Normal Enamel Research Articles

Surface Nanohardness of Normal and Fluorosed Enamel Adjacent to Restorative Materials: An In Vitro Study and Polarized Light Microscopy Analysis

To evaluate nanohardness of normal and fluorosed enamel in teeth restored with Cention N (CN), Equia forte (EF), glass ionomer cement (GIC), and resin composite using the nanoindentation test. Eighty freshly extracted human premolars were selected. Standardized cavities were prepared on the buccal surface of normal (40) and fluorosed (40) teeth. Based on the type of the restorative material, the teeth were subgrouped into (n = 10): CN, EF, Type VIII GIC, and Tetric N-Ceram (TNC). The teeth were subjected to pH cycle (progressive caries test), which consisted of alternative demineralization (18 hours) and remineralization with artificial saliva (6 hours) for 3 consecutive days. Surface nanohardness was determined using a nanoindenter at distances of 100, 200, and 300 μm from the restoration-tooth margin. A polarized light Microscope was used to correlate the effect of remineralization on the enamel. Data were analyzed by one-way ANOVA with the Scheffe's post hoc and independent t-test. Nanohardness values of the fluorosed/normal enamel adjacent to various materials in descending order were as follows: EF 3.67/2.95 GPa, GIC 3.33/3.15 GPa, CN 3.13/3.23 GPa, and TNC 1.17/1.82 GPa, respectively. Statistically significant differences were found among various materials in both types of the enamel (p < 0.05). Based on the nanohardness test, EF can be a better choice for restoration in fluorosed teeth, followed by CN and GIC; GIC was better in normal enamel; however, this was not significant compared to CN and EF. Tetric N-Ceram composite resin had least influence on increasing the nanohardness of the adjacent enamel. The surface nanohardness of normal and fluorosed enamel can be influenced by the type of restorative material used. The results of present study deserve clinician's attention while selecting restorative materials especially in dental fluorosis.

Comparison of the chemical composition and the structural characteristics of normal enamel from the teeth affected with early childhood caries in pre-term and full-term born children: An In vitro study

Background: Early childhood caries (ECC) is considered as one of the most concerned topics of investigation in order to prevent its occurrence by targeting multiple causative factors. Time of birth of a child has an effect on the development of tooth and might show differences in the structure and composition of enamel. Aim: To evaluate the chemical composition and structural characteristics of enamel in primary teeth of pre-and full-term born children affected with ECC. Material and Methods: Twenty extracted primary teeth from pre-term (n = 10) and full-term (n = 10) born children affected with ECC were selected. Unaffected portions of enamel were subjected to polarized light microscope (POLMI), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). Results: The thickness of prenatally formed enamel was less in pre-term born children under POLMI. The concentrations of calcium and phosphorus were higher in full-term born children on EDS analysis. The surfaces of enamel in primary teeth from full-term group were smooth whereas pitted and eroded along with a larger distribution of hypoplasia in pre-term group when observed under SEM. Conclusion: Primary teeth enamel of pre-term born children was found to be defective in both qualitative and quantitative aspects and could be a possible risk factor in the causation of ECC.

FAM20A is essential for amelogenesis, but is dispensable for dentinogenesis.

Mutations in the gene encoding family with sequence similarity 20, member A (FAM20A) caused amelogenesis imperfecta (AI), in humans. However, the roles of FAM20A in amelogenesis and dentinogenesis are poorly understood. In this study, we generated a Fam20a knockout (Sox2-Cre;Fam20afl/fl) mouse model by crossing Fam20afl/fl mice with Sox2-Cre transgenic mice, in which Fam20a was ablated in both dental epithelium and dental mesenchyme. We found that these mice developed an enamel phenotype that resembles human AI associated with FAM20A mutations, but did not have apparent dentin defects. The secretory stage ameloblasts in the mandibular incisors from the Sox2-Cre;Fam20afl/fl mice were shorter and detached from the enamel matrix, and subsequently lost their polarity, became disorganized and formed numerous spherical extracellular matrices in place of normal enamel. At the molecular level, the Sox2-Cre;Fam20afl/fl mice displayed dramatically reduced expression levels of the genes encoding the enamel matrix proteins, but unaltered levels of the genes encoding the dentin matrix proteins. Moreover, Fam20a ablation resulted in a great decrease in FAM20C protein level, but it did not alter the intracellular localization of FAM20C protein in ameloblasts and odontoblasts. These results indicate that FAM20A is essential for amelogenesis, but is dispensable for dentinogenesis.

