Amir Reza Rokn, DDS, MSc
Mohammad-Sadegh Ahmad-Akhoundi, DDS, MSc.
Shahroo Etemad-Moghadam, DDS, MSc.
Abbas Mirzaei, PhD
Vol 16, No 5 (2019)
Pain is a constant symptom of dentin hypersensitivity (DH), which is a common condition that affects daily life and negatively affects the quality of life (QoL). Diagnosis and outcome measurements following the treatment of the disease require accurate pain assessment. The definition of pain underlies the complexity of its measurement as different factors modulate daily experience. The reproducibility of the prescribed stimuli for inducing DH pain clinically is difficult to achieve. This pain mevaasurement is made with unidimensional scales that are inadequate to capture the other dimensions of pain. The only specific QoL tool available for DH still requires testing in other populations and cultures. This article reviews the appropriateness of the current methods of DH pain assessment and the tools that consider the other pain dimensions. It also looks at its impact on the oral health-related quality of life (OHRQoL) of people with DH. The findings will create interest and facilitate research in this field of DH pain measurement and management.
Objectives: This study aimed to assess the dentin adaptability of a certain type of fluoride varnish, as a novel root canal sealer, in comparison with AH-Plus sealer.
Materials and Methods: Twenty-four extracted single-rooted, single-canal human permanent teeth with straight and fully formed roots and no internal calcification, resorption or cracks, were selected and decoronated such that the remaining root length was 14 mm in all teeth. Root canals were prepared using the Mtwo rotary file system according to the manufacturer's instructions and filled with gutta-percha and either AH-Plus (n=12) or fluoride varnish (n=12) via the lateral compaction technique. Each root was then sectioned at 4 and 8 mm distances from the apex for evaluation under a scanning electron microscope (SEM). The gap size between the sealer and dentin was measured. Statistical analysis was performed using the Kolmogorov-Smirnov test and t-test with the significance level set at 0.05.
Results: The mean gap size was 14.407±1.402 µm and 8.342±0.694 µm in the roots obturated with AH-Plus and fluoride varnish sealers, respectively. The t-test revealed a statistically significant difference (P<0.001) in this regard between the two groups.
Conclusion: Fluoride varnish, as a root canal sealer, has a superior adaptation to dentinal canal walls compared to the AH-Plus sealer.
Objectives: This study aimed to assess the effect of application of two types of zirconia primers on repair bond strength of composite to zirconia ceramic.
Materials and Methods: In this in vitro, experimental study, 60 zirconia blocks were divided into five groups and subjected to the application of Z-Prime Plus (ZPP), Monobond Plus (MBP), Porcelain Bonding Resin (PBR), ZPP followed by PBR (ZPP+PBR) and MBP followed by PBR (MBP+PBR). They were then bonded to Z100 composite. The samples were then immersed in water at 37°C for 24 hours, thermocycled for 1000 cycles between 5-55°C and subjected to shear bond strength (SBS) test. The mode of failure was determined under a stereomicroscope and a scanning electron microscope (SEM).
Results: The mean bond strength was the highest in ZPP+PBR group followed by MBP+PBR, ZPP, PBR and MBP group (22.29±8.86, 15.75±2.81, 12.02±3.24, 3.60±2.92 and 2.92±1.78 MPa, respectively). The effects of type of zirconia primer and use/no use of PBR on SBS were significant (P<0.05). The frequency of adhesive failure in MBP and PBR groups was significantly higher than that in MBP+PBR and ZPP+PBR groups (P<0.05). The cohesive failure was significantly more frequent in ZPP+PBR group than in ZPP, MBP and PBR groups (P<0.05).
Conclusion: Simultaneous application of zirconia primer and PBR is the most efficient technique for repair of all-ceramic zirconia restorations with composite resin.
Objectives: To evaluate the effect of ozone and two common denture cleansers on the surface hardness and bond strength of a silicone-based soft liner to acrylic denture base material.
Materials and Methods: Sixty cylindrical specimens were fabricated using heat-cured poly-methyl methacrylate denture base resin. Three millimeters of the material was ground from the midsection and filled with the soft liner. The resilient liner specimens (n=40) used for the hardness test were 10 mm in diameter and 5 mm in height. Cylindrical and disc-shaped samples were randomly divided into four groups (37°C distilled water, Corega® tablets, 0.5% sodium hypochlorite (NaOCl), and a home ozone generator). To simulate six months of denture cleansing clinically, samples were placed in their cleanser once a day for six months according to the manufacturer’s instructions. All cylindrical specimens were placed under tension until failure in a universal testing machine at a crosshead speed of 5 mm/minute. For disc-shaped samples, hardness was measured using a Shore-A durometer. The results were analyzed using Kruskal-Wallis test, analysis of variance (ANOVA), and Tukey's post hoc test.
