Effect of Erbium:Yttrium-Aluminum-Garnet Laser Combined with Mineralizing Agents on Microhardness of Demineralized Dentin

Objective The aim of this study was to assess the combined effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser and mineralizing agents including casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride in improving the resistance of demineralized dentin at new demineralization process.

Materials and Methods One hundred and twenty healthy dentin surfaces were prepared and demineralized using acidic solutions. Primary microhardness was measured (h1), and samples were randomly divided into six groups. Each group received a different protocol as follows: Group A (control group): no additional treatment, Group B: applying a fluoridated gel, Group C: applying a CPP-ACP-containing cream, Group D: irradiation of Er:YAG laser, Group E: irradiation of Er:YAG laser combined with the application of a fluoridated agent, and Group F: irradiation of Er:YAG laser combined with the application of CPP-ACP-containing cream. Microhardness values were measured afterward (h2). Then, all the groups were re-exposed to acidic solution, and microhardness was measured for the third time (h3). The microhardness data were analyzed using analysis of variance and Scheffe's post hoc test.

Results Although application of mineralizing agents increased the microhardness of demineralized dentin in comparison with the control group, no significant difference was observed using two agents. Comparison of laser groups showed an increase in microhardness only after the irradiation of Er:YAG laser combined with the application of a fluoridated agent. Demineralizing process reduced the microhardness values in all the groups, but the application of a CPP-ACP agent caused the least reduction among the laser irradiated groups. Comparison of hardness changes at the beginning and end of the experiment did not show any significant differences between the groups.

Conclusion Comparison of treatment modalities used in this study exhibited that fluoride had the greatest impact on dentin resistance. Laser irradiation on demineralized dentin did not increase the hardness or resistance to acidic attacks.

Comparative Evaluation of the Biochemical Effects of Ketamine plus Ketoprofen and Midazolam in the Premedication of Pigeons

The present study was conducted with the aim of comparing the effects of premedication with ketoprofen and midazolam in birds. A total of 24 male pigeons with an approximate weight of 300 g were divided into four equal groups. The control group (Group I) was injected with ketamine alone. Groups II-IV were injected with ketoprofen alone, ketoprofen+ketamine, and midazolam+ketamine, respectively. The biochemical changes in the four groups were evaluated after intramuscular drug injections at different anesthetic levels. A record of biochemical changes was maintained for each group. Blood samples were taken before and after the administration of the medications in order to measure the levels of serum alkaline phosphatase (ALP), oxaloacetate transaminase (OT), prothrombin time (PT), glucose (GLU), lactate dehydrogenase (LDH), albumin (Alb), total protein (TP), and gamma-glutamyl transferase (GGTF). The results showed significant differences in the mean levels of ALP, OT, PT, GLU, LDH, Alb, and TP after anesthesia, compared to that before anesthesia. Therefore, ketoprofen+ketamine can be used for the induction of anesthesia in birds.The present study was conducted with the aim of comparing the effects of premedication with ketoprofen and midazolam in birds. A total of 24 male pigeons with an approximate weight of 300 g were divided into four equal groups. The control group (Group I) was injected with ketamine alone. Groups II-IV were injected with ketoprofen alone, ketoprofen+ketamine, and midazolam+ketamine, respectively. The biochemical changes in the four groups were evaluated after intramuscular drug injections at different anesthetic levels. A record of biochemical changes was maintained for each group. Blood samples were taken before and after the administration of the medications in order to measure the levels of serum alkaline phosphatase (ALP), oxaloacetate transaminase (OT), prothrombin time (PT), glucose (GLU), lactate dehydrogenase (LDH), albumin (Alb), total protein (TP), and gamma-glutamyl transferase (GGTF). The results showed significant differences in the mean levels of ALP, OT, PT, GLU, LDH, Alb, and TP after anesthesia, compared to that before anesthesia. Therefore, ketoprofen+ketamine can be used for the induction of anesthesia in birds.

Comparing the effect of a desensitizing material and a self-etch adhesive on dentin sensitivity after periodontal surgery: a randomized clinical trial

Objectives

This double-blind randomized placebo-controlled clinical trial evaluated the ability of a desensitizing agent and a self-etch adhesive on cervical dentin sensitivity (CDS) after periodontal surgery.

Materials and Methods

Ninety hypersensitive teeth of 13 subjects were included in the study. After periodontal surgery, the teeth of each posterior sextant treated with one of the following materials: G1: Clearfil S³ Bond (Kuraray Dental), G2: Gluma Desensitizer (Heraeus Kulzer), and G3: placebo (water). The sensitivity was assessed using evaporative stimuli before treatment (baseline, T0), 1 day after treatment (T1), after 1 week (T2), and after 1 month (T3) according to visual analog scale (VAS).

