Journal of Dental Medicine

Background and Aim: Increasing patient demands for esthetic, put the root coverage procedures in particular attention. Periodontal regeneration with GTR based root coverage methods is the most common treatment used. The purpose of this study was to compare guided tissue regeneration (GTR) with collagen membrane and a bone graft, with sub-epithelial connective tissue graft (SCTG), in treatment of gingival recession.

Materials and Methods: In this randomized clinical trial study, eleven healthy patients with no systemic diseases who had miller’s class I or II recession defects (gingival recession  2mm) were treated with SCTG or GTR using a collagen membrane and a bone graft. Clinical measurements were obtained at baseline and 6 months after surgery. These clinical measurements included recession depth (RD), recession width (RW), probing depth (PD), and clinical attachment level (CAL). Data were analyzed using independent t test with p<0.05 as the limit of significance.

Results: Both treatment methods resulted in a statistically significant reduction of recession depth (SCTG=2.3mm, GTR=2.1mm P<0.0001). CAL gain after 6 months was also improved in both groups (SCG= 2.5mm, GTR=2.1mm), compared to baseline (P<0.0001). No statistical differences were observed in RD, RW, CAL between test and control groups. Root coverage was similar in both methods (SCTG= 74.2%, GTR= 62.6%, P=0.87).

Conclusion: Based on the results of this study, the two techniques are clinically comparable. Therefore the use of collagen membrane and a bovine derived xenograft may alleviate the need for connective tissue graft.

Background and Aim: Achieving adhesion between restorative materials and dentin as a wet and dynamic surface is an important topic in restorative and especially in conservative dentistry. Adhesion of new dentin bonding systems depends on the formation of hybrid layer and micromechanical retention. Nevertheless, an ideal adhesive system has not yet been introduced .Recent studies reveal an increase in bonding stability when the collagen is removed from demineralized dentin surfaces. This study investigates the effect of collagen removal on the shear bond strength of four single bottle dentin bonding systems regarding their structural differences.

Materials and Methods: This experimental study was performed on 56 intact human premolar teeth. Smooth surfaces of dentin were prepared on buccal & lingual aspects of teeth, providing 112 dentin surfaces. The dentin surfaces were etched with 37% phosphoric acid for 15 seconds and then rinsed. The specimens were divided into 8 groups. Single bottle adhesive systems [Single Bond (3M), One-Step (Bisco), Prime & Bond NT (Dentsply), and Excite (Vivadent)] were then applied on the dentin surfaces of 4 groups using the wet bonding technique. In the other 4 groups, the demineralized dentin surfaces were treated with a 5.25% solution of sodium hypochlorite for one minute in order to remove the surface organic components. The adhesive systems mentioned before were applied to these 4 groups with the same wet bonding technique. A cylinder of Z100 (3M) dental composite with a 3 mm diameter and 2 mm height was placed on the adhesive covered dentin surface of all groups and light-cured (400 mW/cm2 ,40 sec on each side). The specimens were kept in distilled water at room temperature for one week and then thermocycled for 3000 times (5-55 oc). Shear bond strength of specimens was measured using an Instron (1495) universal mechanical testing machine with cross-head speed of 0.5 mm/minute and chisel form shearing blade. Data were analyzed by Two Way ANOVA and Tukey HSD tests with p<0.05 as the limit of significance.

Results: The mean & standard deviation of shear bond strengths (in Mpa unit) of all groups were as follows: One-Step = 19.60 1.83 One-step +H = 19.72 2.01 Single Bond =21.44 3.94 Single Bond +H =18.26 2.85 Prime&Bond NT=26.51 5.02 Prime&Bond NT+H =26.98 5.70 Excite =29.78 3.85 Excite +H =19.07 9.94 Analysis of the results revealed that the use of 5.25% sodium hypochlorite for one minute on the surface of demineralized dentin significantly decreased the shear bond strength of Excite and Single Bond (P<0.05). For Prime & Bond NT and One-Step, shear bond strength increased with this treatment but was not statistically significant (P>0.05).

Conclusion: Based on the results of this study, collagen removal from demineralized dentin surface caused a significant decrease in shear bond strength of alcohol & water/alcohol based bonding systems, while the bonding strength of the acetone based systems was not affected. Therefore, the effect of collagen removal on shear bond strength depends on the bonding system applied and its solvent type.

Background and Aim: Furcation defects are one of the most challenging problems in periodontal therapy. Regenerative treatment significantly improves the prognosis of the involved teeth. The aim of this study was to compare Bio-Oss plus 10% collagen in combination with either a bioabsorbable collagen barrier (BO/GTR), or coronally advanced flap (BO/CF), in treating human mandibular class II furcation defects.

