Qualitative and quantitative assessment of the potential effect of cigarette smoking on enamel of human smokers' teeth.

OBJECTIVE: This study aimed to examine the potential changes in enamel surface of human smokers' teeth. MATERIALS AND METHODS: Forty extracted permanent, human, noncarious anterior teeth were used in this study. Half of these teeth were obtained from heavy smokers, while the other half of teeth were collected from nonsmokers (control teeth). The teeth were then subjected for scanning electron microscopic examination together with energy dispersive X ray and micro-hardness analysis to evaluate the qualitative and quantitative effect of smoking respectively. RESULTS: SEM of smokers' teeth showed variable degrees of destruction from small areas of demineralization as holes and pits to destruction and deterioration of the organizational pattern of the rod substance. Moreover, areas of defective remineralization were detected. The microhardness, calcium and phosphorus weight % significantly decreased whereas the Ca/P ratio was significantly increased. CONCLUSION: Cigarette smoking adversely affected the ultrastructure and mechanical properties of enamel and even hindered the normal remineralization process thus cigarette smoking cessation should be promoted in the dental office daily practices.

Assessment of remineralization potential of Theobromine and Sodium Fluoride gels on Artificial Caries like lesions / Avaliação do potencial de remineralização de géis de teobromina e fluoreto de sódio em lesões de cárie artificial

Objective: To compare the remineralization potential of theobromine and sodium fluoride gels on artificial caries like lesion. Materials and Methods: Forty longitudinal halves of human mandibular premolars were equally divided into 4 groups of 10 samples each: control group (C), samples were stored in distilled water during the experiment period. The remaining 30 specimens were subjected to demineralization protocol to create caries like lesions. samples were immersed for three days in a demineralization solution (pH 5.0) containing 0.2% carbopol and 0.1% lactic acid saturated with calcium phosphate tribasic. The samples were subdivided into 3 equal groups according to the treatment applied during the pH cycle. Demineralization group "D": no treatment applied. Group "F" treated with 2000 mg/liter sodium fluoride gel. Group "T" treated with 200 mg/liter theobromine gel. The specimens of the two studies groups were subjected to Demineralization- Remineralization PH Cycle Protocol for 5 days (Alternating four steps: 1: Treatment material, fluoride or theobromine ˜= 3 minutes. 2: Demineralizing solution 3 hours. 3: treatment material ˜= 3 minutes. 4: Remineralizing solution till the next cycle). The samples were investigated by scanning electron microscope (SEM) and energy dispersive x-ray analysis (EDXA). Results: The enamel of the demineralization group was porous with artificial caries like changes exposing the subsurface enamel rods with severe rod core defects. Theobromine gel and fluoride gel groups showed marked improvement in the surface characteristics in the enamel in both groups. Theobromine gel group showed more observable enamel surface improvement than the fluoride gel group. EDXA revealed that the calcium-phosphorus ratio displayed a descending order: (C > T > F > D). The differences between the two tested groups were not statistically significant. Conclusion: Theobromine gel had more effective remineralizing potential than fluoride gel as a result of its effect in improving the enamel surface characteristics of human teeth. (AU)

