StomatologyEduJournal1-2015 | Page 16

RESTORATIVE DENTISTRY Table 7 Relationship between success rate, incidence of failures, partial loss or chipping and the use of dental dam or tooth vitality Total restorations Integral (code 0) Chipped (codes 1, 2) Partial Lost (codes 3, 4) Failures (code > 5) Yes 118 91 16 2 9 No 186 151 20 2 13 Yes 181 144 22 3 12 No 123 98 14 1 10 Dental dam Tooth vitality Discussion Glassionomer cements underwent deep changes in recent years. The materials have evolved, and the severe limitations that characterized the GICs in the 80s have been exceeded. In this clinical trial, the high percentage of success in class I restorations (close to 100%), together with the easy and quick procedure identified by the followed protocol, identified a high viscosity glassionomer cement as a possible and durable choice for this kind of restorations both in molars and premolars. The possibility of achieving durable Class II restorations with the glassionomer-based restorative system tested in this trial seems to be related to the width of the mesial or distal box. According to some clinical indications, the width of the box should not exceed the half of the intercuspal distance. Many chippings and some failures of the Class II restorations performed during this trial were located in the marginal proximal crest, in wider restorations. Furthermore, there was a tendency in Class II restorations performed in premolar teeth of a higher failure rate occurring with higher number of restoration surfaces. Class V restorations revealed the lowest survival rate in time, suggesting that in this kind of restoration the performances of the tested GIC system were most challenged. Chemical resistance and selfadhesion define glassionomer cement as reliable material for Class V restorations (25), right where many traditional composite restorations with adhesive systems have high percentages of failure rate. Further prospective trials may be performed to compare the failure rate of a high-viscosity GIC with conventional resin-based composites. The 48-months observations were often accompanied by a certain wear of the restoration, visible with magnifying glasses and which became clinically evident with the loss of translucency. Most of the restorations which developed roughness over time were class V restorations. In the present study, the perception of roughness could probably be related to higher exposure of cervical areas to progressive erosion, caused by daily acidic attack, chewing, tooth brushing, effect of professional 16 mechanical cleaning and, especially in lower incisors and cuspids, progressive deposition of tartar. In occlusal areas, the continuing wearing effect as a consequence of chewing may lead to regular abrasion and to the formation of smoother surfaces than in non-occlusal areas as those where class V restorations are performed. This may explain why the majority of patients referred to roughness on restorations done in cervical areas. Interestingly, the increase in roughness perception seems to occur mainly between the first and the second year after placement. It is still unclear if coating agent should be reapplied or not, to increase the external wear-resistant layer, or if its strengthening and protective role remains unaltered, even if the layer appears modified or reduced. Patients declaring daily consumption of chewinggums were excluded from this study, and consumption of chewing-gums, and their brands and frequency of assumption were checked at each follow-up. It was claimed, indeed, that gum chewing may have an abrasive effect on softened tooth structure (26). Since no data are available upon the abrasive effect of gum chewing on permanent GIC restorations, this parameter was excluded from the present study. The use of dental dam is currently the most effective way to provide isolation of the operative field. It is always recommended for composite restorations placement, since it allows an optimal control of oral fluids and avoids contamination of the cavity and the material during placement procedures. In the present trial, each trained operator was instructed to try and position the dental dam prior to restorative procedures and according to the protocol. If, for any reason, it was not possible to isolate the field using a dental dam, the restoration was placed without this type of isolation. GICs are indeed known to tolerate humidity when used in wet areas (1,13) and therefore do not necessarily require the use of dental dam. In fact, it is not always possible to work under ideal conditions: not all patients tolerate the use of dental dam, like children or psychologically vulnerable individuals where is often impractical the application of this device. STOMA.EDUJ (2015) 2 (1)