PubMed · 779091
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J O Forsling, F Sundström. 1975-04-01. [Cavity preparation].. https://pubmed.ncbi.nlm.nih.gov/779091/
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OBJECTIVE: The purposes of this study were to investigate cavity surfaces morphologically, and compare microleakage at cavities prepared by Er:YAG laser after composite resin restoration versus conventional mechanical treatment in human primary teeth in vitro. BACKGROUND DATA: There have been few reports on microleakage at cavities prepared by Er:YAG laser irradiation. MATERIALS AND METHODS: A total of 30 cavities (class V) in human primary teeth were used. Half of the cavities were prepared by an Er:YAG laser system at 300 mJ pulse energy and 4 Hz, and the other half were prepared with a high-speed diamond bur. Five cavities from each group were investigated by scanning electron microscopy (SEM) and histopathological examination. Remaining cavities were filled with a composite resin without an acid-etching technique and then subjected to microleakage test in 0.6% rhodamine B solution under thermocycling. RESULTS: Microleakage (score: 2.45 +/- 1.07) at cavities prepared by laser was significantly less than that by bur (score: 1.30 +/- 0.95; p < 0.05). SEM observation showed that, compared with the relatively flat appearance of cavities prepared by bur, cavity margins prepared by laser were irregular but there was almost no smear layer at the cavity walls. CONCLUSION: It can be concluded that cavity surfaces prepared by Er:YAG laser are irregular, but microleakage at cavities prepared by the laser after filling with composite resin is better than that by mechanical bur using the dye penetration method.
OBJECTIVE: The purpose of this study was to use scanning electron microscopy (SEM) in order to compare the surfaces of cavities prepared using laser with those prepared conventionally, and to measure the degree of leakage through both enamel and cementum. MATERIALS AND METHODS: We prepared 135 class V cavities and divided them randomly into three groups: laser-treated (group A), laser-treated, and acid-etched (group B) and rotary instrumented (group C). RESULTS: On analyzing the tooth enamel, the amount of leakage was found to be similar in groups A and B, whilst the samples in the group C were more prone to leakage. On analyzing the cementum, the group C samples appeared to display surfaces that were more conducive to the adhesion of the materials used in obturation (although this difference was not strictly significant), and this might have provoked the relatively low levels of leakage. CONCLUSION: The use of acid etching in conjunction with both conventional and laser cavity preparation improves the adhesion of the materials used in obturation to enamel surfaces.
This study is an attempt to intervene in the contemporary debate on the interpretation of Greene V. Black's well known principle of "extension for prevention." It is possible to discern two, divergent strains within Black's thought: he contends that his principle should have universal application, at the same time as he seeks to limit its application. The conflict between these two positions may be resolved by arguing that Black's comments are directed at different audiences: Black does not actually believe that extension for prevention should be universally applied, but reserves the judgment not to extend to only the most experienced operators. The remainder, the majority of operators, should behave as if it were a universal principle.