Objectives: This study aimed to assess the effect of applying casein phosphopeptide–amorphous calcium phosphate (CPP-ACP) paste, casein phosphopeptide–amorphous calcium phosphate fluoride (CPP-ACPF) paste and sodium fluoride gel on surface microhardness of enamel after microabrasion.

Materials and Methods: Thirty freshly extracted human premolars were selected. All samples were subjected to hardness indentations made with the Vickers hardness machine and the average value was recorded as the initial surface microhardness. The specimens were then randomly divided into three groups (n=10) of CPP-ACPF, fluoride and CPP-ACP. The teeth were micro-abraded with Opalustre. Microhardness test was performed to assess the post-abrasion hardness. Three remineralization modalities were performed on samples of each group. The enamel surface microhardness measurements were performed. To compare the difference between groups, the rehardening and softening values were defined. One-way ANOVA and Tukey’s post hoc test at a significance level of 5% were used for statistical analysis.

Results: The mean microhardness value (MMV) had a significant decrease after microabrasion from baseline. The MMV had a significant increase after remineralization in all groups. The MMV of CPP-ACPF group was significantly more than that of fluoride group (P=0.027). The rehardening value of fluoride group was significantly more than that of other groups (P<0.001).

Conclusion: All the remineralizing agents were effective for rehardening the enamel after microabrasion. The CPP-ACP and CPP-ACPF pastes are effective, but to a lesser extent than neutral sodium fluoride gel in remineralizing enamel surface. Incorporation of fluoride to CPP-ACP formulation does not provide any additional remineralizing potential.

Keywords: Casein phosphopeptide-amorphous calcium phosphate nanocomplex; Enamel Microabrasion; Hardness; Sodium Fluoride

Objectives: The aim of the study was to compare the effect of fifth and seventh generation bonding agent on sealant success.

Materials and Methods: Sixty-four school children aged six to nine years received sealants in four permanent molars in a split mouth design, such that each patient received sealant in the first permanent molar with fifth generation bonding agent in one arch and seventh generation bonding agent in the other arch; contra-lateral molars were sealed with sealant alone. The evaluation was carried out at baseline, three months, six months and 12 months, according to the criteria by Feigal et al, in 2000. Chi- square test was used to analyze data at P<0.05 level of significance.

Results: Statistically significant differences were found for sealant retention between fifth generation and sealant group, and fifth generation and seventh generation groups; whereas, no significant difference was found for sealant retention between seventh generation and sealant group at three, six and 12 months.

Conclusion: As separate etch and rinse steps are not required for seventh generation bonding agents, and almost similar results were obtained for both sealant and seventh generation groups, it can be concluded that application of sealant along with a seventh generation bonding agent may enhance sealant success and can be used for caries prevention in preventive programs.

Key words:  Pit and Fissure Sealants; Dental Caries; Adhesives

Objectives: The aim of this study was to evaluate the effect of gutta percha/AH26 and Resilon/RealSeal SE on residual antimicrobial activity of chlorhexidine (CHX) in human root dentin and suggest the best filling material when CHX is used as final irrigant.

Materials and Methods: One-hundred and forty-four single-rooted human teeth were selected for this study. Canals were instrumented to the apical size #35. Smear layer was removed using 5.25% NaOCl and 17% EDTA and then 108 teeth were irrigated with 2% CHX and randomly divided into three groups of gutta percha/AH26, Resilon/RealSeal SE and positive controls. Each group was divided into three subgroups for different time intervals (one, three and six weeks). Thirty-six teeth, as negative controls, were irrigated with saline and obturated with gutta percha/AH26 and Resilon/RealSeal SE. Dentin powder was prepared at the afore-mentioned intervals. After exposure to Enterococcus faecalis for 24 hours, colony forming units (CFUs) were counted and residual antimicrobial activity was calculated. The data were analyzed using the Kruskal Wallis test and one-way ANOVA. The significance level was set at P<0.05.

Results: The antimicrobial activity of CHX gradually decreased in a time-dependent manner but it maintained over 95% of its antimicrobial activity after six weeks. Moreover, Resilon/RealSeal SE significantly decreased the antimicrobial activity of CHX in comparison with gutta-percha/AH26 (P<0.05).

Conclusion: After a final irrigation with CHX, gutta-percha/AH26 is a better choice for root canal obturation.

Key words: Chlorhexidine; Gutta-Percha; Epoxy resin AH-26; Resilon sealer. 