Objetivo: Comparar o potencial de remineralização dos géis de teobromina e fluoreto de sódio em lesões de cáries artificiais. Materiais e Métodos: Quarenta metades longitudinais de pré-molares inferiores humanos foram igualmente divididas em 4 grupos de 10 amostras cada: grupo controle (C), as amostras foram armazenadas em água destilada durante o período do experimento. As 30 amostras restantes foram submetidas ao protocolo de desmineralização paracriar lesões artificiais de cárie. As amostras foram imersas por três dias em uma solução de desmineralização (pH 5,0) contendo 0,2% de carbopol e 0,1% de ácido lático saturado com fosfato de cálcio tribásico. As amostras foram subdivididas em 3 grupos iguais, de acordo com o tratamento aplicado durante o ciclo do pH. Grupo de desmineralização "D": nenhum tratamento aplicado. Grupo "F" tratado com 2000 mg / litro de fluoreto de sódio em gel. Grupo & quot;T &q uot; tratado com 200 mg / litro de gel de teobromina. As amostras dos dois grupos de estudo foram submetidas ao protocolo de ciclo de desmineralização - remineralização por 5 dias (quatro etapas alternativas: 1: material de tratamento, flúor ou teobromina ˜= 3 minutos. 2: solução desmineralizante 3 horas. 3: material de tratamento ˜= 3 minutos 4: Solução de remineralização até o próximo ciclo). As amostras foram investigadas por microscopia eletrônica de varredura(MEV) e análise de raios-x dispersivos de energia (EDXA). Resultados: O esmalte do grupo de desmineralização era poroso, com cáries artificiais, como alterações que expunham as hastes de esmalte do subsolo com graves defeitos no núcleo da haste. Os grupos gel de teobromina e flúor apresentaram melhora acentuada nas características da superfície do esmalte nos dois grupos. O grupo gel de teobromina mostrou uma melhoria na superfície do esmalte mais observável do que o grupo gel de fluoreto. A EDXA revelou que a razão cálcio-fósforo exibia uma ordem decrescente: (C> T> F> D). As diferenças entre os dois grupos testados não foram estatisticamente significantes. Conclusão: O gel de teobromina teve um potencial remineralizante mais eficaz que o gel de flúor como resultado de seu efeito na melhoria das características da superfície do esmalte dos dentes humanos. (AU)

Assessment of microcracks and shear bond strength after debonding orthodontic ceramic brackets on enamel priorly etched by different Er,Cr:YSGG and Er:YAG laser settings without acid application: An in vitro study.

BACKGROUND DATA: Enamel microcrack formation has a high incidence after mechanical debonding of ceramic brackets. This may be due to high delivered shear bond strength values when enamel is priorly etched by phosphoric acid. It is still not well elucidated in the literature if laser etching affects enamel the same way. The aim of the research was to analyze different Er,Cr:YSGG and Er:YAG laser etching settings as an alternative to phosphoric acid, in an attempt to prevent enamel microcrack formation during laser etching and mechanical debonding, while reducing the shear bond strength to the minimal clinical acceptable value. MATERIALS AND METHODS: One hundred and thirty-three teeth were randomly divided into 7 experimental groups according to their etching modalities. Settings used for enamel etching were in Er,Cr:YSGG groups: Er,Cr:YSGG (1.5Watt, W/20Hertz, Hz); Er,Cr:YSGG (1.5W/15Hz) and Er,Cr:YSGG (2W/20Hz) and settings used for enamel etching in Er:YAG groups were: Er:YAG (60 millijoules, mJ), Er:YAG (80mJ) and Er:YAG (100mJ). Group C etched with 37% phosphoric acid served as control. Microscopic analysis was performed to assess presence of enamel microcracks. Shear bond strength was evaluated after thermocycling using Weibull survival analysis. RESULTS: All groups showed a reduction in additional microcracks after debonding when compared to control, but only group Er:YAG (60mJ) exhibited a statistically significant difference. Groups Er:YAG (80mJ), control and Er:YAG (100mJ) showed respectively the highest probability of survival at various stress levels followed by groups Er:YAG (60mJ); Er,Cr:YSGG (1.5W/15Hz); Er,Cr:YSGG (2W/20Hz) and Er,Cr:YSGG (1.5W/20Hz) that presented a relatively considerable risk of failure, even at low stress levels. CONCLUSIONS: When considering reduction of enamel microcrack formation and clinical acceptable shear bond strength, none of the groups succeeded both. Etching by Er:YAG (60mJ) and Er,Cr:YSGG (1.5W/15Hz), showed the least overall microcrack incidence between groups, but Er:YAG (60mJ) displayed significant reduction compared to phosphoric acid. However, etching by Er:YAG (80mJ) had the most predictable results in term of shear bond strength.

A novel electron-microscopic method for measurement of mineral content in enamel lesions.