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Guest Editorial

Evaluation of Remineralizing Efficacy of Calcium Sucrose Phosphate: A Systematic Review of In Vitro Studies

Background: Despite improved oral hygiene regime and availability of preventive formulations, dental caries continues to be a global dental problem. Calcium sucrose phosphate (CaSP) is a remineralizing agent with cariostatic action, which is commonly available in the form of tooth cream. Considering the paucity of evidence, this systematic literature review aims to evaluate the remineralizing efficacy of CaSP. Methodology: The review was conducted as per Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Various databases, including PubMed, Cochrane Central, and Google Scholar, were searched until March 15, 2018 and were assessed for inclusion by two independent reviewers. The primary outcome was to assess the remineralizing efficacy of CaSP, and the secondary outcome was to assess the potential of CaSP in arresting white spot lesion(s) on enamel. Results: Out of 2,876 articles, only 13 were qualified for inclusion. Included studies presented a low risk of bias for the following items: caries-free teeth or restoration, and adherence to manufacture’s instruction for the usage of remineralizing agent in the risk of bias scale. Ten studies reported an increase in the microhardness of enamel after CaSP application, and three studies reported the effect of CaSP on arresting white spot lesion(s). CaSP was found to be a better remineralizing agent in comparison to casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) and other remineralizing agents in terms of increasing microhardness of enamel. In addition, CaSP application was also found to have a beneficial effect in restoring the color of white spot lesion(s) to that of normal enamel. Conclusion: CaSP tooth cream was found to be an effective remineralizing agent, compared to others, such as CPP-ACP and CPP-ACPF, in terms of increasing the mean microhardness of enamel and arresting white spot lesion(s).

A Novel AMELX Mutation, Its Phenotypic Features, and Skewed X Inactivation

Amelogenesis imperfecta (AI) is a group of genetic disorders of defective dental enamel. Mutation of AMELX encoding amelogenin on the X chromosome is a major cause of AI. Here we report a Chinese family with hypoplastic and hypomineralized AI. Whole exome analysis revealed a novel mutation c.185delC in exon 5 of AMELX causing the frame shift p.Pro62ArgfsTer47 (or p.Pro62Argfs*47). By sequencing of polymerase chain reaction products and T-vector clones, the mutation was confirmed as homozygous in the proband, hemizygous in her father, and heterozygous in her mother. The proband and her father had small and yellowish teeth with thin and rough enamel that was radiographically indistinguishable from the underlying dentin. Scanning electronic microscopy of 1 maternal tooth showed cracks and exposed loosely packed enamel prisms in affected areas. Consistent with a 25:75 skewing of X inactivation in the peripheral blood DNA as measured by androgen receptor allele methylation, the surface of the mother’s tooth had alternating vertical ridges of transparent normal and white chalky enamel in a 34:66 ratio. In summary, this study provides one of the few phenotypic comparisons of hemizygous and homozygous AMELX mutations and suggests that the skewing of X inactivation in AI contributes to the phenotypic variations in heterozygous carriers of X-linked AI.

