CAMLOG and Science

CAMLOG&Science – Chapter 4 PRE-CLINICAL STUDIES Various pre-clinical studies have been performed to evaluate the biological behavior and reliability of the CAMLOG ® and CONELOG ® Implant Systems in vivo. Design changes and developments to improve the formation and maintenance of the soft and hard-tissue structures have systematically been tested in animal studies to prove their state-of-the-art technology. IMPROVEDOSSEOINTEGRATIONWITH CAMLOG ® PROMOTE ® PLUS DESIGN The machined surface segment of the CAMLOG ® SCREW-LINE implant neck was significantly reduced from 2.0 mm (Promote ® ) to 0.4 mm (Promote ® plus). Schwarz et al. (2008) investigated the effect of this design change on crestal bone resorption in a dog study. Both implant types were inserted in the man- dibles of dogs following the standard protocol (0.4 mm above the bone crest). Histological evaluation took place after 2 and 12 weeks. Bone changes were found in both implant types after 12 weeks. However, the coarse neck area in the SCREW-LINE Promote ® plus implants appeared to have a positive effect on marginal bone growth. Data demonstrated that the new surface design efficiently reduced crestal bone changes. Another conclusion was that when a native thick gingiva was available, an approximately 1 mm higher bony in- tegration level of the implant could be accomplished without the marginal epithelium reaching the microstructured surface (Becker et al., 2006). EFFECT OF MICROLEAKAGE ON CRESTAL BONE RESORPTION Microgaps in the implant-abutment connection have been supposed to play a critical role in the crestal periimplant bone loss observed during the first year of loading. Steinebrunner et al. (2005a and b) hypothesized that the implant-abutment connection may be a reason for the different bacterial penetration profiles of various implant systems. Schwarz et al. (2008) detected only a mild inflammatory cell infiltrate at the implant-abutment interface of both implants, which was divided from the alveolar bone crest by an intact connective tissue zone (Fig. 14). The authors concluded that microleakage played no part in marginal bone resorption in the two groups. CAMLOG K-SERIES: EFFECT OF PLATFORM SWITCHING DESIGN Platform switching is intended to increase the distance between the im- plant-abutment interface and the alveolar crest and thereby decrease the effect of inflammatory cell infiltrates on bone resorption. The principle of platform switching in the CAMLOG ® Implant Systemwas evaluated in a dog study over six months (Becker et al., 2009). SCREW-LINE Promote ® plus im- plants (K-series, ø 3.8 mm) were inserted according to the standard surgical protocol (Fig. 15A: Wide-body matching healing abutments ø 3.8 mm, H 4 mm, standard configuration) and non-matching abutments (Fig. 15B: ø 3.2 mm, H 4 mm, platform switching configuration) were connected in a randomized split-mouth design and served either as control or test implants with a circumferential horizontal platform of 0.3 mm, respectively. The histological evaluation after four weeks demonstrated formation of mature woven bone in the gap between the alveolar bone and the implant surface in both groups. A first tendency for crestal bone changes was noticed in both groups. At 12 weeks, mainly mature lamellar bone was found. Bone loss tended to be slightly increased for the control implants compared to the platform-switched implants. The difference between control and test im- plants regarding the distance between implant shoulder and bone crest (IS-BC) was 0.5 mm at the buccal aspect and 0.4 mm at the lingual aspect (p < 0.05), respectively. A similar result could be observed at six months when remo- delling at the alveolar crestal bone seemed to decline (Figs. 15C and 15D). The difference of IS-BC between both groups was settling down to approximately 0.3 mm. The study demonstrated that the CAMLOG ® implant design (K-Series) both in its standard and in its platform switching configuration successfully integrated into hard and soft tissue. Bone remodelling as well as soft-tissue adaption appeared to beminimal at the implant-abutment interface during the first eight weeks of osseointegration and considerably less pronounced after sixmonths resulting inastablecrestal bone level. Theplatform-switched implants tended to yield better results regarding maintenance of the bone level. Fig. 14: Histological pictures after 12 weeks healing of (a) Promote ® and (b) Promote ® plus CAMLOG ® SCREW-LINE implants (200x magnification, toluidine blue stain). The apical extension of the inflammatory cell infiltrate (aICT) and the level of the alveolar crest are clearly divided from each other by an intact connective tissue zone with parallel collagen fibers and a few formed blood vessels; IC = implant shoulder (reproduced from Schwarz et al. 2008; with kind permission of Quintessence Publishing Co, Inc, USA).