Bağdagül Helvacıoğlu Kıvanç

Effects of Er:YAG laser and Nd:YAG laser treatment on the root canal dentin of human teeth: a SEM study

The objective of the study was to observe the morphological changes on root canal dentin after Er:YAG laser and Nd:YAG laser treatment. Twenty-one teeth biomechanically prepared were divided into three groups with seven teeth of each. Group A was unlased as a control. In group B, Er:YAG laser and in group C, Nd:YAG laser was applied to the root canal dentin. The roots were split longitudinally and examined using a scanning electron microscopy for the evaluation of debris, smear layer, and recrystallization. There was no statistically significant difference between the groups. This study indicates that laser beam is not effective in removing debris and smear layer.

Fracture resistance of thin‐walled roots restored with different post systems

AIM To compare the fracture resistance of thin-walled roots after restoration with different types of post systems. METHODOLOGY One hundred and sixty-five decoronated maxillary central incisors were root filled and randomly assigned to three groups with respect to the remaining dentine thickness of root (1.0 mm, 1.5 mm, 2.0 mm). Each group was randomly divided into five equal subgroups. The subgroups were restored with one of the following post systems: polyethylene woven fibre (R), composite resin cured by light-transmitting post + glass fibre post (L), electrical glass fibre post (E), composite corono-radicular restoration (C) and cast metal post (M). Standard cores were constructed using composite resin in the first four groups. The samples were subjected to a gradually increasing force (1 mm min(-1)). The force required to fracture was recorded. The data was analysed with anova and Tukey test (P = 0.05). RESULTS The cast metal post group had the highest fracture strength (P < 0.001). There was no significant difference in fracture resistance between the other four groups. Fracture resistance was affected largely by the remaining dentine thickness in fibre post groups; however, the difference was not significant. On the contrary in the cast metal post group load failure was inversely influenced by axio-proximal dimension of dentine walls. CONCLUSION The cast post group had a higher fracture strength than resin groups. The force required to fracture the roots was similar for all fibre post systems and for all dentine thicknesses.

Effect of light-activated bleaching on pulp chamber temperature rise: An in vitro study

This study aimed to compare the pulp chamber temperature changes that occur with the use of different light sources during vital bleaching with and without application of bleaching agents. One hundred and forty-four mandibular incisor teeth were divided into four groups (n = 36) according to the use of halogen light, light-emitting diode, 3 W and 1.5 W diode laser. The teeth in the main groups were divided into three subgroups (n = 12). First subgroup had no bleaching gel application. By White and Whiteness HP were applied with a thickness of 2 mm to the other subgroups respectively. The labial surfaces of the teeth were irradiated with a total time of 20 s. Temperature changes in the pulp chamber were measured and analysed by using anova and Tukey test. The 3 W diode laser induced the highest pulp chamber temperature rise (P = 0.000). Bleaching gel application reduced the temperature changes in the diode laser groups (P < 0.05). Diode laser activation during vital bleaching induces pulp chamber temperature rise, which may cause thermal tissue damage.

The effect of different adhesive system applications on push-out bond strengths of glass fiber posts

PURPOSE Over the past years, the adhesion of fiber posts luted with simplified adhesive systems has been a matter of great interest. The aim of this study was to assess the post retentive potential of a self-adhesive resin cement using different adhesive systems to compare the push-out bond strengths of fiber posts. MATERIALS AND METHODS The post spaces of 56 mandibular premolar roots were prepared and divided into 4 experimental groups and further divided into 2 subgroups according to testing time (n=7). The fiber posts (Rely X Fiber Post) were luted with a self-adhesive resin cement (RelyX Unicem) and one of the following adhesive systems: no adhesive, a total-etch adhesive resin (Single Bond), a two-step self-etch adhesive resin (Clearfil SE Bond) and a one-step self-etch adhesive resin (Clearfil S3 Bond). Each root was cut horizontally, and 1.5 mm thick six root segments were prepared. Push-out tests were performed after one week or three months (0.5 mm/min). Statistical analysis were performed with three-way ANOVA (α=.05). RESULTS Cervical root segments showed higher bond strength values than middle segments. Adhesive application increased the bond strength. For one week group, the total-etch adhesive resin Single Bond showed higher bond strength than the self-adhesive resin cement RelyX Unicem applied without adhesive resin at middle region. For 3 months group, the two-step self-etch adhesive resin Clearfil SE Bond showed the highest bond strength for both regions. Regarding the time considered, Clearfil SE Bond 3 months group showed higher bond strength values than one week group. CONCLUSION Using the adhesive resins in combination with the self-adhesive resin cement improves the bond strengths. The bond strength values of two-step self-etch adhesive resin Clearfil SE Bond improved as time passes.

