implants - international magazine of oral implantology

I special _ endo-implant algorithm Fig. 6_Flat field peri-apical radiograph (left); small focal field CBCT (right; Kodak 90003D, Kodak Dental Systems). The differential in visualisation of peri-apical pathology from a 3-D to a 2-D image is as much as 2:1.62 Fig. 7_The initial endodontic treat- ment procedure was inadequate and failing. Re-engineering (inclusive of interim calcium hydroxide therapy) ensured optimal eradication of microflora from the root-canal space, and the obturation produced definitive closure of the apical termini. Surgery was performed to redress persistent symptoms. Fig. 8_The strength of the egg-like coronal structure of a tooth can support substantial occlusal stress and force; however, disrupting the integrity of the ‘dome’ or roof of the pulp chamber with an access prepa- ration will invariably lead to a statisti- cally significant degree of fracturing after endodontic therapy.16 independent of the root-canal system, surgery is the most ben- eficial treatment.33 Non-surgical retreatment may still be indi- cated in these cases, especially when intra-canal infection can- not be ruled out. Time con- straints or financial pressures should never be a factor in mak- ing surgery the first treatment choice (Fig. 7). There are a myriad of vari- ables associated with non-sur- gicalretreatment,andtreatment outcome studies in endodontics havebeenegregiouslyabusedby those wishing to diminish the value of re-engineering natural teeth. Many studies have cate- gorised teeth with caries, frac- tures, periodontal involvement and poor coronal restorations as negative endodontic out- comes.34,35 Prior procedural errors,36 oc- clusal considerations,37 material choice for the restoration38 and design of the full coverage com- ponent all suggest that success is a function of comprehensive treatment planning as much as technical expertise. Evidence-based or controlled best evidence studies should conclude that these are non-endodontic causes of failure and that the success of endodon- tic treatment itself is high and predictable. Kvist and Reit39 have shown that while surgical cases demonstrated higher healing rates than non- surgical retreatment cases initially, four years after treatmenttherewasnodifferencebetweenthetwo modalities, owing to ‘late’ surgical failure. The fail- ure rate for surgical therapy appears to be analo- goustothefailurerateforretreatmentasafunction ofthesizeofthelesiontreated.40 Levelsofapicalre- section41 and the type of root-end filling material make a difference to surgical treatment outcome success;42 however, the dentine-bonded composite technique and the use of compomer materials has not been widely reported on. As these techniques dome the resected root face, sealing off the cut tubules,theymayprovetobethemosteffectiveret- rogradesurgicalprotocolsofall.Theliteratureisun- clear concerning peri-apical re-surgery. Gagliani et al.43 compared peri-apical surgery and re-surgery over a five-year follow-up period. Using magnification and microsurgical root-end preparations,thepositiveoutcomeforprimarysur- gery was 86% and 59% for re-surgery. While oth- ers have shown positive outcomes for re-surgery, the deci-sion remains highly case specific. In spite of our best efforts, negative endodontic treatment outcomes occur and ortho-biological replacement of teeth and their surrounding anchoring struc- tures is an integral part of contemporary founda- tional treatment planning. A recent article by Assuncao et al.44 describes engineering methods used in dentistry to evaluate the biomechanical behaviour of osseointegrated implants. Photoelasticity is used for determining stress-concentration factors in irregular geome- tries.Theapplicationofstrain-gaugemethodology todentalimplantsprovidesbothinvitroandinvivo measurement strains under static and dynamic loads. Finite element analysis can simulate stress using a computer-generated model to calculate stress, strain, and displacement. An analysis of the impact of mechanical/technical risk factors on im- plant-supported reconstructions is beyond the scope of this publication; however, the replace- ment of lost teeth by implants should, without ex- emption, provide a feeling of restitutio ad inte- grum. The means by which the restoration of the original condition at the crown–root interface is idealised is detailed in this article. The structure and composition of teeth is perfectly adapted to the functional demands of the mouth, andaresuperiorincomparisontoanyartificialma- terial.Sofirstofall,donoharm. —Anonymous _Back to the egg An increased uniform amount of coronal den- tine significantly amplifies the fracture resistance of endodontically treated teeth regardless of the post system used or the choice of material for the full coverage restoration.45 A recent article by Coppede et al. demonstrated that friction-locking mechanics and the solid design of internal conical abutments provided greater resistance to defor- mation and fracture under oblique compressive loading when compared to internal hex abut- ments.46 These two ‘seemingly’ disparate observa- tions define the inherent continuum between nat- ural tooth engineering and the principles of engi- neering necessary to ortho-biologically replicating the native state. The use of a ferrule or collet and a bonded or in- timately fitted post-core to restore function and form to an endodontically treated tooth is analo- 12 I implants2_2011 Fig. 8 Fig. 7 Fig. 6