Influence of age and experience with magnification on locating the second mesiobuccal canal in maxillary first molars: A preliminary study.

The aim was to evaluate the effectiveness of clinical methods in identifying the presence of second mesiobuccal canal in maxillary first molars. The influence of age and experience with microscopy was also assessed. Sixty six teeth were selected and the mesiobuccal canal was confirmed in all of the samples by Cone-Beam Computed Tomography. After endodontic cavity access, teeth were evaluated through direct visual; dental loupe and operating microscope. None of the methods was successful in finding the mesiobuccal canal in all samples. Professionals <40, the magnification did not influence the location. Professionals >40, the magnification significantly influenced the location. In the direct vision, professionals >40 years located fewer canals than those <40 years of age with experience. In conclusion, these preliminary findings showed that when the microscope was used, the professionals with experience, regardless of age, found a higher number of canals. The use of the microscope was significant for professionals >40 years.

Evaluation of root canal morphology of maxillary premolars: a cone-beam computed tomography study.

The aim of this study was to evaluate the root canal configuration of maxillary premolars using cone-beam computed tomography (CBCT). CBCT images of 999 maxillary premolars from a database were analysed to determine the frequency of the number of roots, root canals and Vertucci's classification. The associations among these variables were evaluated by Chi-square test (P < 0.05). In the first premolars, 42.2% of single-rooted teeth had a type II configuration, whereas 98.7% of 2-rooted teeth showed type IV. In the second premolars, type I was the most prevalent (49.9%). The presence of two roots was more prevalent in first premolars, and the presence of one root was more prevalent in second premolars (P < 0.05). Male patients had a higher percentage of two roots compared with female patients (P < 0.05). Type IV and I was more prevalent in first and second premolars respectively (P < 0.05). There was a high frequency of 2-rooted and single-rooted teeth among maxillary first and second premolars respectively.

The use of auxiliary devices during irrigation to increase the cleaning ability of a chelating agent.

OBJECTIVES: This study investigated the cleaning ability of ultrasonically activated irrigation (UAI) and a novel activation system with reciprocating motion (EC, EasyClean, Easy Equipamentos Odontológicos) when used with a relatively new chelating agent (QMix, Dentsply). In addition, the effect of QMix solution when used for a shorter (1 minute) and a longer application time (3 minutes) was investigated. MATERIALS AND METHODS: Fifty permanent human teeth were prepared with K3 rotary system and 6% sodium hypochlorite. Samples were randomly assigned to five groups (n = 10) according to the final irrigation protocol: G1, negative control (distilled water); G2, positive control (QMix 1 minute); G3, QMix 1 minute/UAI; G4, QMix 1 minute/EC; G5, QMix 3 minutes. Subsequently the teeth were prepared and three photomicrographs were obtained in each root third of root walls, by scanning electron microscopy. Two blinded and pre-calibrated examiners evaluated the images using a four-category scoring system. Data were statistically analyzed using Kruskal-Wallis and Dunn tests (p < 0.05). RESULTS: There were differences among groups (p < 0.05). UAI showed better cleaning ability than EC (p < 0.05). There were improvements when QMix was used with auxiliary devices in comparison with conventional irrigation (p < 0.05). Conventional irrigation for 3 minutes presented significantly better results than its use for 1 minute (p < 0.05). CONCLUSIONS: QMix should be used for 1 minute when it is used with UAI, since this final irrigation protocol showed the best performance and also allowed clinical optimization of this procedure.

The effects of non-thermal plasma and conventional treatments on the bond strength of fiber posts to resin cement.

