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Enamel
Kinds of Enamel Terms modified by Enamel Selected AbstractsONE-YEAR TENSILE BOND STRENGTHS OF TWO SELF-ETCHING PRIMERS TO BOVINE ENAMELJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 4 2004John M. Powers PhD [source] DEFINITIVE DIAGNOSIS OF EARLY ENAMEL AND DENTINAL CRACKS BASED ON MICROSCOPIC EVALUATIONJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 7 2003Joel H. Berg DDS [source] OXYGEN AND CARBON ISOTOPE ANALYSIS OF HUMAN TOOTH ENAMEL FROM THE NEW KINGDOM SITE OF TOMBOS IN NUBIAARCHAEOMETRY, Issue 5 2010M. R. BUZON This study examines the feasibility of using oxygen isotope analysis of tooth carbonate to identify immigrants from the New Kingdom site of Tombos in Nubia (n = 30). In comparison with published data, the results (,18Oca,VSMOW = 31.4,) imply a substantial presence of immigrants. However, further analysis of these data strongly suggests the need to consider hydrological and cultural factors such as the contribution of aquifer waters to the Nile, use of groundwater sources, and differences in handling and storage of water. The carbon isotope analysis, in conjunction with published 87Sr/86Sr data, provides additional support for the presence of immigrants at Tombos. [source] IDENTIFICATION AND DIFFERENTIATION OF OPAQUE CHINESE OVERGLAZE YELLOW ENAMELS BY RAMAN SPECTROSCOPY AND SUPPORTING TECHNIQUES*ARCHAEOMETRY, Issue 1 2010J. MIAO Using Raman spectroscopy, energy-dispersive X-ray fluorescence and X-ray diffraction, the Pb,Sn,Sb triple oxide yellow and lead,tin yellow have been identified on two pieces of cloisonné enamel (Falangcai) porcelains. Lead,tin yellow and lead antimonate yellow have been identified on famille rose porcelains manufactured before and after 1911, respectively. The replacement of the Pb,Sn,Sb triple oxide yellow by lead,tin yellow and that of the lead,tin yellow by lead antimonate yellow are discussed. [source] THE BLUE ENAMELS IN THE BAROQUE DECORATIONS OF THE CHURCHES OF PALERMO, SICILY: FE2+ -COLOURED GLASSES FROM LIME KILNS*ARCHAEOMETRY, Issue 2 2009G. ARTIOLI Deep blue glasses coloured by octahedral Fe2+ cations are often reported as textbook examples of blue pigmentation. However, despite the possibility of laboratory synthesis under reducing conditions, to date there are no well-reported occurrences of their production and use in the past. A thorough historical, ethnographic, mineralogical, and chemico-physical investigation of the ,smaltini di calcara' from several baroque churches in Palermo, Sicily, has revealed that the blue enamels widely used for altar decorations in the 17th and 18th centuries are actually a unique case of ancient blue glasses pigmented by divalent iron cations in distorted octahedral coordination. This mixed-alkali glass was accidentally produced under severely reducing conditions in the local kilns during production of lime. [source] Role of preliminary etching for one-step self-etch adhesivesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2010Michael Taschner Taschner M, Nato F, Mazzoni A, Frankenberger R, Krämer N, Di Lenarda R, Petschelt A, Breschi L. Role of preliminary etching for one-step self-etch adhesives. Eur J Oral Sci 2010; 118: 517,524. © 2010 Eur J Oral Sci The aim of this study was to analyse the effect of preliminary phosphoric acid etching of enamel and dentine before the application of two, one-step self-etch adhesive systems. The systems were applied onto acid-etched or smear-layer-covered enamel and dentine. The treatment groups were as follows: group 1, Adper Easy Bond (3M ESPE) on etched substrate; group 2, Adper Easy Bond (control); group 3, iBond Self-Etch (Heraeus Kulzer) on etched substrate; and group 4, iBond Self-Etch (control). Enamel and dentine bond strengths were calculated using microshear and microtensile bond-strength tests. Additional specimens were prepared to evaluate nanoleakage at the dentine,adhesive interface and were investigated using light microscopy or transmission electron microscopy. Both adhesives demonstrated higher microshear bond strengths when enamel was pre-acid-etched with phosphoric acid (Adper Easy Bond 28.7 ± 4.8 MPa; iBond Self-Etch 19.7 ± 3.6 MPa) compared with controls (Adper Easy Bond 19.2 ± 3.3 MPa; iBond Self-Etch 17.5 ± 2.7 MPa) and increased microtensile bond strength when applied on acid-etched (Adper Easy Bond 35.8 ± 5.7 MPa; iBond Self-Etch 24.3 ± 7.9 MPa) vs. smear-layer-covered dentine (Adper Easy Bond 26.9 ± 6.2 MPa; iBond Self-Etch 17.6 ± 4.3 MPa). Adper Easy Bond showed lower nanoleakage than iBond Self-Etch, irrespective of preliminary etching. The results of this study support the use of phosphoric acid etching before the application of one-step self-etch adhesive systems. [source] Dating methods for sediments of caves and rockshelters with examples from the Mediterranean RegionGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2001H. P. Schwarcz