implants - internationalmagazine of oral implantology

I clinical study _ flapless implant surgery Fig. 13_Peri-implant soft tissue be- fore prosthetic restoration (Z-Look3). Furthermore, the clinically measurable PD was analysed,thusallowingconclusionsconcerningthe inflammatory status of the peri-implant tissue (Shouetal.2002).ThePDmeasurementisoneofthe most important parameters for clinical characteri- sation of the implant condition (Behneke et al. 2002).Itisofcentralimportancealsobecauseofthe similarity of the tissues surrounding teeth and im- plants. The value measured is related to marginal bone loss (Quirynen & Listgarten 1990). For natural dentition,aPDof1to3mmisconsideredtobephys- iological, though around implants the healthy or pathological values vary. A PD of 1.5 to 3.5 mm was foundtobeoptimalbyBehnekeetal.(1997).Theval- uesfoundinourstudyaresignificantlydifferent.Al- thoughthemeanPDwasnotinfluencedbythepres- enceofAGinthecaseofStraumannimplants,i.e.PD remained constant at 2.4 mm, for Thommen im- plantsasignificantdifferencewasfound.Itneedsto be emphasised that the polished collar height of the Straumann implants used was 1.8 mm (Standard+) and 2.8 mm (Standard), whereas for Thommen im- plants this was 1.5 mm (CONTACT) and 1 mm (ELE- MENT).Onecanonlyspeculatethatthepolishedcol- lar of 1.8 mm and 2.8 mm together with keratinised AGmayleadtoareducedPDandalsoslightlyhigher BOP. On the other hand, shorter polished collars are preferred prosthetically because in the long-term they lead to an aesthetically more favourable out- come. The analysis presented has also shown that in the presence of keratinised gingiva, minimally inva- sivetransgingivalimplantationledtostableimplant integration with respect to soft tissue. The PD values measured in this study (overall mean of 2.4 mm) are comparable to published re- sults. A PD of 2.2 mm that remained constant over four years was reported (Becker et al. 2009). This value seems reasonable when considering the anatomicalparodontalstructures.Similartonatural teeth, biological width is formed around implants too. This begins at the implant–abutment interface and ends, as with natural teeth, at the limbus alveo- laris (Buser et al. 1989, 1992; Ericsson et al. 1996; Cochran et al. 1997; Hermann et al. 1997; Abra- hamsson et al. 1997; Kohal et al. 1999; Hermann et al.2000).Itisknownfromanimalstudiesthatthedi- mensions of biological width are similar around im- plants and natural teeth (Buser et al. 1989, 1992; Cochran etal. 1997; Ericsson etal.1995). The height of the implant–mucosal complex is 3 to 4.8 mm and thedimensionsofitscomponentsseemtovarymore aroundimplantsthanaroundteeth(Berglundhetal. 1991; Hermann et al. 2000). Our results confirm these findings; the most frequent PD values were 2 and 3 mm. This corresponds well with the published biological width (Berglundh etal. 1991; Weber etal. 1996). The consequence of frequent abutment re- placement was a more apically attached connective tissueandincreasedincidenceofmarginalboneloss (Abrahamssonetal.1997,2003).Transgingivalheal- ingwithimmediaterestorationoftheimplantshelps toreducethefrequencyofabutmentchanges;itmay hence lead to more stable bone levels. Asmentionedabove,onefemalepatienthadaPD of 8 and 9 mm with pus secretion. This occurred in the presence of a symptomatic bisphosphonate-re- lated ONJ at already osseointegrated and restored implants.ThepatienthadbeentakingZolendratefor three years as an adjuvant therapy for mammary carcinoma.Shedidnotreportthisanditwasonlyre- vealedbyinquiryofheroncologist.Theinfectionre- solved after systemic antibiotics and careful local treatment.Todate,theimplantsareinsituandsymp- tom free. Following minimally invasive insertion of tita- nium implants, in most cases healthy peri-implant tissuewasfoundinthisstudy.BOPwasseenforonly 14.9% of Straumann implants, compared with 38.2%ofThommenimplants.Thisdifferencemaybe explainedbythehigherpolishedcollarofStraumann (2.8 mm and 1.8 mm) in comparison with Thommen implants(1.5mmand1mm).InthesamewayasPD, this finding can be related to the height of the mu- cosal implant complex. Histological investigation (notfeasiblewithinthescopeofthisstudy)wouldbe needed to confirm this assumption. The influence of the micro-gap (50–100µm for mostcommercialimplantsystems)betweentheim- plant and its abutment (or secondary prosthetic parts) is controversial. The micro-gap can be popu- lated by bacteria and thereby affect both the peri- implant bone loss and the peri-implant soft tissue (Scaranoetal.2005).Clinicalstudiesthatcompared one- and two-piece implants have found signifi- cantly more inflamed sites around two- piece than around one- piece implant systems (Broggini et al. 2003).Suchatrendwasalsoconfirmedinthisstudy. 16 I implants4_2011 Fig. 13