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

132I inlays was lower than that for theother types of inlays, that is two-,three- and four-surface inlays.In study of over 1,544 amalgamrestorations, 1,213 restorationsremained after fifteen years. Itappeared as if the three-surfacerestorations had less favourableclinical outcomes compared totwo-surface restorations after 15years. Also, the provision of a 90 ocavosurface angle combined witha cavity wall finish reduced the riskof failure of amalgam restorations,compared to larger cavosurfaceangles 108,109 .Prati et al. 161 reported three-yeardata on 116 Class III and V polyacid-modifiedcomposite resin(‘compomer’) restorations. Theyfound no statistical differences withrespect to the USPHS criteriabetween the Class III and V restorations.In a cross-sectional appraisal of520 cast restorations in 56 patientsmade between one to 40 yearspreviously, the restorations includingmore than two surfaces wereassociated with less favourableoutcomes of quality and survival 162 .The outcome after three yearsof 446 restorations placed byone dentist and two dental nursesin 282 patients using the ARTtechnique was reported byPhantumvanit et al. 148 . The survivalwas lower for occlusal surfacerestorations compared to those inother surfaces.Friedl et al. 163,164 carried out across-sectional study in which 102dentists provided informationabout 3,375 composite resin and5,240 amalgam restorations. Thefailed restorations with foursurfaces had a lower median agecompared to the other types ofrestorations.Jokstad et al. 165 reported on across-sectional study of 8,310restorations a marked associationbetween the age of the restorationsand both the types and the size ofthe restorations.Data from a five-year prospectivestudy of the of 2,399 Class IIIand 1,093 Class V chemically-activatedanterior composite resinrestorations assembled from 26general dental practices indicatedthat the overall probability ofsurvival at five years was 10 percent higher for Class V restorationsthan for Class III restorations 142 .Smales and Gerke 166 evaluated700 anterior composite resinrestorations over four years. Significantlymore failures occurred inClass IV and V preparations. Ofall failures, 81 per cent were fromClass V preparations, which mayreflect undue reliance on dentinebondingsystems for restorationretention in premolar non-cariouscervical lesions.Fritz et al. 167 reported the longtermoutcome of 2,717 castrestorations provided for 548patients during 1960–1989. Relativelyminor differences in the 15year survival were noted for foursizes of casts: single surface (65 percent), two-surface (60 per cent),three-surface (68 per cent) andinlays and onlays (70 per cent).Investigations published before1992 on the association betweenClass I and Class II cavity preparationsfor amalgam and restorationsurvival has been reported in aprevious paper and will not bediscussed further 113 .Wilson and Norman 147 reportedfive-year findings of an 11-centretrial of a posterior composite resin.The findings were based on datacollected from 649 (68 per cent)of the 958 restorations originallyplaced. Chi-square analyses indicatedthat of the independentvariables investigated, size ofrestoration had the greatest associationwith clinical performance.In a study of 950 anteriorcomposite resin restorations oversixteen years there were significantlymore failures with the Class IVcompared to the Class III restorations153 .Bentley and Drake 168 reported astudy of 1,207 restorations placedby students in 70 patients. Singlesurfacerestorations lasted longerthan multi-surface restorations.Moreover, multisurface restorationsincluding the occlusal surfacesurvived significantly longer thandid those including the facial orlingual surface.Material handling andproceduresFactors associated with materialhandling and procedures that mayaffect the incidence of margin failuresof amalgam restorationsinclude trituration time 106 , use ofrubber dam 169,170 , condensationtechniques 171 , and the carving,burnishing and polishing techniques172 . The effect of burnishingamalgam restoration margins isdifficult to estimate, and nearlyimpossible to quantify since the‘surface treatment’ is influenced byfactors such as burnishing load,direction of the strokes, numberof strokes, beginning time aftertrituration and the size of theburnisher 172 .To what extent cavity varnishesand their thicknesses promotemarginal failures is unknown. It isconceivable that some varnishesmay be incorporated into the amalgamalong the margin, and therebyreduce the strength in these areas.Thus, there is a theoretical possibilitythat the type or amount ofvarnish may be related to marginfracture. However, clinical data onsuch a relationship is sparse, andexisting data are not conclusive. Inone longitudinal study it wasrevealed that application of avarnish or silver suspension did notinfluence the risk of long-termrestoration failure 107–109 .Letzel et al. 171 assessed the typeof condensation instrument, togetherwith patient and operator on theperformance of a single amalgamalloy over 2.5 years. The authorsreported an association betweenfailure and the patient and theoperator, but there were too fewfailures to establish an associationwith condensation instrument.However, the authors did not indicatehow ‘failure’ was assessed.International Dental Journal (2001) Vol. 51/No.3