Results

Following the treatment, all the 3 groups showed significant reduction of CDS in T1 compared to T0. Reduction of CDS between T1 and T2 was observed only in G1 but there was no significant difference between T2 and T3 in this group. Although we observed a significant difference in T3 compared to T1 and T2 in G2 and G3, comparison of treatment groups in each assessment time showed a significant difference only in T3. According to paired comparison, this was due to the difference between G2 and G3.

Conclusions

Dentin sensitivity following periodontal surgery will decrease spontaneously over time, but treating the sensitive teeth with Gluma Desensitizer and Clearfil S³ Bond can have some benefits.

Evaluating the shear bond strength of enamel and dentin with or without etching: A comparative study between dimethacrylate-based and silorane-based adhesives

BACKGROUND

Silorane-based composites and their specific self-etch adhesive were introduced to conquest the polymerization shrinkage of methacrylate-based composites. It has been shown that additional etching of enamel and dentin can improve the bond strength of self-etch methacrylate-based adhesives but this claim is not apparent about silorane-based adhesives. Our objective was to compare the shear bond strength (SBS) of enamel and dentin between silorane-based adhesive resin and a methacrylate-based resin with or without additional etching.

MATERIAL AND METHODS

40 sound human premolars were prepared and divided into two groups: 1- Filtek P60 composite and Clearfil SE Bond adhesive; 2- Filtek P90 composite and Silorane adhesive. Each group divided into two subgroups: with or without additional etching. For additional etching, 37% acid phosphoric was applied before bonding procedure. A cylinder of the composite was bonded to the surface. After 24 hours storage and 500 thermo cycling between 5-55°C, shear bond strength was assessed with the cross head speed of 0.5 mm/min. Then, bonded surfaces were observed under stereomicroscope to determine the failure mode. Data were analyzed with two-way ANOVA and Fischer exact test.

RESULTS

Shear bond strength of Filtek P60 composite was significantly higher than Filtek P90 composite both in enamel and dentin surfaces (P<0.05). However, additional etching had no significant effect on shear bond strength in enamel or dentin for each of the composites (P>0.05). There was no interaction between composite type and additional etching (P>0.05). Failure pattern was mainly adhesive and no significant correlation was found between failure and composite type or additional etching (P>0.05).

CONCLUSIONS

Shear bond strength of methacrylate-based composite was significantly higher than silorane-based composite both in enamel and dentin surfaces and additional etching had no significant effect on shear bond strength in enamel or dentin for each of the composites. The mode of failure had no meaningful relation to the type of composite and etching factor.

KEY WORDS

Shear bond strength, adhesive, composite resin, silorane, methacrylate.

Efficacy of four lining materials in sandwich technique to reduce microleakage in class II composite resin restorations

OBJECTIVES

The aim of the present study was to evaluate the effect of four different sandwich techniques on gingival microleakage of Class II direct composite resin restorations.

MATERIALS AND METHODS

Fifty sound human premolars were selected and randomly divided into five groups (n=10). Class II box only cavities were prepared in one of the proximal surfaces of each tooth with a gingival margin located approximately 0.5 mm below the cemento-enamel junction. Group A (control) was restored incrementally with composite resin (Tetric Ceram). Groups B, C, D, and E were restored with the sandwich technique using a compomer (Compoglass F), flowable composite resin (Tetric Flow), self-cure composite resin (Degufill SC), or resin modified glass ionomer (Fuji II LC), respectively. After thermal-load cycling, the specimens were immersed in 0.5% basic fuschin for 24 hours. Dye penetration (10(-1) mm) was detected using a sectioning technique. Data were analyzed with repeated measurements and Duncan test at α=0.05.

RESULTS

The least amount of microleakage was detected in the incremental group (1.28 ± 0.98). The sandwich technique using resin modified glass ionomer (7.99 ± 9.57) or compomer (4.36 ± 1.78) resulted in significantly more leakage than did the sandwich technique using flowable (1.50 ± 1.97) or self-cure composite (2.26 ± 1.52).

CONCLUSION

According to the results of this study, none of the four sandwich technique composite resin restorations used in this study could reduce gingival microleakage to a greater degree than the incremental technique.

