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Journal of Oral Science & Rehabilitation Issue 01/2016

Journal of Oral Science & Rehabilitation 54 Volume 2 | Issue 1/2016 significance in the final implant stability regar- ding the two clinicians’ levels of experience for both bone qualities (soft and hard bone) and the two implant designs. The IT values were not conclusive for differ­ ences between implant design and primary sta- bility.Apparently,the sensitivityofthe ISQ meter is able to detect very small differences,19 while IT underestimates the stability values. The motor used for the evaluation of IT in this experimental studyoperatesinincrementsof5Ncm;there­fore, values below 5 N cm can be underestimated. However, the implants used had a tapered shape and this may be the main reason that the stability of the implants was similar (p > 0.05). Previous studies have shown that implants with symmetric threads and a cylindrical or tapered implant body shape have different primary sta- bility when they are placed in soft bone (paral- lel-walled implants have lower stability) and the clinician’s level of experience appears to be im- portant.1, 8 The data inthis studyconfirmthatthe tapered implant design used (Replace Select Tapered and NobelActive) may achieve excellent stability for clinicians with different levels of ex- perience in an experimental set. A recent study comparing the survival rates ofdentalimplants placed in a residencyprogram under direct supervision for the treatment of patients with overdentures has shown a high survival rate of 97.7% within a period of two years.20 The researchers concluded that novice general dentistry residents can successfully placemandibularimplantsandrestorethemwith overdentures underdirect supervision, resulting in subsequent enhancement of the patients’ satis­ faction with their mandibular dentures. However, new clinical trials by a national group of dental practitioners presented higher failure rates for implants placed by general den- tists compared with those for implants placed by clinicians with specialty training.21 For other studies, experience was defined as number of implants placed, and clinical studies showed that those clinicians (n = 1,260) with experience of placing fewer than 50 implants presented a higher failure rate of 3.5%, compared with sur- geons (n = 1,381) with greater surgical experi- ence (50 or more implants), who showed a failure rate of 1.8%.13 There is no doubt that primary stability of dental implants is of significant importance for achieving long-term success, especially when implants are loaded immediately after place- ment.22 The mechanical stability of the implant is very important, particularly in soft bone, and thethreaddesignmayprovide bettermechanical anchorage in the surrounding bone. A previous study evaluating implant stability based on the thread pitch width showed that implants with a narrow thread pitch had a higher stability owing to the greater surface area, compared with im- plants with a widerthread pitch when theywere placed in cancellous bone.23 Conclusion Within the limitations of this in vitro study, the following conclusions can be drawn: - Theoperator’slevelofexperience,expertversus intermediate, does not affect the implant sta- bilityinType IVandType II bonewhenthe same implant bed preparation protocol is used. - The stabilityoftapered implantswith symmet- ric threads and those with progressive threads is increased in Type II bone density. - The implant stability in soft bone is similar for tapered implants with a symmetric thread de- sign and for those with a progressive thread design. Competing interests The authorsdeclarethattheyhave nocompeting interests related to this study. No financial sup- port was received for this study. F a c t o r s a f f e c t i n g p r i m a r y s t a b i l i t y o f t a p e r e d i m p l a n t s w i t h d i f f e r e n t t h r e a d d e s i g n

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