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PubMed1991

Influence of posteruptive age of enamel on its susceptibility to artificial caries.

Epidemiologic studies and caries experiments with animals have suggested that caries susceptibility of teeth decreases with age. Observations on the changes in the dental tissues and their environment with age have pointed out that a process commonly referred to as 'posteruptive maturation' of the dental enamel may be responsible. To test this assumption 10 unerupted third molars and 56 erupted human premolar teeth of various posteruptive ages were subjected for 130 days to an acid gel for caries-like lesion formation in vitro. Sections of the teeth were examined with polarized light and 'contour maps' were drawn with the approximate porosity of the lesions. The results were: unerupted = 833 microns (+/- 261); erupted of posteruptive age 0-3 years = 561 microns (+/- 150), 4-10 years = 470 microns (+/- 136), 11-30 years = 459 microns (+/- 192) and over 30 years = 297 microns (+/- 89). These findings show a decrease in the susceptibility of enamel to artificial caries with increasing age, which was especially marked at and shortly after eruption. This may be explained by a completion of mineralization of the outer enamel at about eruption, by a maturation process of the outer enamel posteruptively and by a reduction in the permeability of enamel occurring through to old age. The fluoride content of the mid-coronal buccal surface enamel under study was found to decrease posteruptively with age, therefore not accounting for the decreasing caries susceptibility.

Adolescent↗

PubMed2004

Management of unerupted maxillary canines where no orthodontic treatment is planned; a survey of UK consultant opinion.

OBJECTIVE: To assess current consultant opinion on the management of impacted maxillary canines in patients for whom no orthodontic treatment is planned. DESIGN: Questionnaire survey. METHOD: Questionnaires were sent to all UK consultant orthodontists identified from the Consultant Orthodontists Group database. Follow-up questionnaires were sent to those who had not replied within 6 weeks. An overall response rate of 76% was achieved. RESULTS: Most consultants were in favor of intervention, with removal of the unerupted canine, although a significant minority suggested a conservative approach. Of the latter group, nearly all recommended radiographic monitoring, but there was little agreement regarding the frequency and duration of this. The risk of root resorption was stated to be the most important factor justifying monitoring. CONCLUSIONS: Significant variation was found amongst UK consultant orthodontists with regard to the management of impacted canines, where orthodontic treatment was not planned. The clinical and radiographic features, which the respondents stated would influence their decision to remove or leave the canine, were not those that existing research suggests as being the primary risk factors. It is suggested that, once the patient has passed the peak age for initiation of resorption, a more conservative approach may be appropriate.

Attitude of Health Personnel↗

PubMed1990

Relationship of abnormalities in dental and skeletal development in the osteopetrotic (os) rabbit.

Osteopetrosis is a metabolic bone disease characterized by reduced bone resorption of heterogenous cause. The rabbit mutation is lethal and exhibits ultrastructural aberrations in osteoclasts and osteoblasts together with hypocalcemia, hypophosphatemia and failure to be cured by bone marrow transplantation. We have studied dental abnormalities in mutants from birth to 3 wk using radiographic, cytologic and autoradiographic methods. Radiographs show hypoplasia of most teeth in mutants. The maxillary incisor is smaller and more curved and the mandibular incisor thin and straight compared to normal littermates. The first 3 molars in both arches are unerupted and of distorted shape while the last 2 are less affected. Microscopically areas of ankylosis of mutant incisors and the first 3 molars were commonly encountered even at birth. Osteoclasts were numerous. Autoradiograms of 3H-proline incorporation showed strong periosteal and weak endosteal labeling of bone in both mutants and normal littermates. Dentin labeling in mutant incisors and molars was not less than that in normal rabbits and sites of ankylosis in mutants exhibited labeling. These data indicate that osteopetrotic rabbits exhibit major aberrations in shape and eruption of incisors and most molars and that these effects are not due to lack of dentin formation. Early ankylosis, perhaps secondary to congenital reduction of bone resorption, appears to be the major cause of the dental abnormalities which are less severe in the youngest (posterior) teeth.

Animals↗

PubMed1993

Comparison of clinical treatment decisions with US National Institutes of Health consensus indications for lower third molar removal.