OBJECTIVE: To assess Scanning Electron Microscopy in Back-Scattered Emission mode (BSE-SEM) for measurement of lesion mineral content as a function of depth. Direct comparison is made with Transverse Micro-Radiography (TMR) and Surface Micro-Hardness (SMH) on carious and erosive lesions. DESIGN: Caries lesions prepared from sound bovine enamel at 37 °C and pH 4.6 in unsaturated (7d) or part-saturated (8d, 4.1 mM Ca2+, 8 mM Pi) lactic acid /methyl cellulose gel system, followed by TMR analysis. Erosive lesions prepared from sound bovine enamel (1% citric acid, pH3.8, room temperature) for 5, 10, 15 or 20 min at n = 10 per treatment group. SMH readings (Vickers diamond, 1.9 N, 20 s) were taken from acid-treated and reference areas of each sample. BSE-SEM performed on polished cross-sections of lesioned samples (Jeol JSM6490LV SEM; high vacuum, 10 keV beam voltage, magnification x500 with constant working distance of 10 mm). Under identical SEM conditions, polished standards i.e. MgF2, alumina, Mg, Al and Si provided a calibration plot of BSE-SEM signal vs. atomic number (z¯). Mineral content vs. depth plots were derived from the cross-sectional BSE-SEM data. RESULTS: Cross-sectional BSE-SEM images clearly differentiate between caries and erosive lesions. Comparison of caries lesion mineral loss from BSE-SEM with TMR data showed good correlation (R2 = 0.98). Similarly, comparison of BSE-SEM data from erosive lesions showed good correlation (R2 = 0.99) with hardness loss data from SMH. CONCLUSION: BSE-SEM provides a relatively rapid and cost-effective method for the assessment of mineral content in demineralised tooth enamel and is applicable to both caries and erosive lesions.

Topographic assessment of human enamel surface treated with different topical sodium fluoride agents: Scanning electron microscope consideration.

INTRODUCTION: Continuous balanced demineralization and remineralization are natural dynamic processes in enamel. If the balance is interrupted and demineralization process dominates, it may eventually lead to the development of carious lesions in enamel and dentine. Fluoride helps control decay by enhancing remineralization and altering the structure of the tooth, making the surface less soluble. METHODOLOGY: One hundred and twenty sound human permanent incisors randomly and equally distributed into six groups as follows: Group I - Control, II - Sodium fluoride solution, III - Sodium fluoride gel, IV - Sodium fluoride varnish, V - Clinpro Tooth Crème (3M ESPE), and VI-GC Tooth Mousse Plus or MI Paste Plus. The samples were kept in artificial saliva for 12 months, and the topical fluoride agents were applied to the respective sample groups as per the manufacturer instructions. Scanning electron microscope (SEM) evaluation of all the samples after 6 and 12 months was made. RESULTS: Morphological changes on the enamel surface after application of fluoride in SEM revealed the presence of globular precipitate in all treated samples. Amorphous, globular, and crystalline structures were seen on the enamel surface of the treated samples. Clear differences were observed between the treated and untreated samples. CONCLUSION: Globular structures consisting of amorphous CaF2precipitates, which acted as a fluoride reservoir, were observed on the enamel surface after action of different sodium fluoride agents. CPP-ACPF (Tooth Mousse) and Tricalcium phosphate with fluoride (Clinpro tooth crème) are excellent delivery vehicles available in a slow release amorphous form to localize fluoride at the tooth surface.

Assessment of Enamel Bond Strength of Hypoplastic Primary Teeth.

PURPOSE: The purpose of this study was to compare the enamel bond strength of hypoplastic and healthy primary teeth. METHODS: Twenty-five hypoplastic teeth (experimental group) and 25 healthy primary teeth (control group) were selected and conditioned with 35 percent orthophosphoric acid before a two-layer adhesive system (Single Bond) was applied. Composite resin (Filtek Z350) was inserted in a single application, two-mm high and one-mm in diameter, and then light-cured for 20 seconds. After being stored in distilled water for 24 hours, the specimens were submitted to a shear bond strength test. Fractures were analyzed under a stereomicroscope. RESULTS: No significant differences in bond strength were observed between the experimental group (70.27±20.40 MPa) and control group (67.84±23.37 MPa; P>0.05). However, adhesive fractures were more frequently observed in healthy teeth (72 percent) while hypoplastic teeth presented mixed fractures (60 percent) and enamel cohesive fractures (36 percent). CONCLUSIONS: The shear bond strength of the enamel of hypoplastic primary teeth was similar to that of healthy teeth. However, distinct characteristics were observed in the dental samples following fracture.