Randomized clinical evaluation of the effect of chlorhexidine on postoperative sensitivity of posterior composite resin restorations

OBJECTIVES

Evaluation of postoperative sensitivity in posterior teeth restored with etchand- rinse adhesive and composite resin after application of 2% chlorhexidine solution.

METHOD AND MATERIALS

Thirty participants with similar dental caries on both sides of the jaws were selected. After cavity preparation, each tooth was randomized to one of the following restoration methods. Teeth in the control group were restored using etch-and-rinse resin adhesive (Single Bond, 3M ESPE) and universal microhybrid composite resin (Filtek Z250, 3M ESPE). Restoration of teeth in the experimental group was similar to the control group except that 2% chlorhexidine solution (Concepsis, Ultradent) was applied on the etched dentin for 60 seconds. Subjects were recalled for evaluation of postoperative sensitivity at 1 day, 1 week, 1 month, and 6 months. Data were analyzed by Fisher exact test (α = .05).

RESULTS

The experimental group showed significantly less postoperative sensitivity (8 teeth) compared with the control group (20 teeth) at the 1-day recall (P < .05; Fisher exact test). Conventional restorations were comparable to teeth treated with chlorhexidine at other recall times (P > .05).

CONCLUSION

Chlorhexidine significantly decreased immediate postoperative sensitivity of posterior teeth restored by composite resin.

The effect of bleaching on toothbrush abrasion of resin composites

AIM

This experimental study was designed to focus on the effects of bleaching on toothbrush abrasion in three types of composites with different filler size.

MATERIALS AND METHODS

Forty eight disks were prepared from three types of composite and divided into 6 groups. In the first three groups the abrasion test was done. The remaining groups were bleached and the abrasion test was performed. The weight of the samples before and after abrasion was measured. Statistical analysis was done with one-way ANOVA and Duncan test.

RESULTS

There was a significant difference in abrasion of composites with different filler size (P < 0.05). The most amount of abrasion was observed in Z100 after being bleached. An increase in abrasion was noticed in all three types of tested composite after bleaching.

CONCLUSION

According to the findings, it is suggested to use a nano filled resin composite for restoration if the bleaching treatment is required.

Energy dispersive x-ray analysis of corrosion products in nondiscolored dentin and a dye-extraction study of Class 2 composite restorations following amalgam removal

OBJECTIVE

To evaluate the effect of corrosion products on the microleakage of composite placed adjacent to nondiscolored dentin after amalgam removal.

METHOD AND MATERIALS

Sixty Class 2 cavities were prepared on extracted premolars, which were divided into four equal groups according to the manner in which they were restored: group 1, light-cured packable composite (Elite LS) to establish a microleakage baseline; group 2, a high-copper amalgam (World Work) previously stored in 37°C normal saline for 6 months to create amalgam corrosion products; group 3, identical to group 2, but the amalgam was later replaced with composite, leaving the cavity walls intact; and group 4, identical to group 3 except the cavity walls were extended 0.5 mm after amalgam removal prior to insertion of the composite. Groups 1, 3, and 4 were kept in a 37°C normal saline for 1 week. Ten specimens from each of these three groups were randomly selected for dye-extraction testing, while dentin elemental microanalysis of five specimens from all four experimental groups was also conducted. Data were analyzed using ANOVA and the Tukey tests (α = .05).

RESULTS

Corrosion products were not detected in group 4, and no statistically significant difference (P > .05) in microleakage was found between this group and group 1. The highest dye absorbance was associated with group 3 (P < .05).

CONCLUSION

After amalgam removal, a 0.5-mm extension of the cavity walls could improve the dentinal marginal seal to replicate that of an initial composite restoration.

Effect of different conditioning protocols on the adhesion of a glass ionomer cement to dentin

AIM

The purpose of this study was to assess the effect of different surface treatments on the shear bond strength (SBS) of a resin modified glass ionomer cement (RMGIC) to dentin.

METHODS AND MATERIALS

Forty human third molar teeth were randomly divided into four groups (n=10). The occlusal enamel was removed to obtain a flat surface of dentin. Each group was treated as follows: Group 1: 10% polyacrylic acid (positive control); Group 2: 37% phosphoric acid followed by 5% sodium hypochlorite (NaOCl); Group 3: 1.1% APF gel; and Group 4: no conditioning (negative control). Fuji II LC glass ionomer was bonded to dentin using a cylindrical mold. Samples were thermocycled and debonded using a shear force with a crosshead speed of 0.5 mm/min. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey tests (a = 0.05).

