Journal of Dental Medicine

Statement of Problem: Bleaching materials are able to change the surface morphology as well as mineral and organic content of tooth structure. Considering that bleaching is done for aesthetic purpose, awareness of the possible effect of these materials on hard tissue is important, because it may affect the restorative treatments.

Purpose: The aim of this study was comparing the effect of two bleaching materials, Kimia and Ultradent both containing 35% H2O2, on tooth enamel by SEM.

Materials and Methods: Five intact central incisors were cut into three sections vertically and each part was randomly divided into three groups. Group 1 (control), without any bleaching. Group 2, bleached with Kimia 35% H2O2. Group 3, bleached with Ultradent 35% H2O2. Each tooth served as its own control. Then the samples were observed by SEM with 250 and 500 magnifications.

Results: In the control group some scratches and small white grains were observed which seems to be the result of mastication trauma and pumice powder. In the other groups, morphologic changes like increased surface roughness, deepening of cracks, rod exposure and presence of new cracks were observed. The two experimental materials did not differ in these regards.

Conclusion: It seems that both studied materials have limited destructive effects on tooth enamel which seems to be of no clinical importance.

Background and Aim: Microscopic differentiation between well differentiated squamous cell carcinoma and verrucous carcinoma is very difficult. As these lesions have different clinical course and treatment a reliable method to help distinguish between them is necessary. The basement membrane in oral verrucous carcinoma is generally intact whereas in oral squamous cell carcinoma is mostly discontinuous. This structure can be studied by different methods. The aim of this study was to differentiate these lesions with special staining of basement membrane.

Materials and Methods: In this tests evaluation study, a total of 26 cases consisting of 15 oral squamous cell carcinomas and 11 oral verrucous carcinomas were retrieved from Cancer Institute of Imam Khomeini hospital archive of pathology and their paraffin blocks were cut and stained with Periodic Acid Schiff method. Slides were studied with light microscope to evaluate the continuity of basement membrane. Sensitivity and specificity of this method were calculated.

Results: The sensitivity of this method for differentiating oral squamous cell carcinoma from oral verrucous carcinoma was 100% whereas the specificity was 90.9%. Positive predictive value was 93.75% and negative predictive value 100%.

Conclusion: Based on the results of this study, the sensitivity of this test for diagnosis of oral squamous cell carcinoma was high (100%). Further studies are needed to evaluate the use this method for distinguishing oral verrucous carcinoma from oral squamous cell carcinoma.

Background and Aim: Several surgical approaches have been used to achieve root coverage. The Subepithelial Connective Tissue Graft (SCTG) procedure has been shown to be a predictable means to treat gingival recession. Semilunar Coronally Positioned Flap (SCPF) is a simple mucogingival surgery to cover the exposed root surface without harvesting the palatal connective tissue. The purpose of this study is to compare the outcome of gingival recession therapy using SCTG and SCPF.

Materials and Methods: Forty Miller class I buccal gingival recessions (≥2mm) were selected. Recessions were randomly assigned to receive either the SCPF or SCTG. Recession Height (RH), Recession Width (RW), Width of Keratinized Tissue (WKT), Probing Depth (PD), Clinical Attachment Level (CAL), were measured at baseline, 1, 3, and 6 months after surgery. The data were analyzed using independent t-test and Repeated Measure ANOVA.

Results: The average percentages of root coverage for SCPF and SCTG were 88% and 71%, respectively and the complete root coverage observed were 55% and 45%, respectively. There were no significance differences between the two groups with regard to RW, PD, CAL, WKT (except in the third month after surgery which was slightly greater in SCPF group). RH was significantly decreased from 2 to 6 months after surgery in SCPF group.

Conclusion: The findings from this study indicate that if the tissue thickness and initial width of keratinized tissue are sufficient, SCPF may be a good substitute for SCTG in treatment of Miller class I gingival recessions.

Background and Aims: The aim of this study was to evaluate the quality of an experimental hydrofluoric acid (HF) for preparation of porcelain and to compare it with two commercial hydrofluoric acids in Iranian trademark.

Materials and Methods: A- Evaluation of etch pattern of experimental HF using scanning electron microscope (SEM): 6 feldespathic discs were divided into 3 groups. Each group was etched with related HF (experimental, Ultradent and Kimia) for 1 minute. SEM images were recorded at 3 magnifications. B- Bond strength test: 18 feldespathic discs were considered for each acidic group. Then the porcelain surfaces were etched and bonded to composite with unfilled resin. Consequently, the microshear test was done. C- Microleakage test: 54 discs were divided into 3 groups (n=18). Then the porcelain surfaces were etched and bonded to composite with unfilled resin and finally observed under stereomicroscope. The data were analyzed with one-way ANOVA and Smirnov tests.

Results: SEM analysis showed no difference between groups in terms of etch pattern. Microshear bond strength values for experimental, Kimia, and Ultradent HF were 28.53 (±4.92), 28.21 (±6.61), and 26.14 (±7.61) MPa, respectively. There was no significant difference between the bond strength of test groups (P<0.05). Furthermore, no significant difference was found between the microleakage of test groups (P>0.05).

Conclusion: Quality of experimental HF in terms of etch pattern, microshear bond strength and microleakage of composite/porcelain interface was similar to that of two commercial hydrofluoric acids.