Melek Akman

Influence of several fibre-reinforced composite restoration techniques on cusp movement and fracture strength of molar teeth

AIM To compare mean cusp movement in molar teeth with endodontic access and mesial-occlusal-distal (MOD) cavities before and after restoration with several fibre-reinforced composite restoration techniques under loading and to evaluate the effect of restoration technique on fracture strength. METHODOLOGY Reference points were marked at the mesial cusp ridges of extracted human mandibular molar teeth. Digital images were taken under loading (300 N) using a stereomicroscope (Leica MZ16A; Wetzlar, Germany). Three-dimensional (3D) distances between the reference points were recorded (Leica, Stereo-Explorer, 2.1) as controls. Standard MOD cavities were prepared and restored as follows (n = 10), group 1: composite restoration (Clearfil AP-X; Kuraray, Tokyo, Japan); group 2: cavity lined with polyethylene fibre (Ribbond, Ribbond Inc., Seattle, WA, USA) in combination with flowable resin (Protect-Liner F; Kuraray, Tokyo, Japan) before composite restoration; group 3: polyethylene fibre inserted on occlusal surface of the tooth from buccal to lingual after finishing the composite restoration; group 4: missing walls were restored with composite resin and inner surfaces of the axial walls were then reinforced with polyethylene fibre placed circumferentially before the composite restoration. The restored teeth were re-loaded, digital images were re-taken and the 3D distance between the reference points was recorded in μm. Comparisons of the restoration techniques, the effectiveness of restoration for each group were analysed statistically (Kruskall-Wallis, paired-samples t-test). The teeth were then loaded until failure (5 mm min(-1) ), the data were recorded (N) and analysed statistically (Kruskall-Wallis test). RESULTS A significant difference occurred amongst the groups in terms of cusp movement (P = 0.018). All the groups revealed a decrease in inter-cuspal width when compared to their initial records. The mean values of these decreases were as follows: group 1 17.6 (P = 0.003), group 2 6.7 (not sig), group 3 6.6 (not sig) and group 4 0.85 (not sig) μm. No significant difference was found amongst the fracture strength values (P = 0.22). In group 1, 90% of the fractures were non-restorable, whereas in group 3 100% of the fractures were restorable. CONCLUSIONS Regardless of restoration technique, fibre reinforcement of composite restorations decreased cusp movement in molar teeth with MOD and endodontic access cavities but did not affect fracture strength.

Fracture resistance of roots obturated with a novel calcium silicate-based endodontic sealer (BioRoot RCS)

Abstract The aim of this ex vivo study was to evaluate the vertical-fracture resistance of roots obturated with a newly developed tricalcium silicate cement (BioRoot RCS; Septodont, Saint Maur Des Fosses, France) using cold lateral compaction technique (LC) or matched-taper single-cone gutta-percha technique (SC). Decoronated 82 single-rooted mandibular premolars were chemo-mechanically prepared and then randomly divided into 6 experimental groups (n = 12) and 2 control groups (n = 5): Group 1 iRoot SP-LC; Group 2 iRoot SP-SC; Group 3 MTA Fillapex-LC; Group 4 MTA Fillapex-SC; Group 5 BioRoot RCS-LC and Group 6 BioRoot RCS-SC. In the positive-control group, roots were instrumented but not filled, and in the negative-control group, roots were neither instrumented nor filled. All samples were incubated for two weeks and then subjected to vertical loading force (1 mm/min) until fracture. The force required to fracture each specimen were determined, and the data were statistically analyzed. The highest significant fracture resistance was recorded for the iRoot SP-LC, iRoot SP-SC, BioRoot RCS-LC, and BioRoot RCS-SC groups, with no significant difference among them (p > 0.05) when compared with the positive-control group (p < 0.05), whereas the lowest significant values were observed in the MTA Fillapex-LC and MTA Fillapex-SC groups (p < 0.05). The vertical fracture resistance of roots obturated with BioRoot RCS and iRoot SP sealers using either LC or SC technique was found to be similar to that of intact teeth. BioRoot RCS, newly developed tricalcium silicate cement, might have the potential to reinforce the instrumented teeth against vertical root fracture.

Efficacy of Twisted File Adaptive, Reciproc and ProTaper Universal Retreatment instruments for root-canal-filling removal: A cone-beam computed tomography study

The aim of this study was to evaluate the efficacy of Twisted File (TF) Adaptive, Reciproc, and ProTaper Universal Retreatment (UR) System instruments for removing root-canal-filling. Sixty single rooted teeth were decoronated, instrumented and obturated. Preoperative CBCT scans were taken and the teeth were retreated with TF Adaptive, Reciproc, ProTaper UR, or hand files (n=15). Then, the teeth were rescanned, and the percentage volume of the residual root-canal-filling material was established. The total time for retreatment was recorded, and the data was statistically analyzed. The statistical ranking of the residual filling material volume was as follows: hand file=TF Adaptive>ProTaper UR=Reciproc. The ProTaper UR and Reciproc systems required shorter periods of time for retreatment. Root canal filling was more efficiently removed by using Reciproc and ProTaper UR instruments than TF Adaptive instruments and hand files. The TF Adaptive system was advantageous over hand files with regard to operating time.