Ultrasonic assessment of the effects of self-assembling peptide scaffolds on preventing enamel demineralization.

OBJECTIVES: This study evaluates the effect of self-assembling peptide P11-4 (Curodont Repair, CDR) on bovine enamel remineralization by measuring changes in ultrasonic propagation velocity. METHODS: Six specimens per group were prepared by sectioning bovine teeth into enamel blocks. These blocks were then immersed in lactic acid buffer solution (pH = 4.75) for 10 min twice a day and stored in artificial saliva. Other specimens were first treated with CDR, followed by a 10-min immersion in the lactic acid buffer solution twice a day, before storage in artificial saliva. The propagation time of longitudinal ultrasonic waves was measured using a pulser/receiver. Six specimens were used for each treatment protocol. The obtained data were statistically analyzed using ANOVA followed by Tukey's honestly significant difference tests (α = 0.05). Specimens were observed using laser scanning microscopy and scanning electron microscopy. RESULTS: Sonic velocity was found to decrease with time for specimens stored in the demineralizing solution. On the other hand, increases in sonic velocity were found for specimens treated with CDR. These specimens also exhibited signs of mineral deposition. CONCLUSIONS: By measuring the ultrasonic propagation velocity, it can be concluded that CDR application has an ability to promote bovine enamel remineralization.

Effects of sandblasting before orthophosphoric acid etching on lingual enamel: in-vitro roughness assessment.

INTRODUCTION: In this study, we evaluated changes in lingual enamel roughness due to sandblasting with 27-, 50-, and 90-µm aluminum oxide particles followed by 37% orthophosphoric acid etching. METHODS: Twenty-four maxillary premolars were included in the study. The lingual enamel roughness of 20 teeth was evaluated using a laser confocal microscope before and after enamel conditioning. Group 1 (control) was etched with 37% orthophosphoric acid; groups 2, 3, and 4 were sandblasted with 27-, 50-, and 90-µm aluminum oxide particles, respectively, before acid etching. The lingual surfaces of the other 4 teeth were evaluated using scanning electron microscopy after they had received one of the conditioning methods under study. Paired t tests were used to compare the roughness parameters obtained before and after conditioning in each group, and 1-way analysis of variance was used to compare the surface roughness between groups. The significance level was set at 5% for all statistical analyses. RESULTS: The 4 conditioning methods significantly increased the roughness of the lingual enamel. However, the roughness increases in the groups that were sandblasted with 27-, 50-, and 90-µm aluminum oxide particles before orthophosphoric acid etching were statistically greater than was the increase in the group conditioned only with orthophosphoric acid. Scanning electron microscopy showed different conditioning patterns among specimens that were conditioned only with orthophosphoric acid and those sandblasted with aluminum oxide before acid etching. CONCLUSIONS: Lingual enamel conditioning with aluminum oxide sandblasting before acid etching results in greater roughness and produces a conditioning pattern different from that of acid etching alone.

In vivo scanning electron microscope assessment of enamel permeability in primary teeth with and without early childhood caries.

BACKGROUND: Over the years, certain primary teeth have been shown to be highly sensitive to dental caries, while others have remained caries-free. It has been hypothesized that this may be attributed to differences in the permeability of the enamel surface. AIM: The aim of the study was to evaluate the hypothesized differences in the permeability of primary tooth enamel in children with and those without Severe Early Childhood Caries (S-ECC) using scanning electron microscopy. MATERIALS AND METHODS: Sixteen children between 3 and 6 years of age were randomly selected and divided into two groups: Group 1, children without S-ECC (n = 8), and Group 2, children with S-ECC (n = 8). In each child, 4 teeth (the maxillary right and left central and lateral incisors) were subjected to evaluation. An impression was made with polyvinylsiloxane impression material, and scanning electron microscopy was used to inspect the negative replicas for droplets. RESULTS: The results indicated higher significance when individual regions (cervical, middle, and incisal thirds) in the two groups were evaluated and compared. Similarly, the overall results showed high statistical significance between S-ECC and non-S-ECC teeth. CONCLUSION: There could be a positive relationship between the permeability of tooth enamel and the development of caries, which needs further research.

