparison group. Three different cement loading approach, ten in each group, was applied using cement-retained trial crowns on prefabricated metal abutments. Following completion of the assigned cementation technique, the trial crown was removed with its abutment accessing from the occlusal hole prepared after removal of excess cement. Then, the presence of residual cement on implant-abutment complex and implant soft tissue in accordance with axial and proximal surfaces was qualified. To quantify the amount of residual cement in accordance with location and distribution, the crown-abutment complex was digitized three-dimensionally using an intra-oral scanner. The output of surface data was evaluated in virtual 3-D image for cement excess, when detected location in the abutment-crown complex is recorded, area and distribution was calculated using a software. The frequency of occurrence and quantity of residual cement of 3-different cementation techniques was statistically evaluated using logistic and linear regression model separately considering abutment margin, crown surface and contour.

Inclusion Criteria:

• completed growth and development
• periodontally and dentally healthy conditions
• missing single molar tooth without free-end edentulism
• bone-level standard diameter of a specific implant from one manufacturer
• complication free healing period for osseointegration following straightforward surgical implant placement
• natural dentition or fixed restoration in dental arch
• signing of informed consent form

Exclusion Criteria:

• absolute systemic contraindications for implant surgery (e.g. bone cancer, radiation therapy)
• relative systemic contraindications for implant surgery (e.g. diabetes, steroid therapy)
• risk factors (e.g. smoking, limited mouth opening)