Tooth discoloration effects of calcium silicate based barrier materials used in revascularization and treatment with internal bleaching

Background/purpose Usage of barrier materials is an important step in revascularization procedure. One of the undesired properties of these barrier materials is to cause coronal tooth discoloration. The aim of this in vitro study was to evaluate the tooth discoloration induced by ProRoot MTA (PMTA), Biodentine, and MM-MTA, as well as the efficacy of internal bleaching on this discoloration. Materials and methods Forty-two maxillary incisor teeth were prepared. Triple antibiotic paste (TAP) was placed in the root canals and incubated for 3 weeks. After removing the TAP, blood embedded spongostans were inserted into the root canals, and PMTA, Biodentine, or MM-MTA was placed over them. The teeth were incubated for 4 weeks at 37 °C; then, the internal bleaching agent was sealed for one week. The tooth color was measured throughout the study and the color change values (ΔE) of each specimen were calculated, and the data was statistically analyzed using the one-way ANOVA and Tamhanes T2 tests. Results The TAP significantly decreased the luminosity of the teeth (p < 0.05); however, no significant differences were observed between the tooth discolorations induced by the PMTA, Biodentine, and MM-MTA (p > 0.05). The teeth in the Biodentine group were more whitened than those of the PMTA and MM-MTA groups (p < 0.05). Conclusion Although the PMTA, Biodentine, and MM-MTA caused similar color alterations in the teeth, more bleaching was observed on those teeth discolored using TAP + blood + Biodentine.

Effect of intracanal medicaments on the push-out bond strength of Biodentine in comparison with Bioaggregate apical plugs

Abstract To evaluate the effect of intracanal medicaments on the push-out bond strength of Biodentine in comparison with DiaRoot BioAggregate (BA) when used as apical plugs. Forty single-rooted teeth were prepared using Peeso reamers. The samples were divided into four groups. The intracanal medicaments were applied to the root canals as follows: Group1: a combination of metronidazole–ciprofloxacin–cefaclor, Group2: a combination of metronidazole–ciprofloxacin, Group3: calcium hydroxide, and Group4: no medication. After 21 days, the medicaments were removed. The apical part of each root was horizontally sectioned into 1-mm thick slices. The samples were divided into two subgroups, and the following materials were placed: Biodentine, DiaRoot-BioAggregate. After 48-h incubation, the push-out bond strength was measured. The data were analyzed by a two-way ANOVA. Biodentine showed a significantly higher mean push-out bond strength value than DiaRoot-BioAggregate (P = 0.00). The medications have an effect on the push-out bond strength of both materials (P = 0.002). Biodentine showed better adhesive performance as an apical plug than DiaRoot-BioAggregate.

Paramolar Diş ile Füzyona Uğramış Sıra Dışı Bir Maksiller Molar Dişin Endodontik Tedavisi

242 üzyon, iki veya daha fazla dişin gelişimleri sırasında mine veya dentini içerecek şekilde kaynaşmasıdır ve diş gelişimi sırasında oluştuğu aşamanın zamanına bağlı olarak “parsiyel” veya “tam füzyon” olarak adlandırılmaktadır.1 Füzyonun görülme sıklığı süt dişlerinde %0,5 iken daimi dişlerde %0,1’dir. Cinsiyetler arasında görülme olasılığı açısından fark yoktur.2,3 Füzyon iki bitişik diş arasında görülmektedir ve süpernumere bir diş ile daimi bir diş arasında görülme olasılığı çok azdır.4

The effect of Nd:YAG laser irradiation on root surface: shear-bond strength and SEM–EDX study