Nanoscratch testing for the assessment of enamel demineralization under conditions simulating wine erosion.

BACKGROUND: Erosive tooth wear and dentinal hypersensitivity are common problems affecting professional wine tasters. By using nanoscratch testing, the aim of this in vitro study was to assess enamel softening under conditions simulating 10 one-minute episodes of wine erosion. METHODS: Ten enamel specimens were bathed in artificial saliva for 2 hours before being eroded for 10 episodes, with each episode comprising one minute of wine erosion followed by one minute of remineralization in artificial saliva. Nanoscratches were placed with a spherical tip (20 µm radius) in a nanoindenter under a load of 100 mN at baseline (stage 1), after a one-erosion episode (stage 2) and after 10-erosion episodes (stage 3). RESULTS: There were significant effects of erosion stages on both scratch depth (p<0.001) and surface roughness (p<0.001). Post hoc tests showed significant differences in both scratch depths and surface roughness between stages 1 and 3 (p<0.001), and between stages 2 and 3 (p<0.01). CONCLUSIONS: Enamel softening occurs at an early stage of wine tasting, emphasizing the need to implement early preventive strategies in professional wine tasters. Further research elucidating the fundamental mechanisms involved in early stages of erosion has the potential to lead to development of more effective preventive strategies.

In vitro assessment of the acid resistance of demineralized enamel irradiated with Er, Cr:YSGG and Nd:YAG lasers.

PURPOSE: This study's purpose was to evaluate the acid resistance of demineralized enamel irradiated with high-intensity lasers. METHODS: Enamel fragments were demineralized and treated as follows (N=10): Group 1-no treatment; Group 2-five percent sodium fluoride (NaF) varnish; Group 3-Er, Cr:YSGG laser (8.92 J/cm2, 0.5 W, 20 Hz, 30 seconds); Group 4-NaF and Er, Cr:YSGG laser; Group 5-Er, Cr:YSGG laser and NaF; Group 6-Nd:YAG laser (84.9 J/cm2, 0.5 W, 10 Hz, 30 seconds); Group 7-NaF and Nd:YAG laser; and Group 8-Nd:YAG laser and NaF. The samples were subjected to pH-cycling and assessed by microhardness (analysis of variance; α equals five percent) at different depths from the outer enamel surface. Samples were observed using polarized light microscopy (PLM) and scanning electron microscopy (SEM). RESULTS: There were no significant differences among the experimental groups in any of the subsurface layers evaluated. PLM observation revealed that the extent of demineralization of the irradiated samples was similar to the samples for Group 1 (control). SEM observation showed that irradiated surfaces were ablated and presented areas of melting. CONCLUSIONS: Laser irradiation, with or without applying five percent sodium fluoride, was not capable of increasing the enamel white spot lesions' acid resistance.

Three-dimensional profilometric assessment of early enamel erosion simulating gastric regurgitation.

