改良螺紋設計之植體對骨整合影響之評估

Abstract

近年來植體表面處理技術的進步，使得人工植牙之癒合時間縮短,成功率也大幅提高,但再完美之表面處理，仍需要一定的癒合時間，若要使植體之初期穩定度提高，植體局部構型，如螺紋設計之改良，或可能扮演一定的角色，因此局部構型及表面處理與對植體之初期穩定之提供及後續骨整合之效果可能扮演一定的角色。 本研究之目的在評估不同螺紋設計，但同樣以SLA酸蝕處理表面之人工牙根其初步穩定度及對後續骨整合之影響。 其方法為以複合表面螺紋構型之人工牙根及傳統螺纹構型之人工牙根以動物實驗模式進行比較，3隻Beagle犬，於下顎牙齒拔除(P2,P3,P4)後，植入複合表面螺紋人工牙根5根，並以傳統螺纹構型人工牙根3根作為對照組進行比較， 於植體植入前後進行臨床評估，共振頻率測量及影像紀錄等之評估，並於植入後之四周，八週及十二週等時間點犧牲動物，進行組織標本觀察。 結果顯示 具複合表面螺紋構型之人工牙根 在植體植入時有較大之旋入扭力，術後當次以共振頻率測量實驗組與對照組間，實驗組略優於對照組，但並未達到統計上的顯著。但術後之觀察 複合表面螺纹構型確有較高植體牙周炎之比率，甚至有植體脫落之情況 (2根，佔實驗組13.33%)， 惟就組織學及病理切片之結果來看， 兩者於骨整合及骨接觸並未呈現統計上之差異。 以現有之結果而言 兩種植體之存活率均可達 85 % 以上，改良型之植體之表面螺纹構型或可能有較高之初期穩定度，但並未能加速骨整合之效果， 其原因可能與鑽針之設計， 置備之植體創口大小及過大之應力集中導致後續骨吸收及牙冠周圍炎有關。 結論：複合螺纹構型未必能提供未能加速骨整合之效果，對於相匹配之鑽針之設計應更謹慎，才能充分呈現複合式螺紋設計之優點。

Objectives Surface design and treatment on dental implant had been progressed rapidly, which caused reduction of healing time and raise of successful rate. Successful treatment with dental implant depends on a direct contact between dental implant and surrounding bone, which is known as osseointegration. Since the initial stability of implant was related to osseointegration, the geometric design on implant surface may play an important role in improving of initial stability of implant thus enhancing the osseointegration. The purpose of this study is to evaluate the influence of modified thread design on osteointergration.

Materials and methods Two different implant thread designs, the simplex type (ITI), and complex type (Biodenta) with same length (8mm) , diameter(3.3mm), surface treatment (SLA), were used in the present study. A total of 24 implants were inserted into the edentulous ridge in oral cavity of 3dogs and assigned into three healing periods, 4weeks, 8weeks and 12weeks. Each dog received implantation of 8 implant, which included 5 implants of complex type (Biodenta) and 3implants of simplex type(ITI). The assessments of implants are including clinical evaluation, resonance frequency analysis (RFA), and photographic record. And the dogs were sacrificed at the time interval of 4, 8,12 weeks after implantation for further histological analysis.

Results It showed that implants of complex thread design had greater torque value during insertion. There was no statistically difference in initial stability, even though the ISQ value of implant with complex thread design was higher than simplex group. Furthermore there were two implants of complex group dislodged spontaneously leading to lower initial survival rate in complex group (86.67% in simplex group vs. 100% in complex group, p<0.05). However, there was no statistically difference in osseointegration and bone-implant-contact among two groups by means of histological analysis. In the present study, the survival rate of either group was above 85%. Although superior initial stability in complex type implant group, the outcome of osseointegration was not as good as expecting. It seems that factors rather than design of implant such as the diameter of the drills, stress distribution around the implant preparation site might lead to fair osseointegration result. While a new complex implant system development, it seems be cautious on the design and stress distribution around the implant preparation site is warranted.