Prevalence of dental erosion in Pakistani children: A cross-sectional study

Introduction: Dental erosion has remained a topic of interest for more than a decade and now gripping greater attention with the rise in the number of cases being reported in children and young adults. Prevalence of dental erosion varies in different countries according to their different geographical locations, dietary habits and life styles of their people. However, little is known about the prevalence of tooth erosion in Pakistani children particular regarding the associated risk factors. Aims: This study was designed to explore the prevalence of dental erosion and to determine the associated predictors of dental erosion in school children of Pakistan aged 12 to 14 years.&#x0D; Methodology: A comparative cross-sectional Analytical study was conducted at a private school of Karachi, Pakistan from April 2016 till March 2017. The subjects were selected on the basis of non-probability convenient sampling. Children aged 12-14 years were included for this study and children having frequent hospitalizations were excluded. The two previously calibrated examiners participated in the clinical examinations and visited the selected schools. The clinical examinations were performed in well-lit classrooms or in shaded places under natural light using plane mouth mirrors and sterilized cotton to remove debris. The central incisors, lateral incisors, and first molars in the upper and lower jaws were examined.&#x0D; Results: School children were assessed by O’sullivan index which showed dental erosion of 42.8% on labial or buccal surface, 9.7% on lingual or palatal surface, 7.4% on occlusal or incisal, 4% on labial, incisal/occlusal and 7% on lingual, incisal/occlusal. Grade of severity of dental erosion showed normal enamel in 43.1%, matt appearance of enamel surface with no loss of contour in 20.1%, loss of enamel only in 35.8% and loss of enamel with exposure of dentine in 1%.&#x0D; Conclusion: The study concludes that dental erosion is a multifactor in origin and with time is becoming increasingly commonly in younger age group. It is important that as health providers we need to identify the possible risk factors and make the community aware of the ways to prevent this condition.&#x0D; Key words: Surfaces of teeth, enamel surface, Soft drinks and straw.

The Enamel Phenotype in Homozygous Fam83h Truncation Mice.

BackgroundTruncation FAM83H mutations cause human autosomal dominant hypocalcified amelogenesis imperfecta (ADHCAI), an inherited disorder characterized by severe hardness defects in dental enamel. No enamel defects were observed in Fam83h null mice suggesting that Fam83h truncation mice would better replicate human mutations.MethodsWe generated and characterized a mouse model (Fam83h Tr/Tr) expressing a truncated FAM83H protein (amino acids 1–296), which recapitulated the ADHCAI‐causing human FAM83H p.Tyr297* mutation.ResultsDay 14 and 7‐week Fam83h Tr/Tr molars exhibited rough enamel surfaces and slender cusps resulting from hypoplastic enamel defects. The lateral third of the Fam83h Tr/Tr incisor enamel layer was thinner, with surface roughness and altered enamel rod orientation, suggesting disturbed enamel matrix secretion. Regular electron density in mandibular incisor enamel indicated normal enamel maturation. Only mildly increased posteruption attrition of Fam83h Tr/Tr molar enamel was observed at 7‐weeks. Histologically, the Fam83h Tr/Tr enamel organ, including ameloblasts, and enamel matrices at sequential stages of amelogenesis exhibited comparable morphology without overt abnormalities, except irregular and less evident ameloblast Tomes' processes in specific areas.ConclusionsConsidering Fam83h−/− mice showed no enamel phenotype, while Fam83h Tr/Tr (p.Tyr297*) mice displayed obvious enamel malformations, we conclude that FAM83H truncation mutations causing ADHCAI in humans disturb amelogenesis through a neomorphic mechanism, rather than haploinsufficiency.

Genetic Deciphering of Early-Onset and Severe Retinal Dystrophy Associated with Sensorineural Hearing Loss.