OBJECTIVES: A priority research area in minimal intervention dentistry is the characterization of the early stages of dental erosion. The aim of this in vitro study was to assess the effect of short, repetitive erosive challenges to human enamel over 2 min at pH 1.5 and 3.0 under conditions simulating gastric regurgitation. METHODS: Enamel surfaces were subjected to erosive challenges at pH 1.5 (Group 1, n=10) and pH 3.0 (Group 2, n=9) for periods of 30s (stage 1), 60s (stage 2) and 120 s (stage 3). Quantitative changes were assessed longitudinally by measuring the 3D average surface roughness (Sa) values using 3D confocal microscopy. Qualitative micrographic assessment of surface changes was also conducted by using environmental scanning electron microscopy. RESULTS: Linear mixed model analysis showed significant effects of the pH values (p<0.001) and the stages (p<0.001) on the observed Sa values. Post hoc tests showed significant increases in the Sa values between baseline and other stages in both groups (p<0.01). The mean Sa values also increased significantly from stage 1 to stage 2 in Group 1 (p<0.05). Micrographic analysis displayed severely etched enamel rods in Group 1, but only subtle changes in Group 2. CONCLUSIONS: The complexity of the enamel surface is influenced by both acid concentration (pH value) and duration of acid exposure during early stages of erosion. Erosion occurring under conditions simulating GORD can be detected in its initial stages, opening up the possibilities of early diagnosis and management of this condition. CLINICAL SIGNIFICANCE: Erosive tooth wear occurs progressively and insidiously, often creating complex treatment challenges. This emphasizes the need for early diagnosis and management in accordance with minimal intervention philosophy. Our findings provide a foundation for further research that could lead to the development of highly-sensitive clinical diagnostic tools and preventive strategies.

Assessment of Er:YAG laser for cavity preparation in primary and permanent teeth: a scanning electron microscopy and thermographic study.

PURPOSE: Most studies of cavity preparation using Er:YAG lasers have employed permanent teeth. This study's purpose was to compare the cutting efficiency of an Er:YAG laser versus diamond burs in primary and permanent teeth in order to measure thermal effects on the pulp and evaluate lased surfaces using scanning electron microscopy (SEM). METHODS: A total of 80 primary and permanent teeth were used. Crater depths and mass loss were measured after delivering laser pulses at varying energies onto sound or carious enamel or dentin using the Key-3 laser. Control samples were cut using diamond burs in an air turbine handpiece. Thermal changes were measured using miniature thermocouples placed into the pulp chamber. Lased surfaces were evaluated using SEM. RESULTS: Laser ablation crater-like defects were deeper in dentin than enamel at the same pulse energy. Greater ablation rates for dentin and enamel and significantly more efficient removal of carious tooth structure by laser was present in primary teeth. Temperature rises in the pulp did not exceed the 5.5 degrees Celsius threshold in any teeth during laser ablation. CONCLUSIONS: The Er:YAG laser is an efficient device for cavity preparations in primary teeth, with no unacceptable increases in temperature detected in this model.

In vitro assessment of artificial saliva formulations on initial enamel erosion remineralization.

OBJECTIVES: Various formulations of artificial saliva are present in the literature and little guidance is available on the standardization of type of saliva for use in in vitro protocols for erosive studies. The aim of this study was to evaluate the remineralizing capacity of different formulations of artificial saliva on initial enamel erosive lesion. METHODS: Bovine enamel blocks were subjected to short-term acidic exposure by immersion in citric acid 0.05 M (pH 2.5) for 15s, resulting in surface softening without tissue loss. Then 90 selected eroded enamel blocks were randomly and equally divided into 6 groups according to saliva formulation (n=15): Saliva 1 (contain mucin); Saliva 2 (Saliva 1 without mucin); Saliva 3; Saliva 4; Saliva 5 (contain sodium carboxymethyl cellulose) and control (C) (deionized water). After demineralization enamel blocks were subjected to remineralization by immersion in the saliva's formulations for 2h. Enamel remineralization was measured by superficial hardness test (% superficial hardness change). The data were tested using ANOVA and Tukey's test (p<0.05). RESULTS: All the tested formulations of artificial saliva resulted in significantly higher enamel remineralization compared to control (p<0.001). Saliva 3 showed higher percentage of enamel remineralization than Saliva 5 (p<0.05). CONCLUSIONS: Besides the variety of artificial saliva for erosion in vitro protocols, all the formulations tested were able to partially remineralize initial erosive lesions.

In vitro remineralization of enamel subsurface lesions and assessment of dentine tubule occlusion from NaF dentifrices with and without calcium.

