Factors Involved in the Perception of Enamel Dyschromic Lesions—A Questionnaire-Based Study

Dyschromic lesions (DLs) of tooth enamel are common disorders, with multiple etiologies and various clinical forms, that raise public health concerns. This study aimed to determine the factors that influence the perception of DLs and to assess the perceived need for dental treatment in various clinical cases. A paper-based questionnaire with attached images of frontal teeth exhibiting different DLs was distributed to patients, dental students, and dentists. A total of 383 volunteers participated in this study, and their answers were statistically described and analyzed. This study found that in cases with multiple, well-demarcated areas of opacities associated with diffuse opacities on neighboring teeth, most respondents noticed and reported only the most severe lesions, disregarding the minor ones. The contrast of the lesion with the color of the substrate influenced the overall perception and a significant correlation between these two variables was found. However, the color of the DLs did not significantly impact the overall perception of the lesions. A higher overall perception of DLs was significantly correlated with a favorable opinion regarding the need for treatment. Furthermore, gender and medical background were significantly associated with the overall perception of DLs.

Disruption of the adh (acetoin dehydrogenase) operon has wide-ranging effects on Streptococcus mutans growth and stress response

The agent largely responsible for initiating dental caries, Streptococcus mutans produces acetoin dehydrogenase that is encoded by the adh operon. The operon consists of the adhA and B genes (E1 dehydrogenase), adhC (E2 lipoylated transacetylase), adhD (E3 dihydrolipoamide dehydrogenase), and lplA (lipoyl ligase). Evidence is presented that AdhC interacts with SpxA2, a redox-sensitive transcription factor functioning in cell wall and oxidative stress responses. In-frame deletion mutations of adh genes conferred oxygen-dependent sensitivity to slightly alkaline pH (pH 7.2-7.6), within the range of values observed in human saliva. Growth defects were also observed when glucose or sucrose served as major carbon sources. A deletion of the adhC orthologous gene, acoC gene of Streptococcus gordonii , did not result in pH sensitivity or defective growth in glucose and sucrose. The defects observed in adh mutants were partially reversed by addition of pyruvate. Unlike most 2-oxoacid dehydrogenases, the E3 AdhD subunit bears an N-terminal lipoylation domain nearly identical to that of E2 AdhC. Changing the lipoyl domains of AdhC and AdhD by replacing the lipoate attachment residue, lysine to arginine, caused no significant reduction in pH sensitivity but the adhDK43R mutation eliminating the lipoylation site resulted in an observable growth defect in glucose medium. The adh mutations were partially suppressed by a deletion of rex , encoding an NAD + /NADH-sensing transcription factor that represses genes functioning in fermentation. spxA2 adh double mutants show synthetic growth restriction at elevated pH and upon ampicillin treatment. These results suggest a role for Adh in stress management in S. mutans . IMPORTANCE Dental caries is often initiated by Streptococcus mutans , which establishes a biofilm and a low pH environment on tooth enamel surfaces. The current study has uncovered vulnerabilities of S. mutans mutant strains that are unable to produce the enzyme complex, acetoin dehydrogenase (Adh). Such mutants are sensitive to modest increases in pH to 7.2-7.6, within the range of human saliva, while a mutant of a commensal Streptococcal species is resistant. The S. mutans adh strains are also defective in carbohydrate utilization and are hypersensitive to a cell wall-acting antibiotic. The studies suggest that Adh could be a potential target for interfering with S. mutans colonization of the oral environment.

Developmental Dental Defects in Permanent Teeth Resulting from Trauma in Primary Dentition. A Systematic Review

The objective was to determine whether trauma in primary dentition causes alterations in the development of permanent dentition. Searches were made in May 2020 using PubMed, MEDLINE, MEDES, Scopus, Lilacs, and Embase. Papers in English, German, and Spanish, without restrictions in the year of publication, were included. The quality of the studies was analyzed using the NOS Scale. The search retrieved 537 references, and seven studies were included for a qualitative analysis. The results showed that trauma to a deciduous tooth can damage the bud of the permanent tooth. Enamel discoloration and/or hypoplasia were the most common sequelae in the permanent teeth after trauma to the primary predecessor. The type and severity of sequelae in the permanent tooth are associated with the development phase of the bud. Children with trauma of their primary teeth should receive checkups until the eruption of the permanent teeth for the early diagnosis and treatment of possible sequelae. Intrusion of the primary tooth was the trauma that caused the most damage and enamel alterations the most frequent sequelae.