OBJECTIVES: This study compared the effect of hexamethyldisiloxane (HMDSO) and ammonia (NH3) plasmas on the bond strength of resin cement to fiber posts with conventional treatments. MATERIALS AND METHODS: Sixty-five fiber posts were divided into 5 groups: Control (no surface treatment); H2O2 (24% hydrogen peroxide for 1 min); Blasting (blasting with aluminum oxide for 30 sec); NH3 (NH3 plasma treatment for 3 min); HMDSO (HMDSO plasma treatment for 15 min). After the treatments, the Ambar adhesive (FGM Dental Products) was applied to the post surface (n = 10). The fiber post was inserted into a silicon matrix that was filled with the conventional resin cement Allcem Core (FGM). Afterwards, the post/cement specimens were cut into discs and subjected to a push-out bond strength (POBS) test. Additionally, 3 posts in each group were evaluated using scanning electron microscopy. The POBS data were analyzed by one-way analysis of variance and the Tukey's honest significant difference post hoc test (α = 0.05). RESULTS: The Blasting and NH3 groups showed the highest POBS values. The HMDSO group showed intermediate POBS values, whereas the Control and H2O2 groups showed the lowest POBS values. CONCLUSION: Blasting and NH3 plasma treatments were associated with stronger bonding of the conventional resin cement Allcem to fiber posts, in a procedure in which the Ambar adhesive was used.

Fracture Strength of Flared Root Canals Restored with Different Post Systems.

OBJECTIVE: To evaluate the fracture resistance of different intra-radicular post systems in flared root canals. METHODS: Sixty human canines were used. The coronal portion was removed and the root length was standardized at 17 mm. Canals were prepared and filled with gutta-percha/AH Plus sealer. Roots were embedded in self-polymerising acrylic resin blocks. According to the material used, the teeth were randomly divided into three groups (n=20): glass fibre post (GFP): GFP and Z350 resin composite core; pre-fabricated metal post (PMP): PMP and Z350 resin composite core; and cast metal core (CMC): CMC with silver-tin alloy. Coronal reconstruction involved fabrication of metal copings. Samples were submitted to mechanical compression testing at 45º in a universal test machine. Fracture pattern was evaluated under a stereoscope. The fracture strength values were submitted to one-way analysis of variance (ANOVA) and Tukey tests (α=0.05). RESULTS: There was no statistically significant difference between the resistance values among groups (P=0.193). With regard to fracture pattern, GFP showed 55% and PMP 45% of Type I fractures, which considered repairable or favourable, whereas MCC presented 50% of Type V, which was considered irreparable or unfavourable. CONCLUSION: Glass fibre and pre-fabricated metal posts have good fracture resistance to compression and may be used for restoring flared root canals, since they presented fractures mainly involving the filling core, thus facilitating later repair.

Effect of final irrigation protocols on push-out bond strength of an epoxy resin root canal sealer to dentin.

The purpose of the present study was to evaluate the effect of different final irrigation protocols on push-out bond strength of an epoxy resin root canal sealer to dentin. Eighty single-rooted anterior teeth were used. The root canals were partially prepared using a rotary system and the final diameter was standardised using a #5 Gates-Glidden drill prior to the push-out bond test. During chemomechanical preparation, 5.25% NaOCl or 2% CHX gel was used. For smear layer removal, 17% ethylenediaminetetraacetic acid (EDTA) or QMix 2 in 1 was applied for 3 min. As final irrigant, 1 mL of NaOCl, CHX solution or distilled water was used. On conclusion of preparation, canals were filled with gutta-percha/AH Plus sealer. Bond strength was measured by the push-out test. Data were statistically analysed by Kruskal-Wallis and Mann-Whitney U-tests. The group NaOCl/EDTA/NaOCl showed significantly higher bond strength values than other groups. In all groups, there were mainly mixed failure patterns. It can be concluded that 5.25% NaOCl proved to be the best solution for the final irrigation when combined with EDTA. The final irrigation protocols affect the push-out bond strength of AH Plus to dentin.

