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ePaper created 2014-11-23, 21:56:20 | version 1.30.01
I research 12 I implants4_2014 Radiographicmarginalbonelevelassessment Routine periapical radiographs were deemed unnecessary; therefore, in order to check that os- seointegration was uneventful, radiographs were takenatsixmonthsandtwoyearsaftersurgery.Care was taken to use the parallel–perpendicular tech- nique; that is, the sensor holder was placed parallel toandtheradiographtubeperpendiculartotheim- plant axis to ensure optimal projection for each pa- tient. Particular attention was given to obtaining a radiographthatwouldshowtheapexoftheimplant andtheocclusalaspectofthecrowninordertoeval- uate the clinical root–crown ratio. Along with the clinical check, the radiographs were used for quan- titative bone-level evaluation. This was done by a single evaluator (PZ) using ImageJ (National Insti- tutes of Health, current version). The images were scaled using the known implant thread height.27 Results Fifty-six patients received 77 short implants. The average patient age at implantation was 59 (34–77) years.Onepatientwasonanticoagulanttherapyand one had a cardiovascular disease. Two patients un- derwentsimultaneousboneaugmentationwithde- proteinised bovine bone mineral and autogenous bone as filling material. Forty-three (56%) implants were placed in the maxillae (15–17, 25–27) and 34 (44%) in the mandible (35–37, 45–47). Of the 77 implants placed, 16 (21%) had a plat- form diameter of 4.0 mm, 37 (48%) of 4.5 mm, 17 (22%) of 5.0 mm and seven (9%) of 6.0 mm. In two of the three participating centres (DA and JH), the maximal insertion torque using the MONO torque ratchet(ThommenMedical)wasrecordedfor40im- plants. Sixteen implants (40%) were inserted at 20Ncm, 22 implants (55%) at 30 Ncm and two im- plants (5%) at 35 Ncm, suggesting good bone qual- ity at the inserted sites. This corresponded well with thefactthatnoimplantwaslost,thatis,anapparent 100% implant survival rate. The radiographic evaluation of the peri-implant bone height confirmed the remarkably stable bone level achieved with the use of this implant (Fig. 1).27–29 The peri-implant bone level stabilised at 0.9 ± 0.5 mm (mean ± standard deviation) beneath the microgap, that is, beneath the implant–abut- ment connection. The implants used have a 1.0 mm machined collar. Therefore, in this patient popula- tion, the bone level also stabilised at the interface to the moderately rough endosteal surface. One patient, a 74-year-old female patient in the cohort reported above, presented with a partially edentulous right posterior mandible. The teeth had been extracted more than three months before and threeimplantswereplacedintothehealedsites.Ow- ing to the limited distance from the nerve channel, that is, to avoid the risk of its injury, short implants were inserted in replacement of the second premo- larandfirstmolar(positions45and46).Theimplants were covered with healing abutments. After two months of uneventful transgingival (non-submerged) healing, the healing abutments were removed (Figs. 2a & b) and the soft tissue around the implants was found to be fully condi- tioned. A periapical radiograph was taken that con- firmed the absence of any pathological signs (not shown). An open-tray impression was taken. The frameworkwasscrewattachedtoensurethatapas- sivefitwasachieved,theocclusionchecked,andthe permanent restoration (Fig. 3) completed and screw attachedwithintwoweeksofremovalofthehealing abutments. An intra-oral photograph taken after two years of function demonstrates the very favourable and predictable outcome (Fig. 4). _Discussion Recently,shortdentalimplantshaveproventobe as successful as longer implants. This improve- ment30 canbeexplainedbytheuseofshortimplants for specific indications and the improved initial di- agnosis resulting from the widespread use of CBCT, which has been available since the turn of the cen- tury, improved implant design and our ability to identify risk factors for peri-implantitis.31, 32 The availability of diagnostic tools with improved accu- racythatenablemorewidespreadmanufacturingof Fig. 3_Permanent bridge (porcelain-fused to metal) before insertion. Fig. 3