A wide range of potential dating methods may be applied to archaeological deposits found in caves and rockshelters, depending on the nature of the deposit and age range of the deposit. Organic sediments, including faunal and floral material, can be dated by radiocarbon (AMS and high-sensitivity beta-counting). Many karstic features contain speleothems which can be dated with high accuracy by U-series. Wind-blown detritus, where it is the dominant constituent of the cave deposits, can be dated by luminescence (TL, OSL, or IRSL), taking care to avoid material fallen into the deposits from the shelter/cave walls. Fireplaces contain burned rocks (including stone artifacts) which can be dated by TL. Enamel from the teeth of mammals is present in most sites, representing either animal residents of the shelter, or residues from food brought to the shelter by human residents. Electron spin resonance (ESR) dating of enamel is applicable over a wide time range, with high accuracy and reasonable precision where uranium accumulation in teeth is low, but with lower precision where uranium content in teeth is high. In general, multiple dating methods applied to a site may resolve ambiguities arising from uncertain model assumptions in some dating methods. © 2001 John Wiley & Sons, Inc. [source] Appositional enamel growth in molars of South African fossil hominidsJOURNAL OF ANATOMY, Issue 1 2006Rodrigo S. Lacruz Abstract Enamel is formed incrementally by the secretory activity of ameloblast cells. Variable stages of secretion result in the formation of structures known as cross striations along enamel prisms, for which experimental data demonstrate a correspondence with daily periods of secretion. Patterns of variation in this daily growth are important to understanding mechanisms of tooth formation and the development of enamel thickness. Transmitted light microscopy (TLM) of histological ground sections and scanning electron microscopy (SEM) of bulk specimens or their surface replicas are the usual methods for investigating cross striations. However, these methods pose some constraints on the study of these features in Plio-Pleistocene hominid enamel, the specimens of which may only rarely be sectioned for TLM or examined on only their most superficial surfaces for SEM. The recent development of portable confocal scanning optical microscopy (PCSOM) resolves some of the restrictions on fractured enamel surfaces, allowing the visualization of cross striations by direct examination. This technology has been applied here to the study of Australopithecus africanus and Paranthropus robustus hominid molars from the Plio-Pleistocene of South Africa. We hypothesize that these taxa have increased enamel appositional rates compared with modern humans, because despite having thicker enamelled molars (particularly P. robustus), the enamel crowns of these fossil taxa take an equivalent or reduced amount of time to form. Cross striations were measured in cuspal, lateral and cervical regions of the enamel crowns, and, within each region, the inner, middle and outer zones. Values obtained for A. africanus outer zones of the enamel crown are, in general, lower than those for P. robustus, indicating faster forming enamel in the latter, while both taxa show higher rates of enamel growth than modern humans and the African great apes. This demonstrates a relatively high degree of variability in the mechanisms underlying the development of enamel across taxa. [source] Bleaching Agents with Varying Concentrations of Carbamide and/or Hydrogen Peroxides: Effect on Dental Microhardness and RoughnessJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 6 2008JULIANA JENDIROBA FARAONI-ROMANO DDS ABSTRACT Purpose:, To evaluate the effect of low and highly concentrated bleaching agents on microhardness and surface roughness of bovine enamel and root dentin. Methods:, According to a randomized complete block design, 100 specimens of each substrate were assigned into five groups to be treated with bleaching agents containing carbamide peroxide (CP) at 10% (CP10); hydrogen peroxide (HP) at 7.5% (HP7.5) or 38% (HP38), or the combination of 18% of HP and 22% of CP (HP18/CP22), for 3 weeks. The control group was left untreated. Specimens were immersed in artificial saliva between bleaching treatments. Knoop surface microhardness (SMH) and average surface roughness (Ra) were measured at baseline and post-bleaching conditions. Results:, For enamel, there were differences between bleaching treatments for both SMH and Ra measurements (p = 0.4009 and p = 0.7650, respectively). SMH significantly increased (p < 0.0001), whereas Ra decreased (p = 0.0207) from baseline to post-bleaching condition. For root dentin, the group treated with CP10 exhibited the significantly highest SMH value differing from those groups bleached with HP18/CP22, HP7.5, which did not differ from each