Objectives: Probiotic approaches are being considered to eliminate pathogenic microorganisms and are an alternative and promising way to combat infections by using harmless bacteria to displace pathogenic microorganisms. The aim of this study was to evaluate the effectiveness of commercially available freeze dried powdered probiotics on mutans streptococci count among 12-15 year-old Indian schoolchildren.

Materials and Methods: The study was conducted in two phases of in-vitro (phase I) and in-vivo (phase II) study, which was a double blind, randomized and placebo controlled clinical trial. A total of 33 schoolchildren between 12-15 years were included in the study. They were randomly allocated to three groups. Group A included 11 children using freeze dried Lactobacillus acidophilus, Bifidobacterium longum, Bifidobacterium bifidum and Bifidobacterium lactis. Group B included 11 children using freeze dried lactic acid bacillus only. Group C included 11 children using placebo powder. The study was conducted over a period of three weeks and examination and sampling of the subjects were done on days 0 (baseline), seven, 14 and 21.

Results: For both the intervention groups A and B, statistically significant reduction (P<0.05) in salivary mutans streptococci counts was recorded up to the second week.

Conclusion: Oral administration of probiotics showed a short-term effect on reduction of mutans streptococci count and showed a preventive role in caries development.

Key words: Probiotics; Viridans Streptococci; Dental Caries.

Objectives: This study sought to assess the effects of length and inclination of implants on stress distribution in an implant and terminal abutment teeth in an implant assisted-removable partial denture (RPD) using three-dimensional (3D) finite element analysis (FEA).  

Materials and Methods: In this in vitro study, a 3D finite element model of a partially dentate mandible with a distal extension RPD (DERPD) and dental implants was designed to analyze stress distribution in bone around terminal abutment teeth (first premolar) and implants with different lengths (7 and 10 mm) and angles (0°, 10° and 15°).

Results: Stress in the periodontal ligament (PDL) of the first premolar teeth ranged between 0.133 MPa in 10mm implants with 15° angle and 0.248 MPa in 7mm implants with 0° angle. The minimum stress was noted in implants with 10mm length with 0° angle (19.33 MPa) while maximum stress (25.78 MPa) was found in implants with 10mm length and 15° angle. In implants with 7 mm length, with an increase in implant angle, the stress on implants gradually increased. In implants with 10 mm length, increasing the implant angle gradually increased the stress on implants.

Conclusion: Not only the length of implant but also the angle of implantation are important to minimize stress on implants. The results showed that vertical implant placement results in lower stress on implants and by increasing the angle, distribution of stress gradually increases.

Keywords: Dental Implants, Single-Tooth; Dental Stress Analysis; Finite Element Analysis.

Objectives: This study aimed to evaluate the effects of saliva contamination on the metallic bracket microleakage bonded with two moisture-tolerant bonding systems.

Materials and Methods:  Ninety freshly extracted premolar teeth were randomly divided into six groups of 15 with the following treatments: G1 (control): After acid etching, Assure primer and Assure adhesive were applied to non-contaminated enamel surfaces. G2 (contaminated after etching): The etched enamel surface was exposed to saliva, then Assure primer and Assure adhesive were applied. G3 (contaminated after priming): Saliva contamination was done after application of Assure primer. The exact same procedures were applied to groups G4 to G6 except that TIMP primer and Transbond Plus adhesive system were used.  

To measure the microleakage score, the teeth were stained with 2% methylene blue for 24 hours, sectioned and examined under a stereomicroscope at ×16 magnification. Data analysis was performed using Fisher’s exact test.

Results: In dry conditions, Assure and TMIP were not significantly different in terms of microleakage scores.  All contaminated groups exhibited higher microleakage score at the enamel/adhesive interface compared to the bracket/adhesive interface (P< 0.01). In wet conditions, Assure groups showed higher microleakage at the enamel-adhesive interface compared to the TMIP groups (P<0.05). At the bracket-adhesive interface, the microleakage scores were not significantly different in saliva contaminated groups compared to the controls.

Conclusion: Saliva contamination caused greater microleakage at the enamel-adhesive interface compared to the adhesive-bracket interface.

Keywords: Orthodontic Brackets; Adhesives; Saliva

Objectives: Accurate localization of the inferior alveolar canal (IAC) is extremely important in some dental treatments. Anatomical variation of the canal means that it can be difficult to locate. The purpose of this study was to assess the relationship of the gonial angle (GA) size and IAC position using cone beam computed tomography (CBCT).

