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

128cement, composite resin/resinmodifiedglass-ionomer cementand resin-modified glass-ionomercement/glass-ionomer cement.Several studies have reportedcomparisons between ‘sandwich’versus homogeneous restorations,but the conclusions are conflicting.Patient factorsEmpirical observations indicate thatnot only surface, but also bulk andmarginal discolouration vary amongpatients. However, very few studieshave identified specific patientfactors that may influence the opticalcharacteristics of restorations.Marginal discolouration alongveneers made from compositeresin on 87 maxillary anteriorteeth in 23 young patients wasmore common among smokerscompared to non-smokers in alongitudinal study over five years 102 .In a study of 52 pairs of ClassIII microfilled composite resinrestorations after eleven years,surface discolouration was mostoften recorded among smokers,and significant correlations werefound between the patients’consumption of alcoholic beveragesand body and surfacediscolouration 88 .AdaptationTraditionally, the terms used todescribe adaptation have variedwith the examination method, thetype of restoration and the natureof the restorative material. Horizontaldiscrepancies on smooth andapproximal surfaces have oftenbeen termed ‘overhangs’, while theterm ‘marginal ditching’ has beenused to describe defects alongmargins on the occlusal surfaces ofteeth containing mainly amalgamrestorations. The terms over- andunder-extension, with additionaldescriptors of the cement marginmorphology, for example ‘marginalwear’ and ‘cement excess’, haveusually described the adaptation ofindirect restorations. Finally, theterm ‘gap’ has also been used formany years to infer a lack of adaptationbetween the materials andtooth tissues. However, this term israther ill defined and non-specific.Discrepancies measured alonga horizontal or a vertical axistangential to the interface haveoccasionally been interpreted assynonymous to marginal adaptation.Such discrepancies can beassessed clinically, but will necessarilyonly express the adaptationalong the margin on the toothsurfaces. Several methods havebeen used to assess adaptation ofthe entire restoration-tooth interface,but all these methods aredestructive 103 .The clinical evaluation of marginaldiscrepancies is questionable,explained by a lack of reliablediagnostic skills of clinicians. It hastherefore been argued that thescientific community must acceptthat dental restorative materials willbe misjudged during the processof evaluating the marginal qualitiesof restorations 104 .Material factorsThe dental literature containsnumerous papers in whichmarginal degradation has beenevaluated as a function of materialcomposition. The prevailing materialin these studies has been amalgam,and there is consensus that highcopperalloys are clinically superiorto low-copper alloys 105 .Inter-group differences in respectof the marginal degradation ofamalgam restorations often appearafter a short time, and remainconstant 29,69,106–109 . This signifies thatat least one process that results inmarginal fractures occurs duringthe first year after placement ofthe restoration. This hypothesis,however, does not identify orexclude other aetiological factorsthat may be associated withmarginal fractures, including creep,mercuroscopic expansion, biomechanicalrelationships, bulk andcrevice corrosion or fatigue rupture.There may also be differencesbetween composite resins, Bryantet al. 110 having reported thatparticular types of marginal defectsare commonly associated withspecific types of composite resins.In general, restorations of microfilledcomposite resins show moremarginal degradation compared torestorations of other types ofcomposite resins.Operator factorsJokstad 29 reported an influence ofthe operator on the performanceof 468 amalgam restorations offive alloys placed in 210 patientsafter five years. The five dentistswere all able to obtain superiormarginal adaptation with the bestalloys, and contrary to the findingsof Mahler and Marantz 21 , all fivealloys performed equally well forthe five operators. Further, it wasevident that one operator alsoobtained satisfactory marginaladaptation with a low-copperalloy. It was concluded that themain operator variables influencingthe marginal adaptation werethe final condensation of the amalgamand the treatment of thesurface and margins.Mahler and Marantz 21 reportedon restorations of four amalgamalloys placed by four operators.The amalgams were chosen on thebasis of their marginal fracturebehaviour as found in an earlierstudy, ranging from little to extensivefracture. Following placementof the restorations, three-yearevaluation of marginal fracture wasundertaken using a linear ratingscale. It was found that the operatorinfluenced the marginal fractureindex, but in different waysdepending on the alloy. For thealloys with the most and leastmarginal fracture, there was nooperator difference. However, forthe two intermediate alloys, therewere large differences among theoperators. Overall, the associationwith alloy was stronger than withoperator, and it was thereforeInternational Dental Journal (2001) Vol. 51/No.3