The specific association of Leber congenital amaurosis (LCA) or early-onset severe retinal dystrophy (LCA-like) with sensorineural hearing loss (SHL) is uncommon. Recently, we ascribed some of these distinctive associations to dominant and de novo mutations in the β-tubulin 4B isotype-encoding gene (TUBB4B), providing a link between a sensorineural disease and anomalies in microtubules behavior. Here, we report 12 sporadic cases with LCA/SHL or LCA-like/SHL and no TUBB4B mutation. Trio-based whole exome sequencing (WES) identified disease-causing mutations in 5/12 cases. Four out of five carried biallelic mutations in PEX1 (1/4) or PEX6 (3/4), involved in peroxisome biogenesis disorders from Zellweger syndrome characterized by severe neurologic and neurosensory dysfunctions, craniofacial abnormalities, and liver dysfunction to Heimler syndrome associating SHL, enamel hypoplasia of the secondary dentition, nail abnormalities, and occasional retinal disease. Upon reexamination, the index case carrying PEX1 mutations, a 4-year-old girl, presented additional symptoms consistent with Zellweger syndrome. Reexamination of individuals with PEX6 mutations (1/3 unavailable) revealed normal nails but enamel hypoplasia affecting one primary teeth in a 4-year-old girl and severe enamel hypoplasia of primary teeth hidden by dental prosthesis in a 50-year-old male, describing a novel PEX6-associated disease of the Zellweger/Heimler spectrum. Finally, hemizygosity for a CACNA1F mutation was identified in an 18-year-old male addressed for LCA/SHL, redirecting the retinal diagnosis to congenital stationary night blindness (CSNB2A). Consistent with the pure CSNB2A retinal involvement, SHL was ascribed to biallelic mutations in another gene, STRC, involved in nonprogressive DFNB16 deafness.

In vitro assessment of erosive effects of some common soft drinks on dental hard tissues

Background/Aim: The chemical nature of soft drinks is acidic, so they possess the capacity to cause hard tissue erosion. The aim of this study is to assess the potentially erosive effect linked to pH and titratable acidity of some common soft drinks on dental hard tissues in prolonged time exposure. Material and Methods: Seven types of soft drinks in Romanian market were selected for this study. The pH and Titratable acidity were determined. Twenty one human dental hard tissue specimens were immersed in 5 ml solution each for 336h. Every 48h weight loss was determined for each specimen and after 336h volume changes were calculated. Enamel microhardness was determined using a Microhardness Tester model HV-1000 and compared to normal enamel microhardness. Results: The pH values of beverages ranged from 2.37 to 3.1, showing no significant differences. All specimens presented color and surface texture modifications, weight loss and volume reduction. There were found significant differences between the mean values of weight loss and enamel microhardness of each type of specimens and type of beverages tested. The most representative findings were achieved by indentations done in specific zones on Sprite® immersed specimen. This result suggest that microhardness near the eroded surface was significant lower than in other zones. Conclusions: Data obtained have shown that all the soft drinks tested had an erosive effect, causing dental hard tissue dissolution. For prolonged time exposure titratable acidity may be a major predictor for erosive potential. Dental erosion may affect different levels of enamel causing decreased enamel microhardness.

Team Approach for the Management of Amelogenesis Imperfecta

Amelogenesis imperfecta is a developmental disturbance that interferes with normal enamel formation in the absence of a systemic disorder. This case report describes a multidisciplinary team approach for the oral rehabilitation of a young adult patient diagnosed with hypocalcified amelogenesis imperfecta with anterior single tooth crossbite. The specific objectives of this treatment were to enhance esthetics, eliminate tooth sensitivity and restore masticatory function. Treatment included maintenance of gingival health, correction of crossbite, surgical crown lengthening of the maxillary and mandibular posterior teeth and placement of full mouth metal-ceramic crowns. The patient was highly satisfied with the aesthetic and functional outcome of the treatment.

Effectiveness of the Multilayered Caries Model and Visuo-tactile Virtual Reality Simulator for Minimally Invasive Caries Removal: A Randomized Controlled Trial.

This work presents the multilayered caries model with a visuo-tactile virtual reality simulator and a randomized controlled trial protocol to determine the effectiveness of the simulator in training for minimally invasive caries removal. A three-dimensional, multilayered caries model was reconstructed from 10 micro-computed tomography (CT) images of deeply carious extracted human teeth before and after caries removal. The full grey scale 0-255 yielded a median grey scale value of 0-9, 10-18, 19-25, 26-52, and 53-80 regarding dental pulp, infected carious dentin, affected carious dentin, normal dentin, and normal enamel, respectively. The simulator was connected to two haptic devices for a handpiece and mouth mirror. The visuo-tactile feedback during the operation varied depending on the grey scale. Sixth-year dental students underwent a pretraining assessment of caries removal on extracted teeth. The students were then randomly assigned to train on either the simulator (n=16) or conventional extracted teeth (n=16) for 3 days, after which the assessment was repeated. The posttraining performance of caries removal improved compared with pretraining in both groups (Wilcoxon, p<0.05). The equivalence test for proportional differences (two 1-sided t-tests) with a 0.2 margin confirmed that the participants in both groups had identical posttraining performance scores (95% CI=0.92, 1; p=0.00). In conclusion, training on the micro-CT multilayered caries model with the visuo-tactile virtual reality simulator and conventional extracted tooth had equivalent effects on improving performance of minimally invasive caries removal.

