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Human Third Molars (human + third_molar)
Selected AbstractsDentin surface treatment using a non-thermal argon plasma brush for interfacial bonding improvement in composite restorationEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2010Andy C. Ritts Ritts AC, Li H, Yu Q, Xu C, Yao X, Hong L, Wang Y. Dentin surface treatment using a non-thermal argon plasma brush for interfacial bonding improvement in composite restoration. Eur J Oral Sci 2010; 118: 510,516. © 2010 Eur J Oral Sci The objective of this study was to investigate the treatment effects of non-thermal atmospheric gas plasmas on dentin surfaces used for composite restoration. Extracted unerupted human third molars were prepared by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. The dentin surfaces were treated using a non-thermal atmospheric argon plasma brush for various periods of time. The molecular changes of the dentin surfaces were analyzed using Fourier transform infrared spectrophotometry/attenuated total reflectance (FTIR/ATR), and an increase in the amount of carbonyl groups was detected on plasma-treated dentin surfaces. Adper Single Bond Plus adhesive and Filtek Z250 dental composite were applied as directed. To evaluate the dentin/composite interfacial bonding, the teeth thus prepared were sectioned into micro-bars and analyzed using tensile testing. Student,Newman,Keuls tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s of plasma treatment. However, the bonding strength to plasma-treated inner dentin did not show any improvement. It was found that plasma treatment of the peripheral dentin surface for up to 100 s resulted in an increase in the interfacial bonding strength, while prolonged plasma treatment of dentin surfaces (e.g. 5 min) resulted in a decrease in the interfacial bonding strength. [source] Influence of the pulpal components on human dentine permeability in vitroINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2005P. Puapichartdumrong Abstract Aim, To examine the influence of the retained pulpal components on permeability of human dentine by monitoring drug diffusion. Methodology, Twelve intact dentine discs were prepared from freshly extracted human third molars. The dentine surface on the enamel side was etched with 10% polyacrylic acid for 30 s. The drug diffusion test was carried out before and after removal of the retained pulpal components. Each dentine disc was inserted between two plastic chambers; enamel- and pulpal-side chambers, which were filled with 0.05 mol L,1 naproxen sodium (NA) and phosphate-buffered saline (PBS), respectively. After 10 min, the solution on the pulpal-side chamber was collected to determine the concentration of NA using a spectrophotometer. To remove the retained pulpal components and residual NA, the pulp chamber of each disc was washed out with PBS and placed in an ultrasonic cleaner. After removal of these components and the residual NA, the drug diffusion test was repeated. The inner surface of the pulp chamber was observed using scanning electron microscopy (SEM) before and after the removal of the retained pulpal components. Results, The amount of NA that diffused through dentine into the pulp was significantly higher after the pulp chamber was washed out with PBS (paired t -test, P < 0.05). SEM observation demonstrated the presence of the retained pulpal components, odontoblastic layer and some parts of subodontoblastic zone, covering the surface of predentine. These components were removed after the pulp chamber was washed out with PBS followed by cleaning in an ultrasonic cleaner. Conclusions, The presence of retained pulpal components had a significant influence on drug diffusion through dentine discs. [source] Effect of curing mode on bond strength of self-adhesive resin luting cements to dentinJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2010T. R. Aguiar Abstract In this study, the in vitro bond strength of dual-curing resin cements to indirect composite restorations when the cement was either light polymerized or allowed to only autopolymerize was evaluated. Occlusal dentin surfaces of 56 extracted human third molars were flattened to expose coronal dentin. Teeth were assigned to eight groups (n = 7) according to resin cement products and polymerization modes: conventional cement (Panavia F 2.0; Kuraray Medical) and self-adhesive cements [RelyX Unicem (3M ESPE), BisCem (Bisco), and G-Cem (GC Corp.)]. Cements were applied to prepolymerized resin discs (2-mm-thick Sinfony; 3M ESPE), which were subsequently bonded to the prepared dentin surfaces. The restored teeth were either light-polymerized through the overlying composite according to manufacturers' instructions or were allowed to only self-cure. After 24 h, the teeth and restorations were sectioned to obtain multiple bonded beams (1.0 mm2) and tested in tension at a crosshead speed of 0.5 mm/min until failure. Data (MPa) were analyzed by two-way ANOVA and Tukey test (, = 0.05). Light activation of some cement systems (G-Cem and Panavia F 2.0) increased the bond strength, while the curing mode did not affect the bond strength for some (RelyX Unicem and BisCem). The bond strength in the autopolymerized mode varied among products. In general, the use of self-adhesive resin cements did not provide significantly higher bond strengths than that of a conventional material, and two self-adhesive cements yielded significantly lower bond values (regardless of cure mode) than the other products. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010 [source] Scanning Electron Microscope Analysis of Internal Adaptation of Materials Used for Pulp Protection under Composite Resin RestorationsJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2005MARIA INEZ LEMOS PELIZ DDS ABSTRACT Purpose:: The aim of this study was to evaluate the interfacial microgap with different materials used for pulp protection. The null hypothesis tested was that the combination of calcium hydroxide, resin-modified glass ionomer, and dentin adhesive used as pulp protection in composite restorations would not result in a greater axial gap than that obtained with hybridization only. Materials and Methods: Standardized Class V preparations were performed in buccal and lingual surfaces of 60 caries-free, extracted human third molars. The prepared teeth were randomly assessed in six groups: (1) Single Bond (SB) (3M ESPE, St. Paul, MN, USA); (2) Life (LF) (Kerr Co., Romulus, MI, USA) + SB; (3) LF + Vitrebond (VT) (3M