UNLABELLED: Currently, fluoride is the most effective preventive treatment for remineralization of incipient carious lesions and dentinal hypersensitivity due to wasting disorders. The products containing fluoride, calcium and phosphate are also claim to remineralize early, non-cavitated enamel demineralization. The aim of this study was to investigate and compare the efficacy of two such products, Tooth Mousse and Clinpro tooth crème on remineralization and tubule occluding ability with 5000ppm fluoride-containing toothpaste. MATERIALS AND METHODS: Thirty third molar teeth were placed in demineralizing solution for 5 days such that only a window of 1mm x 5mm was exposed to the environment to produce artificial caries-like lesions and randomly assigned to three groups: Group I, 5000ppm sodium fluoride; Group II, GC MI paste plus and Group III, Clinpro tooth crème. Axial longitudinal sections of 140-160 µm of each tooth which included the artificial carious lesion taken and were photographed under polarized light microscope. The demineralized areas were then quantified with a computerized imaging system. The experimental materials were applied onto the tooth sections as a topical coating and subjected to pH-cycling for 28 days. To evaluate tubule occlusion ability, thirty dentin specimens of 2mm thickness were obtained from cervical third of sound third molars. Specimens were ultrasonicated and etched with 6% citric acid for 2 minutes to simulate the hypersensitive dentin. Specimens were randomly divided into above mentioned three groups (n=10). The test agents were brushed over the specimens with an electric toothbrush, prepared and observed under Scanning Electron Microscope for calculation of the percentage of occluded tubules. RESULTS: Group I showed a significantly greater percentage of remineralization than Group III and Group II. Comparison of the remineralization potential between group II and group III were not significant.In case of dentine hypersensitivity, Group I and group III showed greater percentage of tubule occlusion ability than Group II. Intergroup comparison of the tubule occlusion potential of group I and group III were not significant. INTERPRETATION AND CONCLUSION: Within the limitations of our study, sodium fluoride showed relatively greatest remineralizing and dentinal tubule occlusion property when compared with GC MI paste plus and Clinpro tooth crème.

3D assessment of void and gap formation in flowable resin composites using optical coherence tomography.

PURPOSE: To investigate the effect of composite type and cavity size on gap and void formation using optical coherence tomography (OCT). MATERIALS AND METHODS: Class I cavities of two depths (2 mm or 4 mm; 4 mm diameter) were prepared, treated with Tri-S Bond (Kuraray Medical), and bulk filled with either Surefil SDR Flow (SF; Dentsply) or Clearfil Majesty LV (MJ; Kuraray Medical) to form four groups. After 24 h, the specimens were 3D scanned using swept-source OCT (Santec) with 1310 nm laser at a 20 kHz sweep rate. In OCT tomograms, the bonding interface and the bulk of the restorations were evaluated. The percentage values of sealed interfaces (SP) and void volume (VP) for all groups were calculated and statistically analyzed using two- and one-way ANOVA and Tukey's post-hoc test. Selected specimens were cross sectioned and observed using a scanning electron microscope (SEM) and a confocal laser scanning microscope to confirm OCT findings. RESULTS: The following values were obtained for SP and VP, respectively: SF-2mm: 92% and 0.08%; SF-4mm: 66% and 0.13%; MJ-2mm: 86% and 1.79%; MJ-4mm: 33% and 1.96%. Both composites showed a significant increase in gap formation at 4-mm cavity depth (p < 0.001). While SF showed a rather homogeneous bulk compared to MJ, cavity depth did not significantly affect the void volume fraction (p = 0.08). CONCLUSION: The flowable composite with SDR (stress-decreasing resin) technology performed better than the conventional composite; however, bulk filling a 4-mm-deep cavity will compromise the sealing of the bonding interface regardless of the type of composite. OCT is a unique method of characterizing materials and their behaviors nondestructively and precisely.

Hypocalcified type of amelogenesis imperfecta in a large family: clinical, radiographic, and histological findings, associated dento-facial anomalies, and resulting treatment load.