other. Application of HP38 resulted in intermediate SMH values. No significant differences were found for Ra (p = 0.5975). Comparing the baseline and post-bleaching conditions, a decrease was observed in SMH (p < 0.0001) and an increase in Ra (p = 0.0063). Conclusion:, Bleaching agents with varying concentrations of CP and/or HP are capable of causing mineral loss in root dentin. Enamel does not perform in such bleaching agent-dependent fashion when one considers either hardness or surface roughness evaluations. CLINICAL SIGNIFICANCE Bleaching did not alter the enamel microhardness and surface roughness, but in root dentin, microhardness seems to be dependent on the bleaching agent used. [source] Definitive Diagnosis of Early Enamel and Dentin Cracks Based on Microscopic EvaluationJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 7 2003DAVID J. CLARK DDS [source] Using carbon isotopes to track dietary change in modern, historical, and ancient primatesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Matt Sponheimer Abstract Stable isotope analysis can be used to document dietary changes within the lifetimes of individuals and may prove useful for investigating fallback food consumption in modern, historical, and ancient primates. Feces, hair, and enamel are all suitable materials for such analysis, and each has its own benefits and limitations. Feces provide highly resolved temporal dietary data, but are generally limited to providing dietary information about modern individuals and require labor-intensive sample collection and analysis. Hair provides less well-resolved data, but has the advantage that one or a few hair strands can provide evidence of dietary change over months or years. Hair is also available in museum collections, making it possible to investigate the diets of historical specimens. Enamel provides the poorest temporal resolution of these materials, but is often preserved for millions of years, allowing examination of dietary change in deep time. We briefly discuss the use of carbon isotope data as it pertains to recent thinking about fallback food consumption in ancient hominins and suggest that we may need to rethink the functional significance of the australopith masticatory package. Am J Phys Anthropol 140:661,670, 2009. © 2009 Wiley-Liss, Inc. [source] The unmet treatment need of traumatized anterior teeth in selected secondary school children in Ibadan, NigeriaDENTAL TRAUMATOLOGY, Issue 1 2010Mojirade Deborah Ajayi The aim of this study was to assess the prevalence of damage to permanent anterior teeth in school adolescents, the average duration of trauma and to ascertain the level of the unmet treatment need. A total of 1532 secondary school children between the ages 12 and 19 years participated in the study. They were randomly selected from public secondary schools in five local government areas in Ibadan using a multistage sampling method. Participants were examined with the aid of mouth mirrors and probes under natural light. Traumatic anterior dental injuries were recorded by the same investigator (DMA) according to WHO classification. One hundred and sixty-five participants sustained injuries to their anterior teeth. Their mean age was 15.47 ± 2.09 years, with a male to female ratio of 1.5:1. The commonest cause was fall (78.8%) with road traffic accident being the least (1.8%). The tooth most commonly injured is the upper left incisor (48.0%) closely followed by upper right central (43.1%). Enamel fracture was seen in 46.5% and enamel,dentine in 42.6% of the traumatized teeth. Most (79.4%) of the children sustained injury to one tooth only. Of the participants, only 30 (18.2%) had previous dental consultation while only nine (5.5%) consulted the dentist following the trauma; however, none of the teeth had any form of restoration. Average time elapsed between trauma and dental examination was about 3.5 years. Many participants had had injury for about 2 years before dental examination. In conclusion, there is a high unmet treatment need of traumatized anterior teeth in the study population. [source] Two-year follow-up of fractured anterior teeth restored with direct composite resin: report of three casesDENTAL TRAUMATOLOGY, Issue 5 2008Emre Ozel Fractures of maxillar central incisors including enamel and dentin were diagnosed. Beveling with diamond bur was performed in all four cases. Dentin was cleaned with tungsten carbid bur. The teeth were etched with 37% phosphoric acid, restored with an adhesive system and microhybrid composite. Finishing and polishing procedures were performed by discs (Sof-Lex) and burs. Restorations were found successful according to modified United States Public Health Service (USPHS) criteria after 2 years in terms of retention, color match, marginal discoloration, secondary caries, marginal adaptation, and surface texture. [source] Effect of crown fracture on the surrounding periodontiumDENTAL