Treatment decisions about lower third molar surgery have important clinical and cost implications. Although indications for surgery have been the subject of a National Institutes of Health (NIH) consensus conference at which several unambiguous criteria were agreed, no prospective investigations have been carried out to compare clinic treatment decisions with these consensus criteria. Treatment decisions made by six Hospital Service oral surgeons were therefore evaluated for 72 consecutive patients (28 men, 44 women) aged 15-44 years (mean age 25 years), referred for lower third molar assessment. The presence of local disease; recurrent pericoronitis; caries not amenable to restorative measures; follicular cyst formation; internal/external resorption and periodontal disease was recorded by an independent observer immediately after treatment planning had been completed. Of the 139 third molars present, 55 were unerupted, 79 partially erupted and 5 fully erupted. Thirty patients had been scheduled for surgery under general anaesthesia (GA), 36 under local anaesthesia and six patients had not been scheduled for surgery. A total of 42 teeth, according to NIH consensus criteria, had no indications for removal, of which 27 had been scheduled for surgery. These excluded disease-free contralateral teeth that had been scheduled for removal under GA. When a single episode of pericoronitis was excluded as a valid indication, 39 teeth did not meet criteria for removal but had been scheduled for surgery. It was concluded that two-thirds of lower third molars not meeting NIH consensus criteria for surgery had been scheduled for removal. The reasons for this, which may include inappropriate criteria, require further research.

Adolescent↗

PubMed2006

A comparison of methods for predicting the size of unerupted permanent canines and premolars.

The aim of this study was to examine the reliability of eight methods for determining the mesio-distal crown diameters (MDD) of the permanent canines and premolars (C, P(1), and P(2)). The study models of 120 children (60 boys and 60 girls) aged from 14 to 18 years treated in orthodontic clinics were measured using Seipel's method, with callipers accurate to 0.01 mm. The correlation coefficients were determined between the MDD of C, P(1), and P(2) measured on the study models and the sums calculated using various other methods. The correlation coefficients derived by comparison with the methods of Moyers, Tanka and Johnston, Droschl et al., Legović and Hauz, and Berendonk-Nawrath showed a tendency to over-estimate the MDD of C, P(1), and P(2), while the regression methods of Gross and Hasund, Bachmann, and Tränkmann et al. under-estimated the values. Bachmann's method appeared to give the most reliable results.

Adolescent↗

PubMed2003

Regression equations for determining mesiodistal crown diameters of canines and premolars.

In this study, regression equations (prediction equations) were established for the purpose of accurately predicting the widths of the crowns of unerupted canines (C) and premolars (P1 and P2) on the basis of the measured mesiodistal diameter (MDD) and vestibulooral diameter (VOD) of the crowns of the erupted central and lateral incisors (I1, I2) and first permanent molars (M1). On the plaster casts of 120 subjects (60 boys and 60 girls), MDD and VOD of the crowns of I1, I2, C, both P1 and P2, and M1 on both sides in both jaws were measured twice, with a time distance between measurements. Gradual regression equations were derived on the basis of the measurement results, by which the sums of the widths of crowns of C, P1, and P2 can be predicted using three to five predictors. The coefficients of multiple correlations regarding the sex and the jaw varied from 0.79 to 0.85.

Adolescent↗

PubMed1998

Accuracy of radiographic detection of residual caries in connection with tunnel restorations.

The aim of this study was to evaluate the diagnostic accuracy of radiographic examination for the detection of residual caries after tunnel preparation and filling with glass ionomer cement. Further, two different radiographic modalities were compared. Forty-five extracted human premolars and molars with clinical signs of approximal caries were selected for the study. The teeth were radiographed in order to identify surfaces with dentinal lesions suitable for tunnel preparation. Seventeen of the teeth had lesions that were as a minimum through the enamel and as a maximum into the outer half of the dentin (14 teeth = 1 lesion, 3 teeth = 2 lesions). Seventeen surgically removed third molars were thereafter included. These teeth were sound with respect to caries. The teeth were arranged in blocks with approximal contacts and radiographed using two image receptors: Ektaspeed Plus film (E) and the Digora (D) digital storage phosphor plate system. The 20 carious surfaces and 20 surfaces of the impacted teeth were prepared following the guidelines for the class II tunnel technique and filled with glass ionomer cement. The radiographic examination was repeated with both modalities after filling, and the approximal surfaces scored on the radiographs by 5 observers using the criteria: 0 = no filling, 1 = filling with residual caries, 2 = filling with no adjacent caries. All teeth except the unerupted third molars were sectioned, and the sections examined under the microscope. Residual caries was observed in 8 surfaces. On average, sensitivity was 0.25 for E and 0.32 for D, specificity 0.83 for E and 0.76 for D, positive predictive value 0.38 for E and 0.32 for D, and negative predictive value 0.75 for E and 0.77 for D. The differences between the two modalities were not statistically significant (p > 0.3). Based on the relatively small number of lesions in this study, it is suggested that radiography immediately after tunnel restoration cannot be recommended, as the diagnostic benefit from this examination seems to be minuscule.