To investigate the effects of Nd:YAG laser and 17% EDTA treatment on root-dentin mineral content using scanning electron microscope–energy dispersive X-ray spectroscopy (SEM–EDX) and on shear-bond strength of epoxy-resin-based sealer (AH Plus) to root dentin. Twelve extracted premolars were decoronated and roots were sectioned, so that 24 two-root halves were obtained. Element levels of each half were examined by SEM/EDX, and AH Plus build-ups were created. After shear-testing, the test surfaces were reground and subjected to a 5.25% NaOCl. Two subgroups were created according to the surface treatment (n = 12): G1, with 17% EDTA for 5 min; G2, with the Nd:YAG laser. The element level analysis and shear-bond strength test were repeated for each half; the data were recorded (MPa) and analyzed (paired samples t-test). The EDTA treatment increased the O, C, Ca/P ratio (p < 0.001), decreased Ca, P content (p = 0.000), but did not change Na, Mg content (p > 0.05). The Nd:YAG laser increased O, Ca/P ratio (p < 0.001), and decreased the Ca, P content (p = 0.000). The C, Mg, Na content did not change with the Nd:YAG laser (p > 0.05). Both 17% EDTA and Nd:YAG laser had an effect on the mineral content of roots. The 17% EDTA treatment decreased the shear-bond strength of AH Plus to root dentin (p = 0.000); however, the Nd:YAG laser did not affect the bond strength (p = 0.238). Thus, an Nd:YAG laser can be used for disinfection of the root canal when AH Plus is used as a sealer.

Which is effective on bond strength of resin-based sealers: incorporation of powdered dentin to primer or adhesive?

The aim of this study was to investigate the effect of adding powdered dentin to primer or adhesive in a self-etch system on the shear bond strength of three resin-based sealers. Seventy-two premolars were sectioned buccolingually, and 144 root halves were divided into three groups according to the sealer used: epoxy resin-based sealer (AH Plus), methacrylate resin-based (RealSeal, Hybrid Root SEAL) n = 48. The surfaces were irrigated with 5% NaOCl, 17% EDTA, distilled water for 5 min. Four subgroups were created (n = 12): control group; Clearfil Liner Bond 2 V treated group; powdered dentin added to the primer of Clearfil Liner Bond 2 V (40 wt.%); and powdered dentin added to the adhesive of Clearfil Liner Bond 2 V (20 wt.%). Dentin powder was prepared. Three mm high buildups with a constant surface area of 3.45 mm2 were created using the sealers and allowed to set (37 ºC, 100% humid, 72 h). The samples were tested to failure for shear bond strength (1 mm/min). The data were calculated (MPa) and analyzed using two-way ANOVA, one-way ANOVA, and Tukey HSD tests. Adhesive use decreased the bonding performance of AH Plus (p = 0.00). Mean bond strength of the other sealers was found similar to control. Primer or adhesive resin with powdered dentin did not increase the adhesive performance of the self-etch system used. The shear bond strength of RealSeal was significantly increased when powdered dentin was added to primer or adhesive (p = 0.00). The effect of adding powdered-dentine to primer or adhesive in a self-etch system on the shear bond strength was sealer-dependent .

Perforasyon tamir materyallerinin sızıntı ve kalitesi: İntrakoronal ve retrograd tekniklerin karşılaştırılması

Amac: Bu in vitro calismanin amaci, perforasyon tamir materyallerinin, perforasyon bolgesine ortograd ya da retrograd yerlestirildiginde, sizinti ve kalitesini degerlendirmektir. Gerec ve Yontemler: Cekilmis insan molar dislerin mesial ve distal kok yuzeylerinde, disin uzun aksina 45 derecelik aciyla elmas bir frez ile kasten perforasyonlar olusturuldu. Mesial perforasyonlar intrakoronal olarak su materyaller kullanilarak tamir edildi: IRM (Dentsply), amalgam (Dentsply), Dyract (Dentsply), SuperBond C&B (Sun Medical) and MTA (Dentsply). Siman ile giris kavitesi doldurulduktan sonra distal perforasyonlar ayni materyaller ile retrograd olarak tamir edildi. Disler %100 nemli ortamda 24 saat saklandi. Perforasyon bolgeleri 24 saat %2’lik metilen mavisinde bekletildi. Disler kesilerek, 20x ve 40x buyutme ile stereomikroskop altinda incelendi ve boya penetrasyonuna gore tasmis, yeterli ve yetersiz olarak skorlandi. Bulgular: Veriler Kruskal-Wallis ve MannWhitney U-testleri ile analiz edildi. Restorasyon teknikleri arasinda onemli derecede fark bulundu (p < 0.05). Tum materyallerde retrograd teknik kullanildigi zaman daha az sizinti gozlendi (p < 0.05). Giris kavitesi boyunca perforasyonun tamiri, %86 tasmis ya da yetersiz bulundu. Retrograd olarak uygulandigi zaman IRM %80, MTA %60 oraninda sizinti olmadan yeterli bulundu. Sonuc: Retrograd teknik kullanarak perforasyonlarin tamiri, kullanilan materyalin etkisi olmaksizin yeterli restorasyonun sayisi onemli derecede artti. IRM retrograd uygulandigi zaman MTA’yi takiben en iyi kapamayi sagladi.