Materials and Methods: This clinical trial included 10 patients with 10 pairs of similar periodontal defects. Each defect was randomly assigned to treatment with BO/CF or BO/GTR. Following basic therapy, baseline measurements were recorded including probing pocket depth (PPD),closed horizontal probing depth (CHPD), clinical attachment level (CAL), and gingival margin position (CEJ-GM), together with plaque and gingival indices. Hard tissue measurements were performed during surgery to determine alveolar crestal height (CEJ-AC), and vertical and horizontal open probing depth (OVPD, OHPD).After 6 months, all sites were re-entered and soft and hard tissue measurements were recorded.

Results: Both surgical procedures significantly reduced probing depth and improved clinical attachment levels, with no significant difference between groups. Gingival margin position (CEJ-GM), was improved in the BO/CF group (0.66±0.51 mm, p<0.05), but not statistically different from BO/GTR group in which remained relatively constant (0.00±0.81 mm). Vertical defect resolution was significant in each groups (BO/CF:3.17±1.47 mm, BO/GTR:3.33±0.51mm). Horizontal defect resolution was also significant with either procedure (BO/CF:3.67±1.31 mm, BO/GTR:3.80±1.83 mm), with no statistically significant difference between groups. Data were analyzed with wilcoxon and Mann-Whitney tests with p<0.05 as the level of significance.

Conclusion: Based on the results of this study, treatment of mandibular class II furcation defects with both procedures resulted in statistically significant improvement in open and closed probing measurements, with no significant difference between treatment groups. In BO/CF group there was an additional improvement in gingival recession (CEJ-GM) measurement, which could be attributed to applying crown-attached sutures by the use of orthodontic brackets.

Background and Aim: Several materials have been introduced for retrograde fillings, pulp capping and sealing root perforations, but their biological effect on vital tissues and cells is not clear. The purpose of this study was to evaluate the reaction of human periodontal ligament fibroblasts to four root canal filling materials: Pro Root MTA, Root MTA, Portland cement and amalgam.

Materials and Methods: In this experimental study, impacted or semi impacted third molar teeth were extracted in aseptic conditions and tissues around the roots were used to obtain fibroblast cell line. After proliferation, cells were cultured in chamber slides and extracts of materials were added to wells. Fibronectin, type I collagen and TGF-  expression were measured by immunocytochemistry method. Data were analyzed by SPSS 11.0 using one way ANOVA and Tukey test. P<0.05 was considered as the limit of significance.

Results: Collagen I expression was higher in Pro Root MTA group after 24 hours (p<0.05) and in Portland cement group and positive controls after 48  hours. Portland cement group showed the highest expression of collagen after 1 week. There was no significant difference in fibronectin expression after 24 hours. After 1 week the highest expression of fibronectin was seen in Portland cement, Root MTA and Pro Root MTA groups. TGF-  expression was higher in amalgam, Root MTA and Pro Root MTA specimens after 24 hours and was the highest in Pro Root MTA group after 48 hours.

Conclusion: Based on the results of this study, Portland cement and Root MTA are comparable with Pro Root MTA and better than amalgam regarding their effects on human periodontal ligament fibroblasts.

Background and Aim: Sodium hypochlorite can remove the organic phase of the demineralized dentin and it produces direct resin bonding with hydroxyapatite crystals. Therefore, the hydrolytic degradation of collagen fibrils which might affect the bonding durability is removed. The aim of this study was to evaluate the effect of collagen fibrils removal by 10% NaOCl on dentin shear bond strength of two total etch and self etch adhesive systems.
Materials and Methods: Sixty extracted human premolar teeth were used in this study. Buccal surface of teeth were grounded until dentin was exposed. Then teeth were divided into four groups. According to dentin surface treatment, experimental groups were as follows: Group I: Single Bond (3M) according to manufacture instruction, Group II: 10% NaOCl+Single bond (3M), Group III: Clearfil SE Bond (Kuraray) according to manufacture instruction, and Group IV: Clearfil SE Bond primer. After that, the specimens were immersed in 50% acetone solution for removing extra monomer. Then the specimens were rinsed and dried. 10% NaOCl was applied and finally adhesive was used. Then composite was bonded to the treated surfaces using a 4 2 mm cylindrical plastic mold. Specimens were thermocycled for 500 cycles (5-55ºC). A shear load was employed by a universal testing machine with a cross head speed of 1mm/min. The data were analyzed for statistical significance with One-way ANOVA, Two-way ANOVA and Tukey HSD post-hoc tests.
Results: The mean shear bond strengths of groups were as follows: Single Bond=16.8±4.2, Clearfil SE Bond=23.7±4.07, Single Bond+NaOCl=10.5±4.34, Clearfil SE Bond+NaOCl=23.3±3.65 MPa. Statistical analysis revealed that using 10% NaOCl significantly decreased the shear bond strength in Single Bond group (P=0.00), but caused no significant difference in the shear bond strength in Clearfil SE Bond group (P=0.99).
Conclusion: Based on the results of this study, NaOCl treatment did not improve the bond strength in self etch adhesive and caused a significant decrease in the bond strength of total etch adhesive system.