Effect of post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts

The aim of this study was to evaluate the effect of different post-space treatments on the push-out bond strength and failure modes of glass fibre posts. Forty mandibular premolar roots were cut and endodontically treated. Post spaces were prepared and roots were divided into four groups. In group 1 distilled water irrigation (control), in group 2 2.25% NaOCl irrigation, in group 3 2.25% NaOCl + 17% EDTA irrigation were done and in group 4 diode laser was applied to the prepared post spaces. Scanning electron microscope (SEM) analysis was made for each group. Fibre posts were then luted with resin cement. Each root was prepared for push-out test. Data were statistically analysed with anova (P = 0.05). After push-out test, the failure modes were observed but not statistically analysed. There were statistically significant differences between Group 3 and Group 2 in both regions (P < 0.05), also in the middle region of Group 4 and Group 2 (P < 0.05). Cervical root segments showed higher bond strengths than middle ones in all groups (P < 0.05). The highest bond strength values were obtained from NaOCl/EDTA and the lowest bond strength values were obtained from NaOCl for both regions.

Microhardness of Packable Composites Used as Posts Condensed with Different Methods

The purpose of this in vitro study was to evaluate the microhardness of packable composite compacted with hand or ultrasonic pluggers in post spaces. A total of 168 extracted human anterior teeth were prepared with Gates Glidden and ParaPost drills after obturation. A primer and a dentin-bonding agent were applied to the etched surface. Half of the specimens were compacted with an ultrasonic tip and the other half with a mechanical hand compactor and all specimens were polymerized for each increment. The roots were then sectioned horizontally from 0, 2.5, 3, 3.5, 4, 4.5, and 5 mm starting from the coronal and sliced 2.5-mm long. The microhardness test was applied to each specimen. There were statistically significant differences between ultrasonically and hand-condensed groups in whole specimens (p < 0.001). There were no significant differences between groups of 0, 2.5, and 3 mm until 3.5 mm was reached. After 3.5-mm depth, there were significant differences between the groups (p < 0.001). Ultrasonic condensation of packable composites provided mechanical advantage over hand condensation in root canals measuring microhardness in different depths. However, when microhardness was measured at different depths, values decreased after the depth of 3.5 mm in both condensation groups.

The effect of the application of gaseous ozone and ND:YAG laser on glass‐fibre post bond strength

The aim of this study was to investigate the effects of the application of gaseous ozone and Nd:YAG laser on glass-fibre post bond strength. Forty-two madibular premolar roots were cut, endodontically instrumented and irrigated with 2.5% NaOCl. Post spaces were prepared and roots were divided into three groups (n = 14). The antimicrobial pretreatment was conducted as follows: gaseous ozone, Nd:YAG laser and control (no additional disinfection methods). Scanning electron microscope analysis was made for each group (n = 2). A resin cement was used for luting the posts. For push-out test, each root was cut horizontally (two cervical, two middle and two apical). Statistical analyses were performed with one-way anova (α = 0.05). Fracture types were observed. There was no statistically significant difference between the groups (P > 0.05). There were statistically significant differences in cervical and apical segments of laser and control groups (P < 0.05). The disinfection of the post spaces with Nd:YAG laser and ozone had no adverse effects on bond strength of glass-fibre post.