Adhesion to enamel of teeth affected by molar incisor hypomineralization: Literature review

Background/Aim: Molar incisor hypomineralization (MIH) is a qualitative defect of systemic origin, affecting permanent first molars and often permanent incisors. The treatment modalities can include, amongst others, fissure sealants for prevention of dental caries and composite restorations. Both require adhesion to tooth structure. The aim of this study was to review the literature on the adhesion to enamel affected by MIH. Material and Methods: A search of PupMed/Medline, Research Gate and Google Scholar was performed and limited between 2003, when the judgement criteria for MIH were set, and 2016. Thirty-three papers were considered relevant to the subject including five in vivo and six in vitro studies. Studies involving less than ten teeth were excluded. Results: A fouryear clinical trial showed that the application of a total-etch 2-step adhesive system prior to sealant placement is superior to the etch-seal technique. Despite the high success rate of composite restorations shown in three clinical longitudinal studies, there are conflicting results over self-etch being superior to total etch adhesive systems. Pretreating the enamel surface, prior to the adhesive system, with fluoride preventive solutions could reduce the mikroleakage under orthodontic brackets. Three in vitro studies provide inconsistent data about NaOCl pretreating potentials to improve adhesion of composite restorations. Resin infiltration, prior to resin restorations, could improve the microhardness of defected enamel, which may lead to increased bond strength, especially in combination with NaOCl pretreatment. Conclusions: Adhesion to enamel affected by molar incisor hypomeralization is inferior compared to normal enamel. Sealants applied with the etch-bondseal technique have greater retention than with the etch-seal technique. Further research is required to provide evidence of the effectiveness of the adhesive system and pretreatment to achieve optimal bonding to MIH.

The Etching Effect of Co2 Laser on The Shear Bond Strength of Bleached Teeth

Background: Tooth discoloration is one of the great esthetic problems in dentistry, Despite vital bleaching, is often considered a first step to improve the appearance of teeth, reports are controversial about the effect of bleaching on the shear bond strengths (SBS) of brackets. Etching of enamel surface can be carried out by acid or laser, there was controversial about the efficiency of CO2 laser as enamel surface etchant Objective: The aim of the present study is to detect if there is a significant reduction in SBS of bleached teeth, and to detect the effect of CO2 laser as etchant on both bleached and normal teeth. Methods and materials: Forty non-carious first premolars are divided into 2 main groups: None- bleached (A) and Bleached (B) groups, of 20 specimens for each group, then the groups were subdivided into 2 subgroups (10 specimens for each subgroup). Group (B) teeth were bleached with chemically activated 40% hydrogen peroxide, while group (A) teeth were left without bleach- ing. The subgroups teeth (A1 and B1) were etched with CO2 laser and the subgroups (A2 and B2) were etched with 37% phosphoric acid. After bracket bonding, samples were then thermally cycled for 500 cycles between( 5°C and 55°C). Debonding was performed with a shearing force using the universal testing machine, then ANOVA and LSD test were used to specify if there was a significant difference between groups. Results: there was the nonsignificant difference in mean SBS of both phosphoric acid etching and CO2 laser etching in both bleached and normal surface enamel specimens A and B groups. Whereas there was a significant difference in mean shear bond strength between the CO2 laser etched and the phosphoric acid etched groups with highest mean values in the phosphoric acid etched subgroups, Conclusion: The results of this in vitro study suggest that hydrogen peroxide bleaching does not affect the shear bond strength of metal orthodontic brackets when bonding occurred 1 week after bleaching and CO2 laser etching has low shear bond strength values making it not suitable for clinical use.