Results: The mean tensile bond strength was not significantly different among the studied groups (P>0.05). The mean hardness in the ozone and Corega tablet groups was significantly lower than that of the control and NaOCl groups (P<0.05).
Conclusion: The type of denture cleanser does not affect the tensile bond strength of silicone soft liners. Home ozone generators and cleansing tablets have less effect on the hardness of soft denture liners compared to 0.5% NaOCl.
Objectives: This study aimed to compare the optical properties of Zolid FX, Katana UTML, and lithium disilicate laminate veneers.
Materials and Methods: In this in-vitro experimental study, the maxillary left lateral incisor of a phantom received a laminate veneer preparation. An impression was made, and a die was fabricated using dental stone. The die was scanned using a computer-aided design/computer-aided manufacturing scanner. Ten dies were fabricated from each of the A1, A2, and A3 shades of composite resin. Laminate veneers were fabricated using A1 shade of Katana UTML, Zolid FX, and IPS e.max CAD ceramics (n=10) and placed on composite abutments using bleach and white colors of trial insertion paste (TIP). The optical properties were measured at the incisal, middle, and cervical thirds using a spectrophotometer. Data were analyzed using three-way analysis of variance and Tukey’s test.
Results: The effect of laminate material on the L*, a*, and b* parameters was significant in all areas (P<0.001), except for the L* parameter in the middle and cervical thirds. All color parameters were affected by TIP color in all three regions in most samples (P<0.05). The effect of composite abutment shade was also significant in most cases (P<0.05). The effect of laminate material, abutment shade, and TIP color on the b* parameter was significant (P<0.001). The L* parameter was almost the same in the two zirconia and lithium disilicate ceramic groups.
Conclusion: The composite abutment shade, TIP color, and laminate material should be carefully selected to achieve optimal aesthetics in laminate veneers.
Objectives: This study aimed to assess the shear bond strength (SBS) of molar tubes to the enamel surface of molar teeth using a resin-modified glass ionomer (RMGI) cement modified with amorphous calcium phosphate (ACP).
Materials and Methods: In this in-vitro study, 60 extracted human third molars were randomly divided into four groups for bonding of molar tubes to the enamel surface. Fuji Ortho LC and Fuji Ortho LC modified with ACP (1.55 wt%) were used in groups 1 and 2, respectively. In group 3, the enamel surface was sandblasted, and bonding was then performed using Fuji Ortho LC glass ionomer modified with ACP. In group 4, molar tubes were conventionally bonded using Transbond XT composite. The SBS was measured using a universal testing machine.
Results: The mean SBS of groups 1 to 4 was 10.22, 6.88, 9.4, and 13.68 MPa, respectively. Only the SBS of group 1 was not significantly different from that of groups 3 and 4 (P>0.05). Comparison of adhesive remnant index (ARI) scores of the groups revealed significant differences only between groups 1 and 4 (P<0.001) and between groups 1 and 2 (P=0.002).
Conclusion: The results revealed that the addition of ACP to Fuji Ortho LC significantly decreased the SBS of molar tubes bonded to enamel compared to the conventional resin bonding system. Sandblasting of the enamel surface significantly increased the bond strength. Fuji Ortho LC modified with ACP is recommended for bonding of molar tubes to posterior teeth considering its cariostatic property.
Objectives: We aimed to evaluate the knowledge and attitude of Iranian dentists towards cone-beam computed tomography (CBCT).
Materials and Methods: A 20-item questionnaire was distributed among 410 Iranian dentistry graduates attending the 56th Congress of Iranian Dental Association held in Tehran, Iran. The questionnaire included items on demographic characteristics, namely full name, age, gender, work experience, type of current activity (individual or group), and the highest educational level. In addition, the questionnaire contained items on the knowledge and attitude of dentists. The obtained data were analyzed using statistical tests.
