Original study - ZZI 02/2016

The influence of various implant types on peri-implant bone loss – a retrospective radiological evaluation

With a different procedure for visualization only the calculated median value is shown, but with a confidence interval of 95 %. It is unlikely (p < 0.05) that the actual course (which should be mirrored by selection of this study population) will be outside this range.

Results

Records of 569 patients with a total of 1434 implants were evaluated. The patients included 263 men (46.2 %) and 306 women (53.8 %). Of the 1434 implants, at least one additional follow-up radiograph was available for 1261 implants (681 (54.0 %) placed in women and 580 (46.0 %) placed in men). A total of 3613 radiographs of the 1261 implants were available. Beyond the 1261 radiographs taken immediately after placement, an additional 780 (61.9 %) were taken within the first year, 335 (26.6 %) within the second year, 762 (60.4 %) between years 2 and 5, and 379 (30.1 %) between years 5 and 10. A further 96 (7.6 %) radiographs were taken more than 10 years after implant placement, bringing the total to 3613 radiographs.

Implant distribution

The implants were evenly distributed among the 4 jaw quadrants. However, bicuspids and molars predominated (34.7 %, 33.2 %), followed by incisors (22.4 %) and then canines (9.7 %). The distribution of implants according to indication is shown in table 2.

Implant types

The implant types were represented as follows: 506 (40.1 %) were Astra Tech Dental implants, 558 (44.3 %) were Camlog implants and 197 (15.6 %) came from DENTSPLY Friadent (tab. 3). Camlog and DENTSPLY Friadent products were further categorized into subgroups, according to their types of implant/abutment connection. Camlog implants were divided into Morse taper (Conelog) and internal connection (Camlog), whereas DENTSPLY Friadent were divided into internal connection (Frialit/XiVE) and transgingival systems (Frialoc/Xive TG). The distribution of these subgroups is depicted in table 4.

Bone loss – Progression

Depiction of the bone loss measurements in a diagram revealed a relatively large degree of variance. Delimitation using the quantiles showed that in each case, 95 % of the measurements were within the respective corridors. The median bone cavity depth on the immediately post-surgical radiographs was –0.107 mm, while after 17.5 years it was almost 2 mm. Most of the bone loss occurred during the first 2 years. After that, bone loss decreased to almost zero.

Although the distribution of implants in the upper and lower jaw was nearly identical (51.4 % and 48.6 % respectively), the resorption kinetics in the 2 jaws appeared to be different. More rapid bone loss was registered in the upper jaw than in the lower. Taking all implants into account, the majority of bone loss occurred during the first year (fig. 3). When the results of the individual indication classes (tab. 2) are transferred to a diagram, it is apparent that implants replacing lost support teeth to ensure continued functioning of the prosthesis (IBrep) and those placed in edentulous lower jaws (ELJ) caused less bone resorption than those placed for single crowns, bridges and in edentulous uppers.

Implant length and diameter

The implant length also appeared to have a noticeable influence on bone loss, with shorter implants exhibiting fewer signs of bone resorption than longer ones (fig. 4). This difference was significant (p < 0.05) for implants ? 9 mm. No significant differences were observed for implants > 9 mm. The diameter of the implants appeared to have a similar effect. The more slender the implants were, the smaller the bone cavity (fig. 5). A significant difference was also established when comparing the implants with a diameter ? 3.5 mm to all others, and this also applied to implants with a diameter exceeding 5.0 mm (p < 0.05). No significant differences were established when comparing implants with diameters ranging between 3.5 mm and 4.1 mm to those between 4.1 mm and 5.0 mm.

The influence of implant types

The results of this study revealed different bone loss situations for specific implant types. After 4 years, Camlog implants exhibited 2 mm mean bone loss, while DENTSPLY Friadent products did not reach this value, even after 10 years (fig. 6, 7). The Astra Tech Dental implants exhibited virtually no bone cavities (fig. 8). After 10 years, values were still below 0.5 mm.

Comparison between Camlog implants and the Conelog version highlighted a serious difference. Morse taper Conelog implants led to significantly (p < 0.05) fewer signs of bone loss than the tube-in-tube connected Camlog implants, even if the observation period is short (fig. 9).

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