Amelogenesis imperfecta caused by N-terminal enamelin point mutations in mice and men is driven by endoplasmic reticulum stress.

‘Amelogenesis imperfecta’ (AI) describes a group of inherited diseases of dental enamel that have major clinical impact. Here, we identify the aetiology driving AI in mice carrying a p.S55I mutation in enamelin; one of the most commonly mutated proteins underlying AI in humans. Our data indicate that the mutation inhibits the ameloblast secretory pathway leading to ER stress and an activated unfolded protein response (UPR). Initially, with the support of the UPR acting in pro-survival mode, Enamp.S55I heterozygous mice secreted structurally normal enamel. However, enamel secreted thereafter was structurally abnormal; presumably due to the UPR modulating ameloblast behaviour and function in an attempt to relieve ER stress. Homozygous mutant mice failed to produce enamel. We also identified a novel heterozygous ENAMp.L31R mutation causing AI in humans. We hypothesize that ER stress is the aetiological factor in this case of human AI as it shared the characteristic phenotype described above for the Enamp.S55I mouse. We previously demonstrated that AI in mice carrying the Amelxp.Y64H mutation is a proteinopathy. The current data indicate that AI in Enamp.S55I mice is also a proteinopathy, and based on comparative phenotypic analysis, we suggest that human AI resulting from the ENAMp.L31R mutation is another proteinopathic disease. Identifying a common aetiology for AI resulting from mutations in two different genes opens the way for developing pharmaceutical interventions designed to relieve ER stress or modulate the UPR during enamel development to ameliorate the clinical phenotype.

Effects of two adhesion boosters on depth of penetration of orthodontic adhesive on fluorosed and normal enamel: A confocal microscopic study

Effects of two adhesion boosters on depth of penetration of orthodontic adhesive on fluorosed and normal enamel: A confocal microscopic study

Effects of various debonding and adhesive clearance methods on enamel surface: an in vitro study

BackgroundThe purpose of this study was to evaluate orthodontic debonding methods by comparing the surface roughness and enamel morphology of teeth after applying two different debonding methods and three different polishing techniques.MethodsForty eight human maxillary premolars, extracted for orthodontic reasons, were randomly divided into three groups. Brackets were bonded to teeth with RMGIC (Fuji Ortho LC, GC, Tokyo, Japan) (two groups, n = 18 each) after acid etching (30s), light cured for 40 s, exposed to thermocycling, then underwent 2 different bracket debonding methods: debonding pliers (Shinye, Hangzhou, China) or enamel chisel (Jinzhong, Shanghai, China); the third group (n = 12) comprised of untreated controls, with normal enamel surface roughness. In each debonded group, three cleanup techniques (n = 6 each) were tested, including (I) diamond bur (TC11EF, MANI, Tochigi, Japan) and One-Gloss (Midi, Shofu, Kyoto, Japan), (II) a Super-Snap disk (Shofu, Kyoto, Japan), and (III) One-Gloss polisher. The debonding methods were compared using the modified adhesive remnant index (ARI, 1–5). Cleanup efficiencies were assessed by recording operating times. Enamel surfaces were qualitatively and quantitatively evaluated with scanning electron microscopy (SEM) and surface roughness tester, respectively. Two surface roughness variables were evaluated: Ra (average roughness) and Rz (10-point height of irregularities).ResultsThe ARI scores of debonded teeth were similar with debonding pliers and enamel chisel (Chi-square = 2.19, P > 0.05). There were significant differences between mean operating time in each group (F = 52.615, P < 0.01). The diamond bur + One-Gloss took the shortest operating time (37.92 ± 3.82 s), followed by the Super-Snap disk (56.67 ± 7.52 s), and the One-Gloss polisher (63.50 ± 6.99 s). SEM appearance provided by the One-Gloss polisher was the closest to the intact enamel surface, and surface roughness (Ra: 0.082 ± 0.046 μm; Rz: 0.499 ± 0.200 μm) was closest to the original enamel (Ra: 0.073 ± 0.048 μm; Rz: 0.438 ± 0.213 μm); the next best was the Super-Snap disk (Ra: 0.141 ± 0.073 μm; Rz: 1.156 ± 0.755 μm); then, the diamond bur + One-Gloss (Ra: 0.443 ± 0.172 μm; Rz: 2.202 ± 0.791 μm).ConclusionsDebonding pliers were safer than enamel chisels for removing brackets. Cleanup with One-Gloss polisher provided enamel surfaces closest to the intact enamel, but took more time, and Super-Snap disks provided acceptable enamel surfaces and efficiencies. The diamond bur was not suitable for removing adhesive remnant.