Results: In this study, 49.3% and 22.4% of the subjects were male and female, respectively, 47.1% of whom used CBCT, while 49.8% did not. In detail, 72.2% of the dentists used the technique to evaluate the location of implants, whereas 19.7%, 3.2%, and 2.7% of the subjects applied it to localize the inferior alveolar nerve (IAN), evaluate the location of implants and localize the IAN, and perform cephalometric analysis, respectively. The main causes of lack of prescription of CBCT entailed high cost (80%), high rate of patient absorbed dose (27.6%), insufficient number of CBCT centers (46.3%), and the long duration of the process (15.6%).
Conclusion: CBCT is an advantageous imaging technique in dentistry. Considering the increased application of CBCT in dentistry, attending workshops could help train dentists to use the technique.
Objectives: Considering the emergence of resistant microbes and side effects of chemical drugs, in this study, the inhibitory effect of organic and hydro-alcoholic extracts of Boswellia serrata (B. serrata) on some oral microbiota was investigated.
Materials and Methods: In this experimental study, standard strains of Candida albicans (C. albicans; PTCC 5027), Candida glabrata (C. glabrata; PTCC 5295), Candida krusei (C. krusei; PTCC 5297), and Streptococcus mutans (S. mutans; PTCC 1688) were collected from the Iranian Research Organization for Science and Technology (IROST). Then, the minimum inhibitory concentration (MIC) of organic and hydro-alcoholic extracts of B. serrata was determined based on the CLSI protocol and using the micro-dilution method. The contents of each well were subcultured in Müller-Hinton agar (Candida species) and blood agar (S. mutans). The lowest concentration with no growth was considered as the minimum fungicidal concentration (MFC) or bactericidal concentration (MBC). Statistical analyses were performed using Mann-Whitney test.
Results: Hydro-alcoholic extract of B. serrata at the concentration of 50 mg/ml inhibited the growth of C. albicans and S. mutans. It also inhibited the growth of C. krusei and C. glabrata at the concentration of 100 mg/ml. Organic extract of B. serrata at the concentration of 200 mg/ml only inhibited the growth of C. glabrata.
Conclusion: Hydro-alcoholic extract of B. serrata had a greater inhibitory effect on C. albicans and S. mutans compared to the organic extract.
Objectives: Color change of cements over time can be detected through translucent ceramic veneers, compromising the aesthetic appearance of restorations in the long-term. This study aimed to assess the color stability of ceramic laminate veneers cemented with self-adhesive resin cements after accelerated aging.
Materials and Methods: In this study, 21 IPS e.max ceramic discs, measuring 8mm in diameter and 0.7 mm in thickness, were fabricated and divided into three groups (n=7) for the application of Choice 2 total-etch light-cure resin cement, RelyX U200 dual-cure self-adhesive resin cement, and SpeedCEM self-cure self-adhesive resin cement. The ceramic discs in each group were cemented on the prepared facial surface of bovine teeth. The color parameters were assessed using a spectrophotometer. Subsequently, the samples were subjected to accelerated aging for 100 hours, and the color parameters were measured again. The data were analyzed using two-way repeated-measures analysis of variance (ANOVA) and Tamhane’s post-hoc test (P<0.05).
Results: Aging significantly affected the ceramic laminate color parameters in all three groups (P<0.05). SpeedCEM cement showed the lowest color stability (∆E=4.2) after aging, and its color change was clinically unacceptable (∆E>3.5). The color change of the other two groups was clinically acceptable (1<∆E<3.5).
Conclusion: The self-adhesive dual-cure cement showed color stability comparable to that of the total-etch light-cure cement for cementation of IPS e.max ceramic laminates. The color stability of both cements was superior to that of the self-adhesive self-cure cement.
Induction of premalignant lesions in animal models is of high value for research purposes. This study aimed to induce dysplasia in hamster mucosal pouch for investigation of dysplastic lesions using dimethylbenz(a)anthracene. The buccal pouch of 10 hamsters was painted with dimethylbenz(a)anthracene for 10 weeks every other day. At 5 and 10 weeks, they underwent histopathological analysis. Clinically, there was no change until week 7; after which mucosal thickening occurred. Hamsters scarified at 5 weeks and 10 weeks demonstrated mild and moderate dysplasia, respectively. dimethylbenz(a)anthracene is a useful tool for inducing dysplastic lesions in the buccal pouch mucosa of hamsters.
Amir Reza Rokn, DDS, MSc
Mohammad-Sadegh Ahmad-Akhoundi, DDS, MSc.
Shahroo Etemad-Moghadam, DDS, MSc.
Abbas Mirzaei, PhD
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