Fracture Resistance of Premolars Restored Either with Short Fiber or Polyethylene Woven Fiber‐Reinforced Composite

OBJECTIVE To compare the fracture resistance of endodontically treated maxillary premolars with one remaining cavity wall restored either with short fiber-reinforced composite or polyethylene woven fiber-reinforced composite. MATERIALS AND METHODS Forty-eight maxillary premolars were endodontically treated and randomly assigned to four groups (n = 12). Palatal cusp was removed, buccal wall was remained. In groups 1 to 3, standardized cavities were prepared in the palatal canal entrances. In group 1, short fiber-reinforced composite was used for restoration both of deep cavity and coronal part. In group 2, short fiber-reinforced composite was placed inside the deep cavity and core part of the restoration. Coronal restoration was restored by using conventional filler composite. In group 3, both deep cavities and coronal parts were built up by using conventional filler composite. In group 4, post space was prepared in the palatal canal. Polyethylene woven fiber-reinforced composite post then was placed into post space and the coronal part was restored by using conventional filler composite. Specimens were placed into a universal testing machine. The fracture loads were recorded and analyzed statistically using one-way ANOVA (α = 0.05). Fracture patterns were analyzed by using Chi-square test (α = 0.05). RESULTS No statistically significant difference was found in fracture strength (p > 0.05). Group 1 exhibited the highest and group 4 exhibited the lowest incidence of restorable fracture (p < 0.05). CONCLUSIONS The restoration of severely weakened premolar teeth with the use of short fiber-reinforced composite might have advantages over conventional filler composite or polyethylene woven fiber-reinforced composite techniques. CLINICAL SIGNIFICANCE The results of this in vitro study will be helpful to understand reinforced composite materials for restoring endodontically treated maxillary premolars. (J Esthet Restor Dent 28:412-418, 2016).

Apical transportation during removal of root canal filling with different retreatment systems

Introduction This study aimed to compare apical transportation during retreatment using ProTaper Universal retreatment (PTUR), Mtwo R and D-RaCe instruments in curved root canals. Methods 36 extracted mandibular molar teeth with curved mesiobuccal roots were selected. The teeth were embedded into acrylic blocks. The blocks were fixed on the experimental setup. After determining the working length (WL), mesiobuccal canals were prepared with ProTaper Universal rotary instruments to size F1 (20/0.06). After the obturation, the teeth were randomly divided into groups; the PTUR files were used as D1 (30/0.09) for coronal third and D2 (25/0.08) at WL Mtwo R files, R1 (15/0.05) and R2 (25/0.05) were used at WL D-RaCe files were used as DR1 (30/.10) in cervical third and DR2 (25/0.04) at WL Image J analysis software was used to measure the apical transportation. Differences between the 3 groups were analyzed with a 1-way ANOVA or Kruskal-Wallis tests. Results There was no significant difference between groups in the apical transportation in either the mesiodistal (p = 0.166) or buccolingual (p = 0.518) direction. Among the 3 groups, the apical transportation was the greatest in the D-RaCe group. Conclusions It can be concluded that all retreatment systems caused a similar level of apical transportation.

Kazein fosfopeptit-amorf kalsiyum fosfat (CPP-ACP) ve floridin ağartma ajanı uygulanmış mine mikrosertliği üzerine etkisi: ex vivo

Objective: The aim of this study was to compare the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and 1.23% acidulated phosphate fluoride (APF; pH 3.5) on the microhardness of enamel treated with a bleaching agent. Materials and Method: Enamel slices (n=32; 2×4 mm) were obtained from 8 mandibular permanent molar teeth. Specimens were embedded into acrylic resin blocks with the enamel surfaces facing upwards. Vickers microhardness (VHN) values of the specimens were recorded at baseline. The specimens were randomly divided into 4 experimental groups, and the experimental designation was as follows: Group 1: no treatment (control), Group 2: 35% hydrogen peroxide (HP), Group 3: HP + CPP-ACP, Group 4: HP + APF application. After treatments, VHN values were measured and recorded again. Specimens were stored in artificial saliva at 37 °C for 1 week. After 1 week second application was done and VHN of the specimens was registered once more. Data were statistically analyzed with ANOVA and Tukey post hoc tests. Values obtained at baseline, and first and second applications were compared using paired samples t-test (α=0.05). Results: In inter-group comparisons, no statistically significant difference in the enamel microhardness values was found between the baseline, and first and second applications (p>0.05). In intra-group comparisons, again, no statistically significant difference in the enamel microhardness values was found between the baseline, and first and second applications (p>0.05). Conclusion: According to the limitations of this study it can be concluded that neither the HP application nor the CPP-ACP or APF application after HP had any significant effect on the enamel microhardness.