Quality of dental restorations. FDI Commission Pro... - ResearchGate

138study of initially 158 fixed prosthesesmade by senior dental students25 years previously. The resultsindicated that the frequency of pulpdeterioration in association withbridges tends to be related to thesize of the prosthesis. It can bespeculated that this can be theeffect of biomechanical complexity,including factors such as acomplex alignment of preparationswith possible iatrogenic tissueremoval and overtapered abutments;lack of acceptable fit in partsof the casting; tendency to acceptsmall discrepancies in large, fixedprostheses compared to singlecrowns, and the complications oforal hygiene procedures.Periapical complications andvertical root fractures following theplacement of restorations orcrowns with pulpal or parapulpalposts may be considered as iatrogenic.Cross-sectional studies indicatethat this is perhaps morecommon than is acceptable. Grieveand McAndrew 204 examined radiographically327 post-retained crownsfor length of post, length ofremaining root filling, periapicalcondition, fit and angulation ofthe post and quality of root filling.Most root fillings were judged tobe unsatisfactory, and there wasno radiographic evidence of anyroot filling in nearly 10 per cent ofcases.Investigations published before1992 on the possible relationshipbetween Class I and Class II cavitypreparations for amalgam andadverse effects on the pulp hasbeen reported in a previous paper,and will not be discussed further 113 .Material handling andproceduresThe principles for prevention ofpulpal damage during preparationwith rotating instruments wereoutlined many years ago, and arestill valid today. Key factors arefrictional heat and adequate cooling,excessive dehydration and airblast, and vibration and highspeed 46 .Concerns over possiblemicroleakage and postoperativesensitivity with amalgam restorationshave led many practitionersto use various varnishes and resincontaininglining, or ‘adhesive’materials. However, others havequestioned the merit of amalgambonding, and the results areconflicting 205 .Cases of persistent post-operativesensitivity with composite resinrestorations following total etchingand application of some dentineadhesives have been reported. Thisclinical phenomenon can occurdespite careful isolation prior todirect restorative procedures andthe use of an incremental build uptechnique, as well as after cementationof indirect restorations inconjunction with using a compositeresin cement. Problems regardingpost-operative sensitivity are hypothesisedto be related to a deficientlight-curing source, or incompleteevaporation of the primer solventsprior to application of the bondingagent. Alternative suggestions aregaps, cracks in enamel related topolymerisation stresses, fracture oftooth substance at the restorationcavity interface and polymerisationshrinkage followed by hydraulicforces induced during masticationon the dentinal tubule fluid followingflexure of the restoration 195,206 .Patient factorsIntraoral locationIn a study of 88 composite resinrestorations over two years it wasobserved that the postoperativesymptoms were significantly lowerin premolars compared to molars 101 .Borgmeijer et al. 196 reported postoperativesensitivity after placing244 Class II restorations ofcomposite resin and amalgam. Postoperativesensitivity occurred moreoften in the molars than in thepremolars although the differencewas not statistically significant. Theresearch group reported that thisfinding had also been observed inanother study of 240 indirect ClassII composite resin inlays and amalgamrestorations 207 .Age and genderDuring function, secondary andreparative dentine is deposited inthe pulp. At age 55 years, thevolume of the pulp is about 20 percent of that at age 25, and containsonly 20 per cent of the bloodsupply 208 . This suggests that thepulp’s capacity of recovery decreaseswith age. However, there are nodata in the literature reporting theincidence of endodontic complicationsas a function of patient agefollowing restorative therapy.Oral environmentAnecdotal observations suggest thatbruxism may be associated with anincreased risk of pulpal complicationsfollowing flexing of therestorations and gap formation.The clinical evidence for this is poor.In one early in vitro study it wasdemonstrated that composite resinrestorations placed in third molarsexhibited increased microleakagewhen an antagonist was presentcompared to none 209 . The authorconcluded that bacterial leakagearound restorations in cavitiessurrounded by enamel would mostoften be the result of stress in therestored tooth during occlusion andarticulation. The study has not beenduplicated using modern dentinebonding systems, so it is uncertainto what extent the conclusion isapplicable to newer composite resinmaterials.Does technical excellencepredict failure?A clear relationship between endodonticcomplications and criteriafor technical excellence of dentalrestorations has not been demonstrated.Several review papers havesuggested that such a relationshipexists, but this is substantiatedmostly with laboratory andmicroleakage studies 210 . In one clinicalstudy the radiographic qualityof the root filling and the appearanceof the apical one-third ofInternational Dental Journal (2001) Vol. 51/No.3