6-year Molars Research Articles

Pathogenesis of Molar Hypomineralisation: Aged Albumin Demarcates Chalky Regions of Hypomineralised Enamel.

Molar hypomineralisation (MH) is becoming globally recognised as a significant public health problem linked to childhood tooth decay. However, with causation and pathogenesis unclear after 100 years of investigation, better pathological understanding is needed if MH is to become preventable. Our studies have implicated serum albumin in an extracellular pathomechanism for chalky enamel, opposing longheld dogma about systemic injury to enamel-forming cells. Hypothesising that chalky enamel arises through developmental exposure to serum albumin, this study used biochemical approaches to characterise demarcated opacities from 6-year molars. Addressing contradictory literature, normal enamel was found to completely lack albumin subject to removal of surface contamination. Querying surface permeability, intact opacities were found to lack salivary amylase, indicating that “enamel albumin” had become entrapped before tooth eruption. Thirdly, comparative profiling of chalky and hard-white enamel supported a dose-response relationship between albumin and clinical hardness of opacities. Moreover, albumin abundance delineated chalky enamel from white transitional enamel at opacity borders. Finally, addressing the corollary that enamel albumin had been entrapped for several years, clear signs of molecular ageing (oxidative aggregation and fragmentation) were identified. By establishing aged albumin as a biomarker for chalky enamel, these findings hold methodological, clinical, and aetiological significance. Foremost, direct inhibition of enamel-crystal growth by albumin (here termed “mineralisation poisoning”) at last provides a cogent explanation for the clinical presentation of demarcated opacities. Together, these findings justify pursuit of an extracellular paradigm for the pathogenesis of MH and offer exciting new prospects for alleviating childhood tooth decay through medical prevention of MH.

Pathogenesis of Molar Hypomineralisation: Hypomineralised 6-Year Molars Contain Traces of Fetal Serum Albumin.

Molar Hypomineralisation (MH) is gaining cross-sector attention as a global health problem, making deeper enquiry into its prevention a research priority. However, causation and pathogenesis of MH remain unclear despite 100 years of investigation into “chalky” dental enamel. Contradicting aetiological dogma involving disrupted enamel-forming cells (ameloblasts), our earlier biochemical analysis of chalky enamel opacities implicated extracellular serum albumin in enamel hypomineralisation. This study sought evidence that the albumin found in chalky enamel reflected causal events during enamel development rather than later association with pre-existing enamel porosity. Hypothesising that blood-derived albumin infiltrates immature enamel and directly blocks its hardening, we developed a “molecular timestamping” method that quantifies the adult and fetal isoforms of serum albumin ratiometrically. Applying this novel approach to 6-year molars, both isoforms of albumin were detectable in 6 of 8 chalky opacities examined (corresponding to 4 of 5 cases), indicating developmental acquisition during early infancy. Addressing protein survival, in vitro analysis showed that, like adult albumin, the fetal isoform (alpha-fetoprotein) bound hydroxyapatite avidly and was resistant to kallikrein-4, the pivotal protease involved in enamel hardening. These results shift primary attention from ameloblast injury and indicate instead that an extracellular mechanism involving localised exposure of immature enamel to serum albumin constitutes the crux of MH pathogenesis. Together, our pathomechanistic findings plus the biomarker approach for onset timing open a new direction for aetiological investigations into the medical prevention of MH.

Study Regarding the Elastic Impression Biomaterials Dimensional Stability

In order to have an accurate impression, dimensional modifications must be under control throughout the impression stages, considering they are highly influenced by the variability level during polymerization.The factors with an influence on dimensional stability are:impression material width, tensile modulus, temperature during the imprinting process, storage humidity, the time lapse between imprinting and casting. The study focuses on dimensional modifications of varied elastic impression materials, considering both testing and impression techniques are done in similar conditions in order to assess accurately the behaviour of varied impression materials.Material and methods:The study was based on a laboratory simulation of a clinical situation. There were used two 6-year maxillary molars in the position they have in the oral cavity. A 3 mm wax layer was added during the next stage its width being checked with an Ivoclar mechanical vernier. The surface parallelism was subsequently checked using a parallelograph and there was taken an individual tray made of photopolymer acrylic. The measurements of this study were limited to the linear dimension, being observed the changes occurred in one direction, although contraction is a volumetric modification.The statistic assessment of the measurement data obtained in the case of the same type of addition silicon materials recorded an increase of the volumetric contraction type in dry environment and in longer time intervals.The addition materials were significantly superior in terms of contraction time, as compared to the previous case, granting higher accuracy to the end product. The Silagum Light presented an increased volumetric contraction in moist environment, the contraction being more significant in longer time intervals. The Xantopren L blue material has a reduced deformation gradient in less than 48 h.