ESPE) + SB; (4) VT + SB; (5) SB + VT; (6) SB + VT + SB. They were restored with microhybrid composite resin Filtek Z250 (3M ESPE), according to the manufacturer's instructions. However, to groups 5 and 6, the dentin bonding adhesive was applied prior to the resin-modified glass ionomer. The specimens were then thermo-cycled, cross-sectioned through the center of the restoration, fixed, and processed for scanning electron microscopy. The specimens were mounted on stubs and sputter coated. The internal adaptation of the materials to the axial wall was analyzed under SEM with × 1,000 magnification. Results: The data obtained were analyzed with nonparametric tests (Kruskal-Wallis, p V .05). The null hypothesis was rejected. Calcium hydroxide and resin-modified glass ionomer applied alone or in conjunction with each other (p < .001) resulted in statistically wider microgaps than occurred when the dentin was only hybridized prior to the restoration. [source] Tensile bond strengths of four different dentin adhesives on irradiated and non-irradiated human dentin in vitroJOURNAL OF ORAL REHABILITATION, Issue 9 2001C. R. Gernhardt This study evaluated the influence of irradiation on dentin bond strength. Sixty irradiated and 60 non-irradiated human third molars were used. The irradiation dose of 60 Gy was fractionally applied over 6 weeks (2 Gy day,1, 5 days week,1). All teeth were prepared in a special manner allowing the simulation of intra-pulpal pressure and dentin perfusion. Dentin specimens with a thickness of 2·0 mm were obtained under standardized conditions. The specimens were randomly assigned to four experimental groups. Tensile bond strength of four different dentin bonding agents (ScotchbondŌ 1, Solobond Plus®, Prime&BondŌ 2·1 and Syntac®) was evaluated using an Instron Universal testing machine. Pairwise comparison did not show any significant differences between the irradiated and non-irradiated groups. The influence of the different dentin adhesives was significant (P=0·0001; ANOVA). Compared with Solobond Plus® and Prime&BondŌ 2·1, the use of ScotchbondŌ 1 resulted in a significantly higher tensile bond strength in non-irradiated specimen (P< 0·05; closed test procedure based on Kruskal,Wallis test). Within the limitations of an in vitro study, it can be concluded that adhesive restoration procedures can be successfully used in patients irradiated for cancer of the head and neck. [source] Micromorphology of resin,dentin interfaces using one-bottle etch&rinse and self-etching adhesive systems on laser-treated dentin surfaces: A confocal laser scanning microscope analysisLASERS IN SURGERY AND MEDICINE, Issue 7 2010Marcelo Tavares de Oliveira DDS Abstract Background and Objectives This study evaluated the hybrid layer (HL) morphology created by three adhesive systems (AS) on dentin surfaces treated with Er:YAG laser using two irradiation parameters. Study Design Occlusal flat dentin surfaces of 36 human third molars were assigned into nine groups (n,=,4) according to the following ASs: one bottle etch&rinse Single Bond Plus (3M ESPE), two-step Clearfil Protect Bond (Kuraray), and all-in-one S3 Bond (Kuraray) self-etching, which were labeled with rhodamine B or fluorescein isothiocyanate,dextran and were applied to dentin surfaces that were irradiated with Er:YAG laser at either 120 (38.7,J/cm2) or 200,mJ/pulse (64.5,J/cm2), or were applied to untreated dentin surfaces (control group). The ASs were light-activated following MI and the bonded surfaces were restored with resin composite Z250 (3M ESPE). After 24,hours of storage in vegetable oil, the restored teeth were vertically, serially sectioned into 1-mm thick slabs, which had the adhesive interfaces analyzed with confocal laser microscope (CLSM,LSM 510 Meta). CLSM images were recorded in the fluorescent mode from three different regions along each bonded interface. Results Non-uniform HL was created on laser-irradiated dentin surfaces regardless of laser irradiation protocol for all AS, while regular and uniform HL was observed in the control groups. "Stretch mark"-like red lines were found within the HL as a result of resin infiltration into dentin microfissures, which were predominantly observed in 200,mJ/pulse groups regardless of AS. Poor resin infiltration into peritubular dentin was observed in most regions of adhesive interfaces created by all ASs on laser-irradiated dentin, resulting in thin resin tags with neither funnel-shaped morphology nor lateral resin projections. Conclusion Laser irradiation of dentin surfaces at 120 or 200,mJ/pulse resulted in morphological changes in HL and resin tags for all ASs evaluated in the study. Lasers Surg. Med. 42:662,670, 2010. © 2010 Wiley-Liss, Inc. [source] Brief communication: Dental development and enamel thickness in the Lakonis Neanderthal molarAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009T.M. Smith Abstract Developmental and structural affinities between modern human and Neanderthal dental remains continue to be a subject of debate as well as their utility for informing assessments of life history and taxonomy. Excavation of the Middle Paleolithic cave site Lakonis in southern Greece has yielded a lower third molar (LKH 1). Here, we detail the crown development and enamel thickness of the distal cusps of the LKH 1 specimen, which has been classified as a Neanderthal based on the presence of an anterior fovea and mid-trigonid crest. Crown formation was determined using standard histological techniques, and enamel thickness was measured from a virtual plane of section. Developmental differences include thinner cuspal enamel and a lower periodicity than modern humans. Crown formation in the LKH 1 hypoconid is estimated to be 2.6,2.7 years, which is shorter than modern human times. The LKH 1 hypoconid also shows a more rapid overall crown extension rate than modern humans. Relative enamel thickness was approximately half that of a modern human sample mean; enamel on the distal cusps of modern human third molars is extremely thick in absolute and relative terms. These findings are consistent with recent studies that demonstrate differences in crown development, tissue proportions, and enamel thickness between Neanderthals and modern humans. Although overlap in some developmental variables may be found, the results of this and other studies suggest that Neanderthal molars formed in shorter periods of time than modern humans, due in part to thinner enamel and faster crown extension rates. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||