OBJECTIVE: The purpose of this study was to report on the clinical, radiographic, and histological dental findings and the resulting treatment load in a five-generation family with amelogenesis imperfecta (AI). MATERIAL AND METHODS: Thirteen affected and 15 unaffected individuals were examined clinically and radiographically. In addition, four exfoliated deciduous teeth were examined by scanning electron microscopy and microradiography. RESULTS: The mode of inheritance of AI was autosomal-dominant. At eruption, most of the tooth enamel was yellow, lacking translucency, and prone to gradual loss in subjects with AI. Post-eruptive breakdown of enamel was extensive in accordance with the histological observations of hypomineralized and porous enamel. Extensive enamel loss and discoloration were observed in older affected individuals. The treatment need had been extensive: 76.2% of the total number of teeth present in affected individuals had been treated with partial or full coverage compared to 1.7% of the teeth in unaffected relatives. Unaffected individuals had more endodontically treated teeth than AI-affected relatives. Adjunctive findings, e.g. tooth agenesis, tooth impaction, pulp stones, enlarged follicular space, and taurodontism, were rare in both groups. CONCLUSIONS: Affected family members had the hypocalcified type of AI, which is characterized by severe hypomineralization, extensive post-eruptive loss, and discoloration of the enamel. Adjunctive findings were rare. Individuals with the hypocalcified type of AI have an extensive restorative treatment load compared to unaffected relatives.

An in vitro comparative assessment of different enamel contaminants during bracket bonding.

In orthodontics, adhesive failures can occur because of saliva contamination during bonding. However, most in vitro studies concerning bond strength of saliva-contaminated enamel disregard the influence of temperature changes in a wet environment. The aim of the present study was to compare the influence of saliva, blood and etching gel remnant contamination on shear bond strength (SBS) after thermocycling. After etching of extracted human third molars (n = 80), a conventional primer (Transbond XT) and a moisture-insensitive primer (Transbond MIP) were evaluated using the adhesive, Transbond XT, under dry conditions and after contamination with saliva, blood and etching gel remnants. To simulate temperature changes and the moisture of saliva in the oral cavity, all samples were thermocycled (6,000 x 5 degrees C/55 degrees C) in a mastication device before SBS testing. A Mann-Whitney U test was used to determine statistical differences. Under dry conditions Transbond XT and Transbond MIP showed no significant difference in SBS. However, clinically unacceptable (P = 0.005) bond strength was observed using Transbond XT after saliva and blood contamination. In wet conditions only Transbond MIP showed sufficient bond strength. If contamination during bonding is expected, a hydrophilic primer should be used. Under dry conditions hydrophilic or hydrophobic primers could be applied. Blood contamination seems to be a more serious problem for bond strength than saliva or etching gel contamination.

Assessment of enamel erosion and protective effect of salivary pellicle by surface roughness analysis and scanning electron microscopy.

PURPOSE: To assess dental erosion caused by 0.1% and 1.0% citric acid in vitro and to estimate the protective influence of experimentally formed salivary pellicle. MATERIALS AND METHODS: Bovine enamel slabs (n = 80) were polished and embedded in epoxy resin. For the formation of pellicle layer 40 specimens were immersed for 24 h in pooled human saliva. Erosion was caused by immersion in citric acid solution for 1, 5, 10 and 30 min. Erosive alterations on the pellicle-covered and non-covered enamel specimens were scored as a change (delta) of surface roughness parameters Ra, Rt and RzDIN using contact profilometer and observed in scanning electron microscope. RESULTS: Profilometric analysis of eroded enamel specimens emphasized the aggressiveness of even low concentrated citric acid with a short period of challenge. The change of roughness parameters after 1-min immersion in 0.1% citric acid were 16.4, 182.6 and 132.2 nm for deltaRa, deltaRt and deltaRzDIN, respectively, and 54.8, 516.6 and 258.2 nm after 1-min immersion in 1.0% citric acid. Changes of the surface roughness were dependent on the exposure time and concentration of acidic solution. Pellicle layer significantly reduced the extent of erosive destruction, which was additionally documented on SEM-micrographs. Residual pellicle-like structures were detected after 5 min of immersion in 0.1% citric acid. However, there were no significant differences in pellicle-covered and non-covered enamel slabs measured profilometrically for 1.0% citric acid with 10 min and 30 min exposure time. CONCLUSION: The findings confirm the property of pellicle layer to resist against erosive influence of organic acids, which is, however, limited by duration of acidic treatment and concentration of erosive agent.