TRAUMATOLOGY, Issue 3 2008Janaína Cristina Gomes To reach the long axis of the tooth, an impact device was applied to eight teeth of four adult dogs to produce trauma. Crown fractures involving the enamel and dentin, with or without pulpar exposure and without dislocation, mobility or gingival bleeding were analyzed within the post-trauma periods of 30 min, 1, 3, and 7 days. The force of impact that resulted in coronary fracture, although dissipated at the time of fracture, reverberated in the surrounding periodontium and may generate not only light histological alterations with a rapid re-establishment of the tissues, but also an intense inflammatory condition required as long as 7 days to clear up. The gravity of these inflammatory reactions unleashed in these teeth's periapical tissues depends on the absorption of impact by the periodontal structures and the individual susceptibility of each organism. [source] Surgical extrusion of a crown-root fractured immature permanent incisor: 36 month follow-upDENTAL TRAUMATOLOGY, Issue 6 2007Zuhal K Abstract,,, Crown-root fracture is defined as a fracture involving enamel, dentin and pulp and can be classified as either complicated or uncomplicated. The tooth with crown-root fracture presents a lot of problems during coronal restorations and extraction was formerly used in many cases. But loss of a permanent incisor in a young patient may create severe emotional problems and alternative treatment approaches must be considered. This report presents the successful results of a surgical extrusion of a complicated crown-root fractured, immature permanent incisor in a 9-year-old boy. Examination 36 months after the trauma indicated that the treatment had provided functional and esthetic results. [source] Prevalence of crown fractures in 8,10 years old schoolchildren in Canoas, BrazilDENTAL TRAUMATOLOGY, Issue 5 2004Maximiano Ferreira Tovo Abstract,,, The objective of this work was to evaluate the prevalence of children with crown fractures in permanent anterior teeth in 206 schoolchildren (104 girls and 102 boys) between the ages of 8 and 10 years, enrolled in three public schools in the city of Canoas, Brazil. The prevalence found was 17% with no significant difference between boys and girls, as well as between the ages. The most affected tooth was the maxillary central incisor, and a majority of the children showed only one affected tooth (88.6%). The types of fracture most commonly found were oblique and horizontal, and the portions of dental structures most affected were ,enamel only' and ,enamel and dentin'. Only seven children (20%) sought out dental treatment. [source] Dental trauma in Turkish children, ,stanbulDENTAL TRAUMATOLOGY, Issue 2 2003Betul Kargul Abstract,,, Numerous studies focus on visits to dental clinics for emergent dental problems. Many are all-inclusive, studying traumatic injuries as well as visits for infection and other causes. Epidemiologic studies have focused on the investigation of the prevalence or incidence of dental injury. The patients were evaluated at Pediatric Dentistry, Marmara University Dental School, ,stanbul over a 2-year period. For these 300 patients (446 teeth), specific diagnoses were evaluated. Dental injuries that presented most frequently in permanent dentition were crown fractures of enamel only and crown fractures of enamel and dentin. The most frequently presented dental injury in primary dentition were avulsions and crown fractures of enamel. The more frequent treatments for primary teeth were examination only. Bandage restoration, space maintainer were common procedures for permanent teeth. [source] The prevalence of traumatic injuries treated in the pedodontic clinic of Ankara University, Turkey, during 18 monthsDENTAL TRAUMATOLOGY, Issue 6 2002Abstract , , ,The purpose of this study was to evaluate the type and prevalence of dental injuries referred to Ankara University, School of Dentistry, Department of Pedodontics, Turkey. One hundred and forty-seven patients with 234 traumatized teeth presented during 18-month interval. Of the 147 patients, 85 were boys and 62 were girls. The most frequent trauma occurred in the age of 11 years. The maxillary central incisors were found to be the most affected tooth in both primary and permanent dentition injuries. The maxillary arch is involved in a higher percentage of trauma cases (95.72%). The most common cause of injuries are falls (67.34%). In the primary dentition, the most common type of injury is extrusive luxation (38.23%) and in the permanent dentition, it is fracture of enamel,dentin without pulpal involvement (50.5%). From 147 patients, only 82 presented to our clinic within 1 h and 10 days after the injury time. It reveals that there is a need to inform the public of what they should do in cases of dental trauma, and how important it is to contact a dentist immediately. [source] Prevalence of dental