Nationwide 2.5-Year School-Based Public Health Intervention Program Designed to Reduce the Incidence of Caries in Children of Grenada

This paper describes an innovative public health intervention, called ‘Smile Grenada', targeting the oral health of children in Grenada utilizing the resources of a US dental school, several oral health care companies, local governmental and public health authorities, and Grenadian school personnel. Methods: Preintervention visual/tactile caries examinations were collected from 1,092 schoolchildren (mean age 9.9 years, standard deviation, SD = 3.7) in 2010. The intervention included: (1) classroom-based toothbrushing with fluoridated toothpaste, (2) fluoride varnish applied by trained dental students, teachers and local providers 3 times a year and (3) glass ionomer sealants placed on first permanent molars in children aged 6-8 years. Postintervention data were collected in May, 2013 (n = 2,301, mean age 9.8 years, SD = 3.7). Decayed and demineralized surfaces were examined for the whole sample and decay/demineralization and sealant retention on 6-year molars were examined separately (ages 6-8 in 2013 cohort). Results: The number of decayed/demineralized surfaces declined across all age groups. The average number of decayed surfaces dropped from 9 at baseline to just over 6 (F_{1, 3,393} = 69.8, p < 0.0001) and the average number of demineralized surfaces dropped from 6 to less than 2 (1.8 surfaces; F_{1, 3,393} = 819.0, p < 0.0001). For children aged 6-8 years, there were statistically significantly fewer decayed surfaces (t_{1, 2,086} = 12.40, p < 0.0001; mean baseline 0.93, SD = 1.75; mean follow-up 0.23, SD = 0.83) and demineralized surfaces (t_{1, 2,086} = 19.7, p < 0.0001; mean baseline 2.11, SD = 2.74; mean follow-up 0.50, SD = 0.97) on 6-year molars. The Smile Grenada program successfully demonstrated a locally sustainable model for improving oral health in children in a developing country.

CONSERVAREA STRUCTURII DURE DENTARE PRIN DIAGNOSTIC MODERN UTILIZÂND LASER CU LUMINĂ FLUORESCENTĂ (DIAGNODENT PEN 2190) ŞI TRATAMENT MINIM INVAZIV – CAZ CLINIC

Caries diagnosis should be done in the early stages in order to preserve long-term hard dental structures. In addition to that, the cavity lesions treatment should use adhesive materials for crown obturation which allow strictly carious lesion removal and do not require the creation of retention forms, involving an additional sacrifice of dental tissues, thus jeopardizing the tooth resistance. The study presents the case of a 9 years old, male patient who had multiple cavities in the mixed dentition. The designed treatment plan aimed, firstly, at assessing the degree of damage, trough cavities, of the four 6-year molars existing on the arcades and the choice of techniques and materials for coronal restoration following ART concept (Atraumatic Restorative Treatement). Cavities diagnosis was made by combining conventional methods (visual inspection, inspection and palpation by probe, retro alveolar radiography and OPG) and modern methods (laser fluorescence DIAGNOdent Pen 2190). The prime molars 36, 46 treatment consisted in the creation of some VI class cavities, than plugged with glassionomer cement (Fuji IX) due to increased and prolonged release of fluoride, while the 16, 26 molars treatment was achieved by incipient lesions remineralization by topical application of a fluoride varnish containing 5% sodium fluoride (Profluorid varnish, Voco GmbH).

Correlation between the frequency of eruption disorders for first permanent molars and the occurrence of malocclusions in early mixed dentition

We analyzed the incidence of eruption disorders in 6-year molars during the first phase of mixed dentition, and then determined the risks for later dental arch development according to specific combinations of orthodontic malocclusions. We, thus, aimed to derive potential conclusions for preventative orthodontics. In this cross-sectional study, 8,041 kindergarten and school children with early mixed dentition were randomly selected and clinically examined. Examinations were performed in two consecutive years during the standard dental screening that school children undergo. The average age was 6.9 years. We defined an eruption of the 6-year molars as being disturbed when (1) the distal cusps had erupted further than the mesial cusps, (2) the mesial inclination of the occlusal surface revealed disturbed eruption, and (3) the 6-year molar had erupted below the second primary molar. Disturbed eruption of the first permanent molars was observed in 102 of these children. The upper 6-year molars were affected more often (88.5%) than the lower molars. Bilateral disturbed eruption of the upper molars was the most frequent combination of symptoms found. Although disturbed eruption was diagnosed most often in 6- and 7-year-old children, the 8-year-old children presented 20% of the eruption disorders. Moreover, 72.6% of the children with disturbed eruption presented at least one additional orthodontic malocclusion. Crowding (p ≤ 0.001), lateral malocclusions (p ≤ 0.001), and mandibular prognathism (p = 0.009) were present significantly more often in children with disturbed eruption of 6-year molars. Delayed eruption and false direction of eruption of the upper 6-year molars may-already at an early stage-raise the likelihood of problems during later dental arch development, such as crowding in the sagittal and transverse directions or Class III developments.