RESULTS

The mean SBS in Groups 1 through 4 were 11.562+/-3.148, 8.060+/-1.781, 8.830+/-1.554, and 3.074+/-0.784 (MPa), respectively. There were significant differences in the SBS between Group 1 with other groups (P<0.05). There were no statistically significant differences between Groups 2 and 3, but the SBS of both of them were significantly higher than that of Group 4 (P<0.05).

CONCLUSION

Although the dentin SBS of Fuji II LC after conditioning with APF and phosphoric acid followed by NaOCl was greater than the unconditioned group (Group 4), polyacrylic acid yielded the best result.

CLINICAL SIGNIFICANCE

Proper conditioning of dentin is effective in promoting close adaptation of RMGIC to dentin.

Effect of posts on the fracture resistance of load-cycled endodontically-treated premolars restored with direct composite resin

AIM

The aim of this study was to investigate the fracture resistance and failure mode of premolars restored with composite resin using various prefabricated posts.

METHODS AND MATERIALS

Sixty sound maxillary premolars were divided into four equal sized groups. All but the control group received endodontic treatment followed by placement of mesiodistocclusal (MOD) composite restorations (Tetric Ceram) as follows: Group T = no post, Group DT = fiber reinforced composite (FRC) post (DT Light), Group FL = prefabricated metal post (Filpost). The control group (C) had no cavities prepared. After thermal and load cycling, static load was applied at a 30 degrees angle until fracture. Failure modes were categorized as restorable and non-restorable. Data were analyzed using the analysis of variance (ANOVA) and Duncan tests (a = 0.05).

RESULTS

The mean values of fracture loads (N) for all groups were: C (880+/-258); T (691+/-239); DT (865+/-269); and FL (388+/-167). Statistically significant differences (P<0.05) were observed for all groups except between groups C and DT. The Chi Square test showed failure modes in groups C and DT were mostly restorable. The most non-restorable fractures were observed in group FT.

CONCLUSION

Intact teeth and the teeth restored with composite and quartz fiber posts had a similar fracture resistance and the failure modes were mostly restorable. The lowest fracture resistance and the most non-restorable failures were observed in conjunction with metal posts.

CLINICAL SIGNIFICANCE

The results of this in vitro study suggest the use of a quartz fiber post used in conjunction with an MOD composite resin restoration improves fracture resistance in an endodontically treated premolar.

Clinical evaluation of a resin-based desensitizing agent and a self-etching adhesive on the reduction of postoperative sensitivity of amalgam restorations

AIM

The aim of this randomized, double blind clinical trial was to compare three lining materials (Adper Prompt L-Pop, VivaSens, and Copalite) versus unlined restorations on postoperative cold sensitivity of class I amalgam restorations.

METHODS AND MATERIALS

Potential subjects were screened for the presence of four initial class I carious lesions on posterior teeth. Each tooth was assigned to treatments according to a randomized block design. After cavity preparation, teeth were lined with either VivaSens, Adper Prompt L-Pop, or Copalite, and one tooth remained unlined and served as a control. The cavities were filled with high copper amalgam (Oralloy). The time taken for a subject to respond to a standardized cold stimulus (CRM) was recorded at baseline, 24 hours, one week, and one month after treatment. Participants filled out a self-report questionnaire at each time point. Data was gathered by analysis of variance (ANOVA) and Duncan Multiple Comparisons tests (alpha=0.05).

RESULTS

Twenty subjects participated in this study. Comparisons within each group found no significant reduction in mean CRM for the Adper Prompt L-Pop group (P>0.05), but a significant difference in mean CRM for the VivaSens group was observed at one week and one month intervals after restoration (P<0.05). Copalite and the unlined groups showed significant mean CRM reductions after one day (P<0.05). No significant differences between groups receiving Adper Prompt L-Pop and Copalite were found at any time point (P>0.05). VivaSens showed more cold sensitivity than Adper Prompt L-Pop at one week and one month recalls (P<0.05), while the most cold sensitivity was found in the unlined group.

CONCLUSION

Adper Prompt L-Pop and Copalite reduced postoperative sensitivity to cold more than VivaSens and unlined groups at all assessment time points, 24 hours, one week, and one-month post treatment. The subjects receiving Copalite, VivaSens, and unlined restorations experienced greater sensitivity to cold at one month compared to baseline, while subjects receiving the Adper Prompt L-Pop liner experienced no greater sensitivity to cold from baseline to one month.

CLINICAL SIGNIFICANCE

Adper Prompt L-Pop as a liner under spherical high copper amalgam successfully reduced cold postoperative sensitivity.