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Microleakage of composite resin restorations
Article in Australian Dental Journal · January 2009
DOI: 10.1111/j.1834-7819.2008.00084_1.x · Source: PubMed
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Nidambur Vasudev Ballal
Manipal University
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Australian Dental Journal2008; 53: 369–370 doi: 10.1111/j.1834-7819.2008.00084.xª2008 Australian Dental Association 369
MICROLEAKAGE OF
COMPOSITE RESIN
RESTORATIONS
I read with great interest the article entitled ‘Microleakage of composite resin restorations in cervical cavities prepared by Er,Cr:YSGG laser radiation’ by S Shahabi et al. which has been published in your esteemed jour-nal (Aust Dent J 2008;53:172– 175). I want to share a few of my thoughts regarding this study. It was an interesting study, but the authors can redefine the study by incorporating a few of the following criteria. First, teeth with class V cavities which have been restored with composite resin can be subjected to occlusal loading. It has been proved that teeth are subjected to heavy occlusal stresses during normal function and parafunction. These occlusal stresses cause the tooth to flex. As the tooth flexes, tensile and shear stresses are generated in the cervical region of the tooth.1 This stress may cause debonding of composite resin from the cavity margins and thereby increase microleakage. Second, instead of methylene blue dye, 2% Rhodamine B dye can be used. It presents greater diffusion on the human tooth than methylene blue dye.2 Also, the molecules of Rhodamine B dye are small and nanometric and are optimal to stimulate enzymes and toxins of leakage resulting from bacterial metabolism.3 Dye leak-age can be conducted under vacuum pressure, since the valid-ity of dye leakage studies has been questioned because of the
possible effect of entrapped air on the ingress of the dye solu-tion.4 Studies have reported that vacuum pressure decreases the volume of entrapped air and allows complete dye penetration.5 Also, the authors in this study have not mentioned which type of curing light was used, since the type of curing light accounts for the degree of polymerization shrinkage of composite resin which in turn affects the micro-leakage. The sectioning of the tooth in this study was done mesiodistally. How is it possible to visualize the cavity mar-gins⁄walls, when the cavity was
prepared on buccal or lingual surface and sectioning is done mesiodistally?
REFERENCES
1. Rees JS. The effect of variation in the occlusal loading on the development of abfraction lesions: a finite element study. J Oral Rehab 2002;29:188– 193.
2. Grempel M, Antoniazzi JH, Paiva JG. [Determination of the root dentine permeability of natural human teeth earlier, according to age and type of dye used.] Rev Paul Odontol 1990;12: 4–14.
3. Francci CE. Early microleakage in combined silver amalgam⁄composite
resin restoration in posterior teeth: an in vivo study. Sao Paulo, SP, Brazil: University of Sao Paulo, 1995 (in Portuguese). Thesis.
4. Spradling PM, Senia S. The relative sealing ability of paste type filling materials. J Endod 1982;8:543–549. 5. Oliver CM, Abbott PV. Entrapped air
and its effect on dye penetration of voids. Endod Dent Traumatol 1991;7: 135–138.
N VASUDEV BALLAL Karnataka, India
(Received 22 July 2008.)
MICROLEAKAGE OF
COMPOSITE RESIN
RESTORATIONS:
AUTHORS’ REPLY
We thank Dr Ballal for his detailed comments on our recent paper in the Journal. The intention of the study was to assess differences in microleakage between laser etch-ing and conventional treatments, and to that end we deliberately minimized as many extraneous variables as possible from the experimental design. We agree that there are a number of poten-tial shear forces which can devel-op in the cervical region, and this was one of the reasons why we placed the inferior margin of the test cavity in cementum and the superior margin in enamel. We have previously investigated laser etching of tooth structure in great detail,1–3and in those studies we have examined shear forces as well as other variables which can affect the result obtained with laser conditioning. It would be interesting to examine the effects of occlusal loading on leakage as a purely mechanical effect, how-ever this is difficult to reproduce on actual teeth, and for the current study we were more interested in the well known variable of thermo-cycling as a reproducible and stringent factor related to micro-leakage.
In relation to the second point Dr Ballal raises, which is the use of various tracer dyes, there is a broad range of suitable agents which can be used, and we have used various agents in the past in our dental materials research. There is no one ideal dye to Letters may comment on articles published in the Journal and should offer constructive criticism. When appropriate, comment on the letter is sought from the author. Letters to the Editor may also address any aspect of the profession, including education, new modes of practice and concepts of disease and its management. Letters should be brief (no more than two A4 pages).