Bicuspid↗

PubMed1979

Prediction of lower canine and premolar widths in the mixed dentition.

The purpose of this investigation was to determine whether, with multiple regression analysis, a more accurate method than is now available for predicting the widths of unerupted mandibular canines and premolars of mixed-dentition patients could be developed. Regression analyses were performed on data derived from 83 Caucasian subjects (42 males and 41 females) who participated in the Iowa Growth Study. Measurements were taken on plaster casts of the mandibular incisors, canines, premolars, and first molars. Measurements of the mandibular canines, premolars, and first molars were obtained from periapical radiographs taken with a long-cone technique. Newly developed regression equations for each sex had the highest correlation coefficients and smallest absolute errors of estimate when compared to previously published methods. The new equations and previous prediction methods were tested on a sample of 55 orthodontic patients (23 males and 32 females). The newly developed equations were also the most accurate method of prediction in the orthodontic patient sample.

Adolescent↗

PubMed2005

A treatment difficulty index for unerupted maxillary canines.

The aim of this study was to produce a treatment difficulty index (TDI) for unerupted maxillary canines. Thirty treated cases, each with an unerupted unilateral maxillary canine, were graded by 14 consultant orthodontists in terms of perceived alignment difficulty, and the four main factors which had contributed to each grade were listed in order of importance. The relationship between the grade and the contributory factors was then examined using regression analysis, and weightings were derived. These were applied to each factor, in order to derive a difficulty score total for each case. Linear regression analysis of difficulty scores against consultant grades produced an R2 value of 54.7 per cent using the original equation and an R2 of 52.3 per cent using values rounded to the nearest half. Both indicated a moderate level of agreement between allocated difficulty grade and calculated difficulty scores. The index provides a useful treatment planning aid for the management of impacted maxillary canines.

Adolescent↗

PubMed2005

Prediction of lower permanent canine and premolars width by correlation methods.

The aim of this study was to determine linear regression equations to estimate the widths of unerupted lower permanent canines and premolars using measurements obtained from 45 degrees oblique teleradiographs. The sample consisted of 30 white Caucasian patients orthodontically treated at the Faculty of Dentistry, Universidade Federal do Rio de Janeiro. The records for each patient included a 45 degrees oblique teleradiograph (left side) in the mixed dentition period and a dental cast of the permanent dentition. Pearson's test was applied between each lower canine, first and second premolars measured on the radiograph, and the sum of their actual widths measured on the dental cast. The strongest correlation occurred for the first premolars for one side (.82) and both sides (.84). One linear regression equation was determined to estimate the widths of un-erupted lower canine and premolars of both sides from a single measurement of the first premolar.

Bicuspid↗

PubMed1976

Dental phosphoprotein-induced formation of hydroxylapatite during in vitro synthesis of amorphous calcium phosphate.

(Ethylenedinitrilo)tetraacetic acid soluble phosphoproteins were isolated from rat incisor and bovine unerupted teeth. This material was examined for its effect on the stability of amorphous calcium phosphate in vitro. When the precipitation of amorphous calcium phosphate was attempted in the presence of small amounts of these phospho-proteins, an apatite-like mineral was observed to form, which was approximately 60% crystalline, as determined by infrared measurements. This apatite phase could not be induced by addition of phosphoprotein after the precipitation reaction. The organic phosphate bound to these phosphoproteins was shown to be directly responsible for the formation of the apatite phase, since removal of 60% of the covalently bound phosphate with alkaline phosphatase destroyed the protein's ability to induce hydroxylapatite formation. The properties of the dental phosphoproteins appear to be consistent with their possible involvement in the development of the mineral phase of dentine.