The relationship between caries in the primary dentition at 5 years of age and permanent dentition at 10 years of age – a longitudinal study

To explore a possible relationship between the caries experience and pattern in the primary dentition at 5 years of age and the permanent dentition at 10 years of age. Further, to examine the possibility of predicting children in a caries-risk group at 5 years verified at 10 years of age. A sample of 186 children (90 males) were clinically examined as 5-year-olds and re-examined as 10-year-olds by calibrated dentists. A five-graded diagnostic system including enamel caries was used. Bitewing radiographs were taken. A true risk group of children at 10 years were defined as those with at least one dentin or filled lesion on the mesial surface of 6-year molars, and/or on incisors, and/or total DMFS (decayed, missing, and filled surfaces) more than 1 SD above the mean. The prediction was measured in terms of OR (odds ratio), sensitivity/specificity, and receiver operating characteristic curves. Statistically significant correlations (r=0.5) were found between the caries experience in the two dentitions as well as between the primary second molars at baseline and the permanent teeth at 10 years. 'Primary second molars' and 'all primary molars' were the most powerful predictors for allocation into the risk group (24% of the sample). The highest achieved sum of sensitivity and specificity, 148%, was attained at a cut-off point above two carious surfaces in enamel and/or dentin in primary second molars. Statistically significant relationship in disease between the dentitions was found. More than two surfaces with caries experience in primary second molars are suggested as a clinically useful predictor at 5 years of age for being at high risk at age 10.

Anchorage quality of deciduous molars versus premolars for molar distalization with a pendulum appliance

The aim of this study was to assess dental anchorage qualities when the pendulum appliance is used for distal molar movement. Thirty adolescents in various dentition stages received a modified pendulum appliance with a distal screw and a specially preactivated pendulum spring for bilateral molar distalization in the maxilla. The subjects were subcategorized into 3 groups of 10 according to the dental anchorage used: deciduous molars, premolars and deciduous molars, or only premolars. Dentoalveolar effects and side effects in the anchorage unit and in the molar area were determined by cephalometric analysis. Statistical analysis of the measurements showed significant differences between groups in the extent of molar distalization and the resulting incisor protrusion. Distal tipping of the 6-year molars was significantly less severe (2.3 degrees +/- 1.58 degrees to the palatal plane and 2.55 degrees +/- 1.52 degrees to the anterior cranial base) in patients with premolar anchorage than in those with deciduous molar anchorage (6.15 degrees +/- 3.42 degrees and 6.35 degrees +/- 3.46 degrees ). Incisor protrusion was significantly more pronounced in patients with deciduous molar anchorage (2.75 +/- 1.4 mm) than in the other 2 groups (1.65 +/- 0.82 mm, mixed deciduous molar and premolar anchorage, and 1.75 +/- 0.75 mm, premolar anchorage). Additionally, incisor protrusion was translatory compared with controlled tipping in subjects with deciduous molar anchorage or premolar and deciduous molar anchorage. Deciduous molars and premolars can be used for anchorage for molar distalization with a pendulum appliance; however, anchorage with premolars only results in the least pronounced dentoalveolar side effects. The anchorage quality of deciduous molar and mixed deciduous molar/premolar anchorage is limited.

Kabuki syndrome: description of dental findings in 8 patients.

The cardinal features of Kabuki (Niikawa-Kuroki) syndrome (KS) include characteristic facial dysmorphic features, mild to moderate mental deficiency, skeletal abnormalities, dermatoglyphic abnormalities, and postnatal growth retardation. We identified 8 patients with KS in a genetics clinic over the past 5 years. All were Caucasians, except for 2 who were of mixed Aboriginal and Caucasian descent. All had the facial gestalt, the dermatoglyphic abnormalities characteristic of the syndrome, and developmental delay. Dental abnormalities of permanent teeth were seen in all 8 cases; 6 had missing lower incisors. Five patients had uniquely abnormal upper incisor teeth shape; the upper incisors had a 'flat head' screwdriver-shaped appearance. Other dental abnormalities included missing lower lateral incisors, missing second premolars, and ectopic upper 6-year molars. We believe the presence of the unique dental findings will prove useful in the diagnostic assessment of individuals with KS.

Occlusion studies after extraction of 6-year molars

An Hand von 45 kieferorthopadischen Patienten wurde die Okklusion nach der Extraktion aller Sechsjahrmolaren untersucht.