Novel Mutations in GPR68 and SLC24A4 Cause Hypomaturation Amelogenesis Imperfecta

Amelogenesis imperfecta (AI) is a rare genetic condition affecting the quantity and/or quality of tooth enamel. Hypomaturation AI is characterized by brownish-yellow discoloration with increased opacity and poorly mineralized enamel prone to fracture and attrition. We recruited three families affected by hypomaturation AI and performed whole exome sequencing with selected individuals in each family. Bioinformatic analysis and Sanger sequencing identified and confirmed mutations and segregation in the families. Family 1 had a novel homozygous frameshift mutation in GPR68 gene (NM_003485.3:c.78_83delinsC, p.(Val27Cysfs*146)). Family 2 had a novel homozygous nonsense mutation in SLC24A4 gene (NM_153646.4:c.613C>T, NP_705932.2:p.(Arg205*)). Family 3 also had a homozygous missense mutation in SLC24A4 gene which was reported previously (c.437C>T, p.(Ala146Val)). This report not only expands the mutational spectrum of the AI-causing genes but also improves our understanding of normal and pathologic amelogenesis.

In situ oxygen isotope micro-analysis of faunal material and human teeth using a SHRIMP II: a new tool for palaeo-ecology and archaeology

A Sensitive High Resolution Ion MicroProbe (SHRIMP II) has been used to make high spatial resolution in situ micro-analyses of oxygen isotopes in fish otoliths, and teeth from fossil herbivores and a Neanderthal. Large intra-tooth variations in the oxygen isotopic composition (up to 9&) were observed in the enamel of herbivores from the Neanderthal fossil site of Payre, consistent with preservation of seasonal cyclicity. The range of isotopic compositions observed in Neanderthal tooth enamel was much smaller (w3&), possibly the result of a longer enamel maturation time averaging out variability. An archaeological otolith from a Preceramic site in Northern Peru exhibited marked changes in δ18O over life, due either to the fish occasionally migrating from the sea to a lower salinity habitat, or to short-lived rises in sea water temperature. A fish otolith from Australia’s Willandra Lakes World Heritage Area showed clear seasonal variations, but also a general trend towards isotopically heavier and more saline water, as indicated by higher δ18O and Sr/Ca values resulting from increased evaporation. The results of these case studies are compared to results of oxygen isotope analysis using more conventional methods and demonstrate the ability of the SHRIMP II to provide precise high spatial resolution in-situ oxygen isotope analyses of a variety of biogenic materials. This approach has major advantages over conventional methods. It can provide rapid, micro-scale isotopic analyses of sub-permil precision without the need for chemical preparation of the sample.

Infrared Clinical Enamel Crack Detector Based on Silicon CCD and Its Application: A High-Quality and Low-Cost Option

Enamel cracks generated in the anterior teeth not only affect the function but also the aesthetics of the teeth. Chair-side tooth enamel crack detection is essential for clinicians to formulate treatment plans and prevent related dental disease. This study aimed to develop a dental imaging system using a near-IR light source to detect enamel cracks and to investigate the relationship between anterior enamel cracks and age in vivo. A total of 68 subjects were divided into three groups according to their age: young, middle, and elderly. Near-infrared radiation of 850 nm was used to identify enamel cracks in anterior teeth. The results of the quantitative examination showed that the number of enamel cracks on the teeth increased considerably with age. For the qualitative examination, the results indicated that there was no significant relationship between the severity of the enamel cracks and age. So, it can be concluded that the prevalence of anterior cracked tooth increased significantly with age in the young and middle age. The length of the anterior enamel cracks tended to increase with age too; however, this result was not significant. The silicon charge-coupled device (CCD) with a wavelength of 850 nm has a good performance in the detection of enamel cracks and has very good clinical practicability.