Efeito da desinfecção química nas uperfícies de guta-percha e Resilon / Effects of short-term chemical disinfection on gutta-percha and Resilon surfaces

Objetivo: Avaliar os efeitos das soluções de hipoclori-to de sódio 5,25% (NaOCl) e clorexidina 2% (CHX) na topografia e rugosidade de superfícies de guta-percha (GP) e Resilon (RE). Materiais e método: Superfícies pla-nas de guta-percha e Resilon foram utilizadas. Seis gru-pos foram avaliados: Controle GP (CGP) - guta-percha imersa em água destilada (AD) por 1 minuto; CHX GP (CHXGP) - guta-percha imersa em CHX por 1 minuto e em seguida lavada com AD; NaOCl GP (NGP) - guta--percha imersa em NaOCl por 1 minuto e em seguida lavada com AD; Controle RE (CR) - Resilon imerso em AD por 1 minuto; CHX RE (CHXR) - Resilon imerso em CHX por 1 minuto e em seguida lavado com AD; NaO-Cl RE (NR) - Resilon imerso em NaOCl por 1 minuto e em seguida lavado com AD. Microscopia eletrônica de varredura (MEV), Espectroscopia de energia dispersiva (EDS) e Perfilometria foram utilizadas para análise das amostras antes e após os tratamentos. Os valores de ru-gosidade obtidos por perfilomentria foram avaliados es-tatisticamente utilizando-se os testes de Kruskal-Wallis e Mann?Whitney (p < 0,05). MEV e EDS foram avaliados qualitativamente. Resultados: Os valores inicial e final de rugosidade foram respectivamente: CGP - 0,15 ± 0,02/ 0,15 ± 0,01; CHXGP ? 0,16 ± 0,02/ 0,15 ± 0,01; NGP ? 0,17 ± 0,01/ 0,16 ± 0,02; CR ? 0,16 ± 0,01/ 0,16 ± 0,01; CHXR ? 0,16 ± 0,01/ 0,16 ± 0,01 e NR ? 0,16 ± 0,01/ 0,16 ± 0,01. A análise estatística não revelou al-terações significativas nos valores de rugosidade após o uso de soluções para descontaminação. Adicionalmen-te, não foram observadas alterações na topografia e na composição química. Conclusão: A desinfecção quími-ca não causou alterações nas superfícies de guta-percha e Resilon.

Effect of in-office bleaching agents on the surface roughness and morphology of different dental composites: an AFM study.

The aim of this study was to evaluate, using atomic force microscopy, the effect of two different bleaching agents on the modification of dental composites materials. This modification will be judged by analyzing the variation of surface roughness and surface morphology of two different composites: one containing nanoparticles and other consisting of microhybrid resin. The bleaching was performed by using two different concentrations of hydrogen peroxide: HP Blue (20% hydrogen peroxide) and Whiteness HP Maxx (35% hydrogen peroxide). Disks of Esthet X and Filtek™ Z350 composites were used. Atomic force microscopy was used for analyses of the same place of the sample before and after treatment. A total of 12 analyses were performed per group (n = 12). The samples were analyzed qualitatively by evaluating morphological changes in the images and quantitatively by using roughness parameters (Ra). Data were analyzed statistically using Kruskal-Wallis, Mann-Whitney, and Friedman tests (P < 0.05). Changes were observed both qualitatively and quantitatively only in the groups where Esthet X resin was used. The use of hydrogen peroxide bleaching agents caused changes only in the surface of microhybrid composites, with no changes being observed in the composite containing nanoparticles. Despite being even significant, these alterations are clinically slight and can be eliminated by polishing them.

Evaluation of different irrigation protocols concerning the formation of chemical smear layer.

The aim of this work was to evaluate, by means of scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS), the different irrigation protocols concerning the formation of chemical smear layer (CSL). Fifty-five teeth were instrumented by using distilled water (DW) as irrigant. Next, the teeth were submitted to a protocol for removal of the mechanical smear layer produced. The teeth were divided into 11 groups, according to irrigation regimen. Then, the teeth were prepared and analyzed with SEM and EDS. Only in Group 1 [1 mL sodium hypochlorite (NaOCl) + 10 mL DW + 1 mL chlorhexidine (CHX) solution], Group 2 [1 mL NaOCl + 10 mL DW + 1 mL ethylenediaminetetraacetic acid (EDTA) + 10 mL DW + 1 mL CHX solution], and Group 3 [1 mL NaOCl + 10 mL DW + 1 mL citric acid (CA) + 10 mL DW + 1 mL CHX solution], the formation of CSL was observed. In the groups where CHX gel was used alone or in association with EDTA, CA, phosphoric acid (PA), and CHX solution, no formation of CSL was observed. According to the results found in the cases in which one wants to associate NaOCl with CHX, the protocol using PA (1 mL NaOCl + 10 mL DW + 1 mL PA + 10 mL DW + 1 mL CHX solution) did not induce formation of CSL.