Impact of welding the dental enamel walls of the fissure system using semiconductor laser: In-Vitro study

Background: Dental caries is as yet considered the commonest disease of childhood and adolescence with high incidence in some individuals. A basic and noninvasive caries preventive regimen as treating tooth enamel with a laser, either alone or in combination have been proved its effectiveness to reduce enamel solubility and caries incidence rates. Methods: Forty specimens were divided into 4 groups, each group contained 10 teeth; group1 (control group) normal enamel; group 2: immersed in artificial caries media; group 3: subjected to diode laser irradiation; group 4: subjected to diode laser irradiation and artificial caries media. Specimens were examined with environmental scanning electron microscope and microhardness measurement. Results: The environmental scanning electron microscope examination of group 3 revealed partial closure of the occlusal depressions (pits and fissures), and furthermore great resistance to caries occurrence was accomplished in group 4. A high significant difference was recognized in group 3 while group 4 showed non-significant reduction in its hardness.

A rare co-occurrence of facial talon's cusp on fused maxillary permanent central and lateral incisor

Fusion is a developmental anomaly of dental hard tissues characterised by the union of two adjacent teeth. It can be complete or incomplete and commonly seen in deciduous than in the permanent dentition with higher frequency in anterior maxillary regions. Talon’s cusp is an unusual cuspal projection from the lingual aspect of the tooth with normal enamel and dentin and varying degree of pulp tissue. It commonly affects the permanent maxillary lateral incisors followed by central incisors and canines. Talon cusp is mostly found on the lingual aspect of teeth and rarely it projects from the facial aspect. We hereby report a case of fusion of permanent left central and lateral incisor with facial talon cusp which is rarely reported.

Effects of two adhesion boosters on depth of penetration of orthodontic adhesive on fluorosed and normal enamel: A confocal microscopic study

Objectives: This study has been conducted to unveil adhesion promoter's underlying microscopic mechanism using confocal microscope. Materials and Methods: Fifty maxillary first premolars (25 fluorosed and 25 nonfluorosed) were selected. The teeth were divided into 4 groups of 10 teeth each based on the adhesion booster applied and two control groups of 5 fluorosed and 5 nonfluorosed teeth without adhesion booster. Two different adhesion boosters, All-Bond 3 (Bisco, Schaumburg, IL, USA) and Enhance LC (Reliance, Itasca, IL, USA), were mixed with Rhodamine B fluorescent dye and applied on the tooth to facilitate the detection of resin tags in the confocal microscope. The teeth were sliced to a cross-section of 800 μm by hard tissue microtome. Each cross section was scanned in confocal microscope till three distinct resin tags were seen, and this image was stored and quantified. The depth of penetration of adhesive resin tag was chosen as a measure of micromechanical bonding. Data obtained were statistically analyzed. Results: The maximum depth of penetration was recorded in fluorosed/All-Bond 3 group of 75.57 μm and a minimum depth of penetration was in fluorosed and conventional primer group of 26.46 μm. Conclusions: This shows that micromechanical bonding is compromised in fluorosed teeth. Both the adhesion boosters, All-Bond 3 and Enhance LC, enhanced the depth of resin penetration in fluorosed as well as nonfluorosed teeth while conventional primer did not prove to be very useful. Thus, adhesion boosters have been beneficial to increase the micromechanical bonding in cases where bonding is compromised, thus providing a good solution to effective orthodontic bonding.