implants international magazine of oral implantology

industry report I mandibleatthetimeofthesurgery(Fig.1).Allofthepa- tients were treated with SLA screw-shaped SEVEN and/orMistralimplants(MIS;Fig.2).Inaddition,apro- visional screwed embedded resin prosthetic appliance (Fig.3)wasfixedatthetimeofsurgeryforthetestgroup andaprovisionalembeddedresinprostheticappliance (Fig.4)wascementedatthetimeofsurgeryforthecon- trolgroup. All clinicians followed the implant manufacturer’s instructionsfortheimplantsitepreparationandinser- tion procedure. The initial primary stability was as- sessed by setting the insertion torque of the surgical unit,andrecordedaccordingtothefollowingmodified classification: “tight” when torque was greater than 45 Ncm, “firm” between 30 and 44 Ncm, or “loose” when less than 30 Ncm (adapted from Testori et al. 2002).Thelengthandthediameteroftheindividualim- plants can vary from subject to subject, depending upon bone quality and quantity at each surgical site. Thetreatmentobjectiveinvolveddeliveryoftheprovi- sional prosthesis within four hours of implant place- ment, by utilising the prosthetic procedure that best suitedtheclinicalcase.Areinforcedacrylicprovisional bridgewasrelinedoverprovisionaltitaniummulti-unit cylinders and immediately screwed onto the abut- ments for the test group. A provisional reinforced acrylicdenturewasthencementedovertitaniumabut- ments for the control group. The occlusion was care- fullychecked. No specific diet was recommended to the patients. The patients were on a strict recall programme during thefirstsixmonths:everyweekduringthefirstmonth, and every two weeks between the second and third months, and every month until the sixth month. Or- thopantograms and periapical radiographs were ob- tainedforimageanalysisatimplantinsertion.Periapi- calradiographswerealsoperformedsubsequently,af- terthree,six,12,24,48and60monthsofocclusalload- ing(Figs.5&6). Peri-implant marginal bone change was evaluated utilising a computerised measuring technique applied to intra-oral periapical radiographs (RVG, Kodak). The evaluationofthemarginalbonelevelaroundimplants was carried out using image analysis software (RVG). Thebonelossateachfollow-upvisitwascalculatedfor each implant by determining the difference between thebaselinevalues. _Results Thirty patients were enrolled in the study. Of these, ten maxillas and ten mandibles were treated with six implants(Figs.7&8)andfiveimplants,respectively,in thetestgroup(110implants),andfivemaxillasandfive mandiblesinthecontrolgroup(55implants).Fourim- plants were lost out of the 165 inserted. One implant belonged to the test group and three to the control group. The implants showed extensive marginal bone resorption and signs of peri-implantitis. The patients hadahistoryofbruxism,smokingand/orpoororalhy- giene and periodontitis. No patients enrolled in the study dropped out during the study period and all pa- tientsshowedgreatsatisfactionwiththeeffectiveness ofthetreatment. The RFA registrations showed higher values for mesial–distal measurements than for the buccal- palatalones:65.3ISQ(SD6)versus55.8ISQ(SD6.9)for allimplants.Themarginalbonelevelwassituatedmore coronally for the test implants at all stages of the trial. Aftersixmonths,themarginalbonelevelwasonaver- age0.9mm(SD1.1)belowtheimplantshoulderforthe test implants and 2.7 mm (SD 1.2) for the control im- plants.Onaverage,0.3mm(SD1)ofbonelosswasob- servedforthetestimplantsand0.8mm(SD1.2)forthe control implants during the first 12 months (p = 0.05). A similar proportion of patients showed one or more implantswithboneloss.Morepatientsandimplantsin thecontrolgroupshowed2to3mmofbonelossdur- ing these 12 months. These results were confirmed at subsequent controls at 48 and 60 months after im- plantation. _Technical complications Resin-related technical complications occurred more often in control than in test patients. Six test bridges showed a loosening of the assembly screws of theabutmentsatthethree-monthcheck-up. Fig. 3_Provisional bridge before final prosthetic steps. Fig. 4_Cemented provisional bridge in position at the time of surgery. Fig. 5_Clinical appearance after three months of occlusal loading. I 31implants2_2012 Fig. 3 Fig. 4 Fig. 5