Amino Acids↗

PubMed1996

Hardness and Young's modulus of human peritubular and intertubular dentine.

A specially modified atomic-force microscope was used to measure the hardness of fully hydrated peritubular and intertubular dentine at two locations within unerupted human third molars: within 1 mm of the dentine enamel junction and within 1 mm of the pulp. The hardness of fully hydrated peritubular dentine was independent of location, and ranged from 2.23 to 2.54 GPa. The hardness of fully hydrated intertubular dentine did depend upon location, and was significantly greater near the dentine enamel junction (values ranged from 0.49 to 0.52 GPa) than near the pulp (0.12-0.18 GPa). A Nanoindenter was used to estimate the Young's modulus of dehydrated peritubular and intertubular dentine from the unloading portion of the load displacement curve. The modulus values averaged 29.8 GPa for the peritubular dentine (considered to be a lower limit), and ranged from 17.7 to 21.1 GPa for the intertubular dentine, with the lower values obtained for dentine near the pulp.

Analysis of Variance↗

PubMed1983

Bovine dentin phosphophoryn: composition and molecular weight.

The molecular weight of phosphophoryn, an acidic phosphoprotein unique to dentin matrix, has been difficult to determine because of a combination of neutral protease activities in this tissue and the intrinsic high charge density of the molecule. In this study, bovine dentin phosphophoryn (BDPP) was isolated by a procedure designed to prevent proteolysis. Bovine unerupted third molar powder was demineralized by ethylenediaminetetraacetic acid (EDTA). The EDTA-soluble phosphophoryn fraction was isolated and purified by sequential calcium chloride precipitation, gel filtration in sodium dodecyl sulfate (NaDodSO4) containing buffer, anion-exchange chromatography, and finally gel filtration in 4 M guanidine hydrochloride (4 M Gdn.HCl) buffer. Sedimentation equilibrium, sedimentation velocity, and diffusion coefficient data, viscosity studies in a high ionic strength buffer, and NaDodSO4 gradient gel electrophoresis data gave consistent results for the molecular weight of BDPP, all being in the range of 151 000-167 000. This range is much higher than any previously reported value. An anomalous behavior was observed in nongradient NaDodSO4 gel electrophoresis. Dissociative analytical gel filtration chromatography in 4 M Gdn.HCl gave a molecular weight value of 100 000. This discrepancy was resolved by studying the viscosity of BDPP in 4 M Gdn.HCl which showed BDPP does not assume a true random-chain conformation in this solvent.

Amino Acids↗

PubMed2002

Clinical-statistic survey regarding odontogenic keratocysts in a sample of population in Eastern Sicily.

BACKGROUND: The aim of this study is to point out the frequency, histologically documented, of the odontogenic keratocysts in Eastern Sicily, through the study of a sample of 220 cystic neoformations. Of these, those presenting histopathological peculiarities of odontogenic keratocysts have been examined. METHODS: Fifteen keratocysts were histologically classified. The following characteristics were examined: histological character, age and sex, location of the lesion, association to unerupted teeth. RESULTS: Of the 220 cystic neoformations observed, at the histological examination, 15 were odontogenic keratocysts. The 53% were found in males, against the 47% in females. In the 67% of the cases the lesion involved lower-jaw, against the 33% of the jaw-bone. The greatest frequency was found in the angle of the mandible, followed by the frontal region of the jaw-bone, by the premolar/molar region of the mandible, by the lower frontal region and by the premolar/molar region of the jaw-bone. None odontogenic keratocysts relapsed following surgical operations. Patients are kept under observation and, to this point, elements of release have not emerged. CONCLUSIONS: The epidemiologic data found, are in line with those of the literature. We confirm the necessity of a precocious diagnosis for programming a correct surgical treatment and for reducing the risk of relapse and of ameloblastomatouses transformation.

Adult↗

PubMed2000

'Killer' canines: the morbidity and mortality of ebino in northern Uganda.