Materials and Methods: In this in vitro study, 61 dry adult human hemi-mandibles were used. The CBCT scans were taken of all samples and GA was measured on all CBCT scans. The samples were divided into two groups of low angle (≤125°) and high angle (>125°). The canal dimensions, length and course were evaluated. On the sagittal view, the IAC path was classified as type A, B or C. On the axial view, canal course was defined as A1 or A2 according to the mental foramen angle.

Results: The average GA size was 121.8±7.05° at the right side and 123.8±6.32° at the left side. On the sagittal view, there was a significant correlation between the GA size and the canal course (P=0.04). In the high-angle group, type A was dominant; whereas in the low-angle group, type B was more common. On the axial view of IAC course, type A1 was more common (73.43%).

Conclusion: The results showed that GA size was associated with IAC course. In cases with a larger GA, the canal runs in a more straightforward path, and at the same level as the mental foramen.

Keywords: Cone Beam Computed Tomography; Mandibular Nerve; Mandible

Objectives:  The efficacy of adding platelet-rich plasma (PRP) to demineralized freeze-dried bone allograft (DFDBA) in order to improve the clinical and radiographic results obtained in treatment of deep periodontal intrabony defects has yet to be fully elucidated.

Materials ­and Methods: This double blind, split-mouth randomized controlled clinical trial was conducted on 12 patients with two comparable bilateral intrabony defects. Each pair of defects was randomly treated with DFDBA+PRP (test) or DFDBA alone (control).  Clinical attachment level (CAL), intrabony defect depth (IDD), distance from the stent to the alveolar crest and pocket depth (PD) as well as radiographic parameters including the radiographic defect depth, width and angulation were measured at baseline and six months post-operatively. The paired t-test was used to compare the pre and post-treatment values and the unpaired t-test compared the test and control groups.

Results: The mean reductions in PD and CAL were 4.5 ±1.3 mm and 3.6±1.6 mm in sites treated with DFDBA+ PRP, respectively (P<0.01); these reductions were 4.1±1.4 mm and 3.5±1.3 mm, respectively in DFDBA group (P<0.01). Radiographic evaluation revealed 2.5±1.1 mm reduction in the radiographic defect depth in the test and 2.1±1.2 mm in the control sites. The defect angulation increased at both sites. Statistically, there were no significant differences between the two treatment modalities (P<0.01).

Conclusion: This study showed that both treatments resulted in significant PD reduction, CAL gain and IDD reduction. Also, PRP failed to enhance the results obtained by DFDBA.

Key words: Cell- and Tissue-Based Therapy; Allografts; Cone-Beam Computed Tomography; Platelet-Rich Plasma

Objectives: The purpose of this study was to compare the accuracy of implant position transfer and surface detail reproduction using two impression techniques and materials.

Materials and Methods: A metal model with two implants and three grooves of 0.25, 0.50 and 0.75 mm in depth on the flat superior surface of a die was fabricated. Ten regular-body polyether (PE) and 10 regular-body polyvinyl siloxane (PVS) impressions with square and conical transfer copings using open tray and closed tray techniques were made for each group. Impressions were poured with type IV stone, and linear and angular displacements of the replica heads were evaluated using a coordinate measuring machine (CMM). Also, accurate reproduction of the grooves was evaluated by a video measuring machine (VMM). These measurements were compared with the measurements calculated on the reference model that served as control, and the data were analyzed with two-way ANOVA and t-test at P= 0.05.

Results: There was less linear displacement for PVS and less angular displacement for PE in closed-tray technique, and less linear displacement for PE in open tray technique (P<0.001). Also, the open tray technique showed less angular displacement with the use of PVS impression material. Detail reproduction accuracy was the same in all the groups (P>0.05(.

Conclusion: The open tray technique was more accurate using PE, and also both closed tray and open tray techniques had acceptable results with the use of PVS. The choice of impression material and technique made no significant difference in surface detail reproduction.

Knowledge about the morphology of the root canal system is a pre-requisite for achieving a successful outcome in root canal treatment. In this report, a patient with a maxillary lateral incisor which had previously undergone orthograde endodontic retreatment for two times is discussed. The tooth had been misdiagnosed with a palatal groove or a root fracture, its prognosis had been determined to be poor and extraction was advised by a practitioner. During our evaluation, an unrecognized supernumerary root and root canal were detected and the tooth was maintained successfully with orthograde endodontic retreatment. The use of cone beam computed tomography (CBCT) and magnification were of significance in the treatment process of this case.

Key words: Tooth, Supernumerary; Incisor; Maxilla; Root Canal Therapy