trauma in 5,6- and 12,14-year-old boys in Riyadh, Saudi ArabiaDENTAL TRAUMATOLOGY, Issue 4 2001Ibrahim Al-Majed Abstract , This study involved 354 boys aged 5,6 years and 862 boys aged 12,14 years, attending 40 schools in Riyadh. All children were examined at school by a single dental examiner, using criteria similar to those employed in the survey of children's dental health in the United Kingdom. The prevalence of dental trauma in 354 Saudi boys aged 5,6 years was 33%. The most common type of dental trauma was fracture of enamel (71%) followed by loss of tooth due to trauma (13%), fracture into enamel and dentine (7%), discolouration (5%), pulp involvement (4%). No relationship between the degree of overjet and the occurrence of dental trauma in the primary dentition was observed. The prevalence of dental trauma in 862 12,14-year-old boys was 34%. The commonest dental trauma was fracture of enamel (74%) followed by fracture into enamel and dentine (15%), fracture into enamel-dentine and pulp (5%), loss of tooth due to trauma (3%), and discolouration (0.4%). A significant relationship (P=0.02) between the increased overjet (, 6 mm) and the occurrence of dental trauma in the permanent dentition was reported. The present study found no evidence of dental care provided for traumatised primary incisors in 5,6-year-old boys. The treatment of dental trauma in 12,14-year-old boys was negligible (2.4%). The present Saudi Arabian study showed higher prevalence of dental trauma in 5,6- and 12,14-year-old boys than the reported results of the United Kingdom Children's Dental Health Survey of the same age groups. [source] Role of preliminary etching for one-step self-etch adhesivesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2010Michael Taschner Taschner M, Nato F, Mazzoni A, Frankenberger R, Krämer N, Di Lenarda R, Petschelt A, Breschi L. Role of preliminary etching for one-step self-etch adhesives. Eur J Oral Sci 2010; 118: 517,524. © 2010 Eur J Oral Sci The aim of this study was to analyse the effect of preliminary phosphoric acid etching of enamel and dentine before the application of two, one-step self-etch adhesive systems. The systems were applied onto acid-etched or smear-layer-covered enamel and dentine. The treatment groups were as follows: group 1, Adper Easy Bond (3M ESPE) on etched substrate; group 2, Adper Easy Bond (control); group 3, iBond Self-Etch (Heraeus Kulzer) on etched substrate; and group 4, iBond Self-Etch (control). Enamel and dentine bond strengths were calculated using microshear and microtensile bond-strength tests. Additional specimens were prepared to evaluate nanoleakage at the dentine,adhesive interface and were investigated using light microscopy or transmission electron microscopy. Both adhesives demonstrated higher microshear bond strengths when enamel was pre-acid-etched with phosphoric acid (Adper Easy Bond 28.7 ± 4.8 MPa; iBond Self-Etch 19.7 ± 3.6 MPa) compared with controls (Adper Easy Bond 19.2 ± 3.3 MPa; iBond Self-Etch 17.5 ± 2.7 MPa) and increased microtensile bond strength when applied on acid-etched (Adper Easy Bond 35.8 ± 5.7 MPa; iBond Self-Etch 24.3 ± 7.9 MPa) vs. smear-layer-covered dentine (Adper Easy Bond 26.9 ± 6.2 MPa; iBond Self-Etch 17.6 ± 4.3 MPa). Adper Easy Bond showed lower nanoleakage than iBond Self-Etch, irrespective of preliminary etching. The results of this study support the use of phosphoric acid etching before the application of one-step self-etch adhesive systems. [source] Gene expression and dental enamel structure in developing mouse incisorEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2010Amer Sehic Sehic A, Risnes S, Khan Q-E-S, Khuu C, Osmundsen H. Gene expression and dental enamel structure in developing mouse incisor. Eur J Oral Sci 2010; 118: 118,130. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci At the mouse incisor tip the initially differentiated ameloblasts produce a thin, prism-free enamel, while further apically, in the immediate adjacent segment, the enamel thickness increases and the four-layered enamel of mouse incisor is formed. Comparative gene-expression profiling was carried out on RNA isolated from these two segments of incisor tooth germs at embryonic day (E)17.5 and at postnatal days (P)0, 1, 2, and 10 using microarrays to measure messenger RNA (mRNA) and microRNA (miRNA) species present in the segments. Validation of expression data was achieved using real-time reverse transcription,polymerase chain reaction (RT-PCR) and western blotting. Bioinformatic data suggested enhanced cellular apoptosis in the incisal tip segment, which, together with diminished expression of the Amelx and Enam genes, may contribute to the production of the thin enamel seen in this tooth segment. For genes exhibiting higher levels of expression in the adjacent segment where complex enamel is being formed, bioinformatic analysis suggested significant associations with cellular functions involving the actin cytoskeleton, cellular development, morphology, and movement. This is suggested to reflect that ameloblasts with Tomes' process are being organized in transverse rows, facilitating the transverse movement that results in prism decussation in the inner enamel of the adjacent segment. Bioinformatic analysis of miRNA expression data lends support to these suggestions. [source] Enamel microhardness and bond strengths of self-etching primer adhesivesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2010Olabisi A. Adebayo Adebayo OA, Burrow MF, Tyas MJ, Adams GG, Collins ML. Enamel microhardness and bond strengths of self-etching primer adhesives. Eur J Oral Sci 2010; 118: 191,196. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci The aim of this study was to determine the relationship between enamel surface microhardness and microshear bond strength (,SBS). Buccal and lingual mid-coronal enamel sections were prepared from 22 permanent human molars and divided into two groups, each comprising the buccal and lingual enamel from 11 teeth, to analyze two self-etching primer adhesives (Clearfil SE Bond and Tokuyama Bond Force). One-half of each enamel surface was tested using the Vickers hardness test with 10 indentations at 1 N and a 15-s dwell time. A hybrid resin composite was bonded to the other half of the enamel surface with the adhesive system assigned to the group. After 24 h of water storage of specimens at 37º°C, the ,SBS test was carried out on a universal testing machine at a crosshead speed of 1 mm min,1 until bond failure occurred. The mean ,SBS was regressed on the mean Vickers hardness number (VHN) using a weighted regression analysis in order to explore the relationship between enamel hardness and ,SBS. The weights used were the inverse of the variance of the ,SBS means. Neither separate correlation analyses for each adhesive nor combined regression analyses showed a significant correlation between the VHN and the ,SBS. These results suggest that the ,SBS of the self-etch adhesive systems are not influenced by enamel surface microhardness. [source] Distribution and structure of the initial dental enamel formed in incisors of young wild-type and Tabby miceEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2009Amer Sehic Mouse incisor enamel can be divided into four layers: an inner prism-free layer; an inner enamel with prism decussation; outer enamel with parallel prisms; and a superficial prism-free layer. We wanted to study how this complex structural organization is established in the very first enamel formed in wild-type mice and also in Tabby mice where enamel coverage varies considerably. Unworn incisors from young female wild-type and Tabby mice were ground, etched, and analyzed using scanning electron microscopy. In both wild-type and Tabby mice, establishment of the enamel structural characteristics in the initially formed enamel proceeded as follows, going from the incisal tip in an apical direction: (i) a zone with prism-free enamel, (ii) a zone with occasional prisms most often inclined incisally, and (iii) a zone where prism decussation was gradually established in the inner enamel. The distribution of enamel in Tabby mice exhibited considerable variability. The sequence of initial enamel formation in mouse incisors mimics development from a primitive (prism-free) structure to an evolved structure. It is suggested that genes controlling enamel distribution are not associated with genes controlling enamel structure. The control of ameloblast configuration, life span, organization in transverse rows, and movement is important for establishing the characteristic mature pattern of mouse incisor enamel. [source] Consequences for enamel development and mineralization resulting from loss of function of ameloblastin or enamelinEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2009Charles E. Smith Although the nonamelogenin proteins, ameloblastin and enamelin, are both low-abundance and rapidly degrading components of forming enamel, they seem to serve essential developmental functions, as suggested by findings that an enamel layer fails to appear on teeth of mice genetically engineered to produce either a truncated form of ameloblastin (exons 5 and 6 deleted) or no enamelin at all (null). The purpose of this study was to characterize, by direct micro weighing, changes in enamel mineralization occurring on maxillary and mandibular incisors of mice bred for these alterations in nonamelogenin function (Ambn+/+, +/,5,6, ,5,6/,5,6, Enam+/+, +/, ,,/,). The results indicated similar changes to enamel-mineralization patterns within the altered genotypes, including significant decreases by as much as 50% in the mineral content of maturing enamel from heterozygous mice and the formation of a thin, crusty, and disorganized mineralized layer, rather than true enamel, on the labial (occlusal) surfaces of incisors and molars along with ectopic calcifications within enamel organ cells in Ambn,5,6/,5,6 and Enam,/, homozygous mice. These findings confirm that both ameloblastin and enamelin are required by ameloblasts to create an enamel layer by appositional growth as well as to assist in achieving its unique high level of mineralization. [source] Oral bacterial adhesion forces to biomaterial surfaces constituting the bracket,adhesive,enamel junction in orthodontic treatmentEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2009Li Mei Bacterial adhesion to biomaterial surfaces constituting the bracket,adhesive,enamel junction represents a growing problem in orthodontics, because bacteria can adversely affect treatment by causing demineralization of the enamel surface around the brackets. It is important to know the forces with which bacteria adhere to the surfaces of these junction materials, as the strength of these forces will determine how easy it will be to remove the bacteria. We compared the adhesion forces of five initially colonizing and four cariogenic strains of bacteria to an orthodontic adhesive, stainless steel, and enamel, with and without a salivary conditioning film. Adhesion forces were determined using atomic force microscopy and a bacterial probe. In the absence of a salivary conditioning film, the strongest bacterial adhesion forces occurred to the adhesive surface (,2.9 to ,6.9 nN), while adhesion forces to the enamel surfaces were lowest (,0.8 to ,2.7 nN). In the presence of a salivary conditioning film, adhesion forces were reduced strongly, to less than 1 nN, and the differences between the various materials were reduced. Generally, however, initial colonizers of dental hard surfaces presented stronger adhesion forces to the different materials (,4.7 and ,0.6 nN in the absence and presence of a salivary conditioning film, respectively) than cariogenic strains (,1.8 and ,0.5 nN). [source] Tin-containing fluoride solutions as anti-erosive agents in enamel: an in vitro tin-uptake, tissue-loss, and scanning electron micrograph studyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2009Nadine Schlueter Tin-containing fluoride solutions can reduce erosive tissue loss, but the effects of the reaction between tin and enamel are still not clear. During a 10-d period, enamel specimens were cyclically demineralized (0.05 M citric acid, pH 2.3, 6 × 5 min d,1) and remineralized (between the demineralization cycles and overnight). In the negative-control group, no further treatment was performed. Three groups were treated (2 × 2 min d,1) with tin-containing fluoride solutions (400, 1,400 or 2,100 ppm Sn2+, all 1,500 ppm F,, pH 4.5). Three additional groups were treated with test solutions twice daily, but without demineralization. Tissue loss was determined profilometrically. Energy-dispersive X-ray spectroscopy was used to measure the tin content on and within three layers (10 ,m each) beneath the surface. In addition, scanning electron microscopy was conducted. All test preparations significantly reduced tissue loss. Deposition of tin on surfaces was higher without erosion than with erosion, but no incorporation of tin into enamel was found without demineralization. Under erosive conditions, both highly concentrated solutions led to the incorporation of tin up to a depth of 20 ,m; the less-concentrated solution led to small amounts of tin in the outer 10 ,m. The efficacy of tin-containing solutions seems to depend mainly on the incorporation of tin into enamel. [source] The location and characteristics of two populations of dental pulp cells affect tooth developmentEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2009Yoshinori Sumita This study investigated the characteristics of two dental pulp cell populations during the early stages of crown formation in porcine teeth. A transplantation method was developed to reproduce epithelial cell,mesenchymal cell interactions during odontogenesis (tooth development). The technique allowed two types of cells/tissue to be combined in vivo. Populations of cells localized in the cervical loop epithelium region, dental pulp horn, and dental pulp core chambers were isolated and dissociated into single cells. Each population was examined for its gene-expression pattern using both semiquantitative and quantitative reverse transcription,polymerase chain reaction (RT-PCR) analyses, and for its tissue-formation capability by combining the cervical loop epithelial cells with either pulp horn cells or pulp core cells on biodegradable collagen scaffolds that were subsequently examined using histology and immunohistology. Gene-expression patterns showed that pulp horn cells were more mature than pulp core cells. Cervical loop epithelial cells combined with pulp horn cells mainly reconstituted dentin,cementum structures. By contrast, cervical loop epithelial cells combined with pulp core