The multidisciplinary management of avulsed teeth: a case report.

This paper reports multidisciplinary treatment of a dental trauma case to achieve a favorable prognosis. A healthy 14-year-old girl reported avulsion of teeth 11 and 21 which had occurred three months earlier. The initial treatment consisting of replantation with a semi-rigid splint was performed in hospital. At presentation, the patient was still using the semi-rigid splint. The clinical examination revealed the presence of increased mobility in teeth 11 and 21, and absence of vitality in both. Radiographic examination showed the presence of inflammatory external root resorption in both teeth. The treatment proposed consisted of teeth extraction, a temporary prosthesis followed by adhesive prosthesis, and finally, implant surgery associated with porcelain crowns.

Effect of disinfection solutions on the adhesion force of root canal filling materials.

INTRODUCTION: Sodium hypochlorite (NaOCl) and chlorhexidine (CHX) are usually used to disinfect gutta-percha (GP) and Resilon (Res) cones. This study investigated the adhesion force (Fad) between root canal sealers and GP and Res cones following different disinfection protocols by using atomic force microscopy. METHODS: Nine flat surfaces of each material were obtained with medium points of GP and Res. The samples were divided into 6 groups (n = 3): control group GP, immersion in distilled water (DW); NaOCl group GP, immersion in 5.25% NaOCl and then washing with DW; CHX group GP, immersion in 2% CHX and then washing with DW; control group Res, immersion in DW; NaOCl group Res, immersion in 5.25% NaOCl and then washing with DW; and CHX group Res, immersion in 2% CHX and then washing with DW. Atomic force microscopy tips containing AH Plus sealer were used to obtain force versus distance curves regarding GP surfaces. Fad was calculated from the force curves. The same procedure was performed with Real Seal SE and Res surfaces. Data were statistically analyzed. RESULTS: A higher Fad between solid filling materials (GP and Res) and root canal sealers was found when CHX solution was used. Treatment with NaOCl solution did not show influence on the Fad values. CONCLUSIONS: The decontamination of GP and Res with 2% CHX resulted in higher Fad values. The use of CHX in the disinfection process of GP and Res cones might be a better option before root canal obturation.

Comparison between the effect of plasma and chemical treatments on fiber post surface.

INTRODUCTION: The aim of the present study was to evaluate the fiber post surface after plasma and usual treatments and the adhesion between treated fiber posts and Rely X Unicem resin cement (3M ESPE, St Paul, MN). METHODS: Flat fiber posts were divided into 6 groups according to surface treatment: silane, hydrofluoric acid, hydrofluoric acid plus silane, plasma polymerization with argon, ethylenediamine plasma (EDA), and the control group. A goniometer was used to measure the contact angle between the groups with water or resin cement. Scanning electron microscopy and electron dispersive spectroscopy were used to examine the topography and chemical changes in the post surfaces after treatment. Push-out tests were performed using a universal testing machine to evaluate the adhesion strength between treated fiber posts and resin cement. RESULTS: In the contact angle with water, the most hydrophilic surface was observed in samples treated with argon plasma, followed by treatments with silane and hydrofluoric acid plus silane. The hydrophobic characteristic was observed with EDA and hydrofluoric acid. The contact angle with dual resin cement showed lower values with argon and EDA, followed by silane and hydrofluoric acid plus silane. Electron dispersive spectroscopy analyses showed chemical modifications in the surface after different treatments although topographic changes were verified only with EDA plasma compared with the control. Push-out results did not show differences between groups compared with the control, except for EDA plasma treatment. CONCLUSIONS: Plasma treatment favored the wettability of the post surface by modifying it chemically. Adhesion improvement was only observed after EDA treatment.