Incidence and consequences of the early loss of the 6-year molars

Nach vor allem aus eigenen statistischen Erhebungen entnommenen Angaben uber die Haufigkeit des fruhzeitigen Verlustes erster Molaren werden die Folgezustande aufgezeigt, die dieser Verlust nach sich zieht. An Hand der Analyse eines eigenen Patientengutes wird versucht, den fur die weitere Gebisentwicklung gunstigsten Zeitpunkt der Entfernung erster Molaren zu bestimmen und andere ausere Umstande dabei zu berucksichtigen.

Sequelae of the extraction of 6-year molars

Sequelae of the extraction of 6-year molars

Study on the caries incidence in 6-year molars from the orthodontic viewpoint

Study on the caries incidence in 6-year molars from the orthodontic viewpoint

Studies on mineralized dental tissues. XV. Mineral pattern of dentine.

Abstract In this investigation the following problems are treated: 1. 1. Does any relation exist in the present Swedish material between caries and the mineral pattern of the dentine? 2. 2. Do different types of teeth differ in their mineral pattern? 3. 3. Does the mineral pattern of dentine vary on a geographical basis? 4. 4. We have hoped to indicate normal values for the various types of mineral pattern in different primary teeth and in 6-year molars. The analyses showed: 1. 1. That no marked relation could be found between the extent of caries and the mineral pattern. 2. 2. That different types of teeth showed great variations in respect of the extent of the types of mineral pattern. By using a standardized scale of marking, significant differences could be shown. 3. 3. That a comparison between town and country showed a significant difference, mineralization disturbances being more common in the towns. 4. 4. Normal values for mineral pattern of dentine from the present study are shown in Fig. 4.

Promoting Dental Health Care

RODEO TRAINS, films, and plastic-tooth jewelry generated active participation in a dental health campaign fo,r primary school children in Stevens County, Wash., during 1959. The drive, conducted by the Stevens County Health Department, aimed at promoting remedial action for children in need of dental attention. The campaign originated in a request from the county department to the Washington State Health Department for help in planning a program fo,r children who had not been covered in a previous drive. Rapid dental inspections were being made periodically throughout the schools in the State by members o,f the local dental societies, each time renewing the intereist of parents, teachers, and children in dental health. Here was the opportunity to channel that renewed interest into remedial action. The State health department came through with help in the way of advice on program design, metho,ds of carrying it out, and presentation of reisults within a statistical matrix. Plans drawn up under the direction of Dr. Merle B. Snyder, Stevens County health officer, called for a program spanning the school year. The focus was on the pupils' 6-year permanent molars, because these four teeth are important in the formation and development of the dental arch and have high decay risk. They are the first permanent teeth, arriving early in the primary school experience of the child. Followup by the county public health nurses, May Alm and Belle Howard, was scheduled during the program year with the cooperation of the individual schools. Early investigation showed conditions that augured success. The 6-year molars among children in the county frequently required dental attention, and, in many instances, neglect came only from ignorance of the need for repair or from apathy thought to be correctible. The initial steps were directed toward alerting adults, especially teachers, and children to the need for dental care. The techniques included publicizing the program in the local newspapers, describing it to teachers, and supplying program material to the schools, where the message was then carried to the children. Next, Dr. J. H. Kennedy, a local practicing dentist, conducted a rapid dental examination in the nine schools, with emphasis on repair needs of the 6-year molars. Other defects were noted too, and any fissure or pit requiring treatment was classified as a cavity. As the drive gained momentum, the primary effort to stimulate motivation was applied to the children themselves. They participated actively by joining a rodeo train or a variation of the idea. The train is a cardboard engine with cars which the child boards with a ticket showing that he has molars intact or cared for by the dentist. The teacher was careful to allow those children who had lost their molars or who could not get repairs to get on eventually. Children riding the train were handed plastic 6-year molars to wear. Toothbrushes were also distributed. Other stimulating features were the filmstrip about Elmer-the little boy who learned to like his dentist-and educational materials, films, and slides from the local and Dr. Skinner is chief of the division of local health services in the Washington State Department of Health at Seattle, in which Mr. Sabotta is a statistical analyst in the staff services analysis unit.

Caries control: Its influence and effects on malocclusion

It is generally conceded that fluorides found within the municipal drinking water supply lessen the percentage of decay in both the deciduous and the permanent dentures. The percentages of reduction are much higher in those individuals who have been born and have lived continuously in areas of fluorinated water. It is generally accepted that 1.0 to 1.5 p.p.m. is most ideal for this purpose. That quantity produces little or no fluorosis. Maximum results accrue when individuals receive optimum concentration of fluorides from conception to adulthood. In the same areas of optimum concentration of 1.0 p.p.m. fluorides, incidence of malocclusion is reduced by 30 per cent, presumably due to the prolongation of the life and function of deciduous teeth and the subsequent permanent 6-year molars. A sincere appeal is made to the orthodontists to urge and assist the operative and preventive dentists in creating conditions in their communities that will reduce the ravages of decay.