cells reconstituted enamel,dentin structures. These results suggest that mesenchymal cells residing in a specific location of the pulp possess a specific tissue-formation potential when combined with epithelial cells. [source] Micro-shear bond strengths and etching efficacy of a two-step self-etching adhesive system to fluorosed and non-fluorosed enamelEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2009Kanako Shida The purpose of this study was to evaluate the micro-shear bond strengths and the etching efficacy of a two-step self-etching adhesive system to fluorosed and non-fluorosed enamel. The extracted teeth, obtained from Australian and Japanese patients, were classified according to the severity of fluorosis, using the Thylstrup & Fejerskov index (TFI). Australian teeth were classified as mildly fluorosed (TFI = 1,3), whereas Japanese teeth were classified as non-fluorosed (TFI = 0). Resin composite was bonded to 20 enamel samples using Clearfil SE bond. The bonded samples were stressed at a crosshead speed of 1 mm min,1 to determine the micro-shear bond strength. To examine the etching efficacy of primer on fluorosed and non-fluorosed enamel, the enamel-surface pH values were directly measured using a micro pH sensor. The non-fluorosed enamel showed significantly higher bond strengths compared with the fluorosed enamel. There was a statistical difference between fluorosed and non-fluorosed enamel regarding the surface pH change before and after application of the Clearfil SE bond primer. The results from this study suggest that water fluoridation has an effect on the acid resistance of enamel surfaces when treated with a two-step self-etching adhesive system and that this effect leads to reduced bond strengths. [source] Ability of different restorative materials to prevent in situ secondary caries: analysis by polarized light-microscopy and energy-dispersive X-rayEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2008Thaís Cachuté Paradella Secondary caries is the main cause of direct restoration replacement. The purpose of this study was to analyze enamel adjacent to different restorative materials after in situ cariogenic challenge using polarized-light microscopy (PLM), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDS). Twelve volunteers, with a low level of dental plaque, a low level of mutans streptococci, and normal salivary flow, wore removable palatal acrylic appliances containing enamel specimens restored with Z250 composite, Freedom composite, Fuji IX glass-ionomer cement, or Vitremer resin-modified glass-ionomer for 14 days. Volunteers dripped one drop of 20% sucrose solution (n = 10) or distilled water (control group) onto each specimen 8 times per day. Specimens were removed from the appliances and submitted to PLM for examination of the lesion area (in mm2), followed by dehydration, gold-sputtering, and submission to SEM and EDS. The calcium (Ca) and phosphorus (P) contents were evaluated in weight per cent (%wt). Differences were found between Z250 and Vitremer, and between Z250 and FujiIX, when analyzed using PLM. Energy-dispersive X-ray analysis results showed differences between the studied materials regarding Ca %wt. In conclusion, enamel adjacent to glass-ionomer cement presented a higher Ca %wt, but this material did not completely prevent enamel secondary caries under in situ cariogenic challenge. [source] Effect of stannous fluoride toothpaste on erosion-like lesions: an in vivo studyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2006Alix Young It has recently been shown that stannous fluoride (SnF2), in the form of aqueous solutions and as toothpaste, can reduce the dissolution of enamel in erosive acids in vitro and in situ. The aim of this study was to compare the effect of toothpastes containing SnF2 or NaF on enamel dissolution using an in vivo model. Four healthy anterior teeth in each subject (n = 20) were exposed to diluted citric acid (100 mmol l,1 or 10 mmol l,1) applied using a peristaltic pump (5 ml @7 ml min,1) and the acid was collected in a test tube before and after application of the respective toothpastes (etch I and etch II). Toothpaste was applied to the labial surfaces with a soft brush (four applications, each of 1-min duration), with gentle water rinsing between applications. Each subject had one pair of teeth treated with each of the test toothpastes. Enamel dissolution was examined by assessment of calcium content in the citric acid applied before and after the treatment with toothpaste. The results indicate that the SnF2 toothpaste markedly reduced the dissolution of teeth in vivo (etch II < etch I), whereas the NaF toothpaste provided no protection (etch II > etch I). Toothpaste appears to be an acceptable vehicle for SnF2 and maintains the dissolution-reducing effect exhibited by aqueous solutions of this fluoride salt. [source] | ||||||||||||||||||||||||||||||||||||||||