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research _ implant fracture I When the patient presented recently to our clinic, theonlyportionoftherestorationthatwasstillpres- ent in his mouth was abutment #6, which was still connected to one of the fractured implants, and was removed with a hex driver (Fig. 3). Proceeding with careful assessment of all the available retrospective diagnostic information and upon further discussion with the patient, several diagnostic assumptions and one follow-up treatment option were established that included replacement of the implant-supported crowns by a removable cast partial denture. Considering the need for the removal of fractured implants must be balanced against the risk of in- creasing damage, a decision was made to remove the remaining abutment and the fractured piece of im- plant #6 allowing for primary closure of the soft tis- sueovertheremainingimplantbodies#6and#7,i.e., “put them to sleep” (Fig. 4). This was followed by in- sertion of an immediate acrylic removable partial denture, and subsequently, a cast partial denture will be fabricated. This report attempts to provide an ar- gument in favor of the consideration of physical mechanisms as potential contributors to implant fractures. Whilecontroversycontinuestoexistastowhether crown-to-root ratio can serve as an independent aid in predicting the prognosis of teeth,9 the same cer- tainly applies to crown-to-implant ratio, unless mul- tipleotherclinicalindicessuchasopposingocclusion, presence of parafunctional habits and material elec- trochemicalproblems,justtonameafew,areconsid- ered. Implant fractures are considered one potential problem with dental implants, especially delayed fracture of titanium dental implants due to chemical corrosion and metal fatigue.2 Followingcarefulreviewofthereferencedarticles, which are very enlightening, we realized that to a great extent they support our theory that there are multiple factors involved in implant fractures. These factors include magnitude, location, frequency, di- rection and duration of compressive, tensile and shear stresses; gender; implant location in the jaw; type of bone surrounding the implant; pivot/fulcrum pointinrelationtoabutmentconnection;implantde- sign;internalstructureoftheimplant;lengthoftime in the oral environment as it relates to metallurgic changes induced in titanium over time; gingival health and crown-to-implant ratio. Considering the multiple factors involved in implant fractures, both physicalandbiological,wecanonlyassumethatitcan happenespeciallyiftheforcesoftheopposingocclu- sionand/orparafunctionalhabitsaregreaterthanthe strength of the implant, especially over time. There- fore, it is imperative that the clinician be knowledge- able about the diversity of factors before recom- mendingdentalimplants.Errorsindiagnosingpoten- tial contributors to implant fractures are the most common reason that dental implants fail. _Conclusion Although, according to the literature, the use of the crown-to-implant ratio in addition to other clin- ical indices does not offer the best clinical predictors, and even though no definitive recommendations could be ascertained, considering that dental im- plantsarebecomingincreasinglypopular,anincrease in the number of failures, especially due to late frac- tures,istobeexpected.8 Thisreportattemptedtopro- vide an argument in favor of consideration of physi- cal mechanisms as potential predictors to implant fractures.Therefore,itisessentialforustofamiliarize ourselves with the understanding, and diagnostic competence of the multiple factors involved in im- plant fractures. Once observed, this predictor would certainlyleadtobetterdiagnosisandtreatmentplan- ning._ Editorialnote:Theliteraturelistcanberequestedfrom theeditorialoffice. Figs. 3a & b_By default, based on physical principles, once an implant has integrated in the bone, the weak- est point is the fulcrum where the in- ternal screw engages the implant (A). Note the fracture level in implant #7 and fracture line in implant #6 (B). Figs. 4a, b & c_The remaining abut- ment and the fractured piece of im- plant #6 were removed, allowing for primary closure of the soft tissue over the remaining implant bodies #6 and #7 (A, B), followed by an insertion of an immediate acrylic removable par- tial denture (C). (Photos/Provided by Dr Dov M. Almog) I 13implants4_2010 Dr Dov M.Almog,DMD Chief,Dental Service (160) VA New Jersey Health Care System (VANJHCS) 385TremontAve.,East Orange,N.J.07018 E-mail:dov.almog@va.gov _contact implants Fig. 4b Fig. 4cFig. 3a Fig. 3b Fig. 4a