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Journal of Oral Science & Rehabilitation No. 4, 2016

Journal of Oral Science & Rehabilitation 66 Volume 2 | Issue 4/2016 E f f e c t s o f i n s e r t i o n t o r q u e o n h a r d a n d s o f t t i s s u e a f t e r t w o y e a r s 0.2% chlorhexidine mouthwash (for 1 min b.i.d. fortwoweeks).Thepatientswererecommended to avoid brushing andtrauma and anyremovab- le prostheses were removed. Afterten days, the sutureswere removed and oral hygiene instruc- tions were given. The implantswere leftto healsubmergedfor three months. Subsequently, the implants were exposed and impressions were taken using the ITAB transfer/abutment (Intra-Lock Internatio- nal) with an individual tray and polyvinyl siloxa- ne material (Flexitime, Heraeus Kulzer, Hanu, Germany). Implant abutmentswere customized and definitive metal–ceramic crowns were ce- mented. Periapicalradiographsweretaken,with the parallel cone technique with a digital sensor (70 kVp, 7 mA), at baseline (immediately after implant insertion) and at three, six, 12 and 24 months after implant placement. The patients were enrolled in an oral hygiene program with recallvisitseveryfourmonthsfortheentiredura- tion of the study and an independent observer performed all of the follow-ups. Va r i a b l e s Sample description variables The samplewas described bythefollowingvari- ables: age; sex; smoking habit; location, length andinsertiontorqueofdentalimplant;andthick- ness of the residual buccal bone plate after os- teotomy.Thefollowingnumericalvariableswere evaluated: – Insertion torque (IT): The ITwas registered at the time of surgery by a digital torque gauge (BTGE 10CN), after each turn of 90° of the implant. Subsequently, the mean IT was cal- culated accordingtothevalues registered and to the number of turns required to fit the im- plant platform to the level ofthe crestal bone. – Buccalbonethickness(BBT):Theresidualbone thickness on the buccal aspect of the implant osteotomypreparationwasmeasuredatbase- line at the midfacial level of the buccal bone plate using a surgicalcaliper.Two groupswere identified according to the BBT: Group A with a thickness < 1 mm and Group B with a thick- ness ≥ 1 mm. Outcome variables Allothermeasurementswere acquired immedi- ately at the time of surgery (baseline) and at three, six, 12 and 24 months afterdentalimplant insertion.Asinglewell-trainedclinician,whowas notinvolvedinthesurgicaltreatment,registered all of the measurements. The following outcome variables were regis- tered: – Periimplant marginal bone level (MBL) at the mesial and distal sites: The distance between the reference point and the most apical point of the MBL was evaluated on intraoral radio- graphs. The reference point was the fixture platform. A paralleling device and individual- ized bite blocks, made of polyvinyl siloxane impression material, were used for the stan- dardization ofthe X-raygeometry. Calibration was performed using the known thread pitch distance of the implants (pitch = 1 mm). Pre- vious known values, such as fixture diameter and length, were used for calibration when the threads were not clearly visible on the radiographs. Measurements were taken to the nearest millimeter using computer soft- ware (UTHSCSA Image Tool, Version 3; Uni- versity of Texas Health Science Center, San Antonio, Texas, U.S.). Changes at the MBL were evaluated for all ofthe mesial and distal aspects by subtracting the postoperative values from the respective baseline value (nΔMBL = nMBLBaseline − nMBL, with n as me- sial or distal). MBL represented the mean of the values measured at the mesial and distal aspects, and ΔMBL represented the mean of the variation in values measured at the me- sial and distal aspects. – Facial soft-tissue level (FSTL) was evaluated, measuring the distance between the level of soft tissue at the midfacial gingival level and a reference line connecting the FSTL of the adjacent teeth. Facial soft-tissue changes were calculated by subtracting the baseline value from the respective postop- erative values according to the formula ΔFSTL = FSTL − FSTLBaseline. – Implant failure, such as implant mobility and removal of implants caused by progressive bone loss or infection: The stability of each implant was evaluated at the delivery of the prosthetic restoration and one and two years after implant insertion. The stability of each crownwas ascertainedwithtwo metallic han- dles of dental instruments. Survival and suc- cess rates were calculated according to the criteria suggested by Buser et al.14

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