This study was designed as a randomised, controlled, split-mouth trial. all enrolled patients needed single bilateral fixed implant-supported prosthesis in molar area.

A total of 18 consecutive patients were enrolled. In each eligible patient, the right molar was randomly selected to receive either Nobel Replace Tapered Groovy implant; (Nobel Biocare®, Goteborg, Sweden) with Platform Switching (PS) or Regular Platform (RP)

This study was designed as a randomised, controlled, split-mouth trial. all enrolled patients needed single bilateral fixed implant-supported prosthesis in molar area.

A total of 18 consecutive patients were enrolled. In each eligible patient, the left molar was randomly selected to receive either Nobel Replace Tapered Groovy implant; (Nobel Biocare®, Goteborg, Sweden) with Platform Switching (PS) or Regular Platform (RP)

Both sites received tapered implants with an anodised surface, one site received: Nobel Replace Tapered Groovy PS implant; (Nobel Biocare, Goteborg, Sweden), with diameters of 4.3 or 5.0 mm and lengths of 10 or 8 mm, (PS group), the contralateral site received Nobel Replace Tapered Groovy implant with Replace Select connection with diameters of 4.3 or 5.0 mm and lengths of 10 or 8 mm, (RP group).

Healing abutments were connected to implants at the same time of surgery , then flaps were sutured with Vicryl 4.0 sutures (Vicryl, Ethicon J&J International, St-Stevens-Woluwe, Belgium).

implant survival: The removal of implants was dictated by instability, progressive marginal bone loss, infection or implant fracture.

Marginal bone levels: Peri-implant marginal bone levels were evaluated on intraoral digital radiographs taken with the parallel technique at the time of implant placement, at 6 months and 12 months.

If radiographs were inconclusive, they were repeated. A blinded radiologist (F.G.), unaffiliated with the study centre, interpreted all radiographs. The distances from the mesial and distal interproximal bone to the reference point (the horizontal interface between the implant and abutment) were measured with a software measurement tool (NIH Scion Image programme version 4.0.2, Frederick, MD, USA) calibrated against the space between two threads to the nearest 0.1 mm, and the mean of these two measurements was calculated for each implant. The measurements were recorded with reference to the implant axis.

Peri-implant mucosal response: Probing pocket depth (PPD) and bleeding on probing (BOP) were measured by a blinded operator (A.D.) with a periodontal probe (PCP-UNC 15, Hu-Friedy Manufacturing, Chicago, IL, USA) at 6 and 12 months. Three vestibular and 3 lingual values were collected for every implant by the same dentist.