In northern Uganda, unerupted primary canine teeth are commonly extracted because they are believed to cause diarrhoea, vomiting, and fever. This practice, known as ebino, is performed under very crude conditions often using unclean tools. To evaluate the morbidity and mortality of complications related to ebino, we retrospectively analysed discharge records from the paediatric ward of Lacor Hospital, Gulu. In the period 1992-98, ebino-related complications, mainly sepsis and anaemia, were among the leading causes of admission (n = 740) and hospital death (n = 156, case fatality rate = 21.1%, proportional mortality rate = 3.3%). Discouraging the adoption of deeply rooted traditional practices that are potentially hazardous to health should be a public health priority in northern Uganda. This could be done by educating not only the general public, but also traditional healers and community and religious leaders, who could convey the knowledge to their people.

Anemia↗

PubMed2001

Microhardness of enamel restored with fluoride and non-fluoride releasing dental materials.

Demineralization caused by frequent ion loss can be detected by a decrease in enamel microhardness. The purpose of this study was to determine the microhardness of the enamel adjacent to restorations with fluoride and non-fluoride dental materials after demineralization and remineralization treatments using crowns of 6 recently extracted unerupted third molars which were sectioned into 4 parts. Five penetrations were made in the enamel of the control group and in the enamel adjacent to restorations made with Vitremer, Heliomolar or Z100, to obtain the Knoop microhardness. There was no significant statistical difference between the microhardness of the enamel of the control group and the enamel adjacent to the restorations made with Vitremer and Heliomolar (p < 0.01), nor between the enamel adjacent to the Heliomolar and Z100 restorations. However, there was a statistically significant difference when the Z100 group was compared to the control group and to the Vitremer group. The results point out that some phenomena occurred which interferred with the ionic loss and, consequently, the microhardness of the enamel of the Vitremer and Heliomolar groups, because it was not possible to observe any difference between the microhardness of the enamel of the control group and the groups restored with Vitremer and Heliomolar.

Acrylic Resins↗

PubMed1991

Assessing the eruption of lower third molars on the basis of radiographic features.

To determine radiographic features by which one could estimate whether lower third molars are likely to erupt after the age of 20 years, university students with a total of 84 unerupted or partially erupted lower third molars were followed up. Five radiographic features of each third molar were measured from the panoramic tomogram taken at age 20 years, and the status of third molars was examined for a second time at age 26 years. The results showed that the lower third molars that did erupt after the age of 20 years were initially: 1) root formation complete; 2) impacted in soft tissue; 3) vertical; 4) placed at the same occlusal level as the neighbouring second molar; 5) showed sufficient space between the ramus and the second molar. In contrast, the teeth that remained impacted at the age of 26 years showed such initial features as: 1) incomplete root formation; 2) embedding in bone; 3) mesioangularity; 4) situated at the cervical level of the neighbouring second molar. It was concluded that a panoramic tomogram taken at age 20 years revealed radiographic features on which an estimation of future eruption of mandibular third molars could be based.

Adult↗

PubMed1996

Immunohistochemical localization of HLA-DR-positive cells in unerupted and erupted normal and carious human teeth.

Class II major histocompatibility complex (MHC) antigen-expressing cells are generally associated with the early phase of the immune response. We have studied the distribution of class II-expressing cells in developing, normal, and carious human teeth to clarify when human pulp acquires an immunologic defense potential and how this reacts to dental caries. Antigen-expressing cells were identified immunohistochemically by means of HLA-DR monoclonal antibody. In the pulp of unerupted developing teeth, numerous HLA-DR-positive cells were distributed mainly in and around the odontoblast layer. In erupted teeth, HLA-DR-positive cells were located, for the most part, just beneath the odontoblast layer, with slender cytoplasmic processes extending into the layer. Superficial caries lesions caused an aggregation of HLA-DR-positive cells in dental pulp corresponding to the lesion. In teeth with deeper caries lesions, this aggregation of cells expanded to include the odontoblast layer. Also noted were HLA-DR-positive cells lying along the pulp-dentin border, with cytoplasmic processes projecting deep into the dentinal tubules, where they co-localized with odontoblast processes. These findings suggest that: (1) human dental pulp is equipped with immunologic defense potential prior to eruption; (2) in the initial stage of caries infection, an immunoresponse mediated by class-II-expressing cells is initiated in human dental pulp; and (3) HLA-DR-positive cells trespass deep into dentinal tubules as the caries lesion advances.

Adolescent↗