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PubMed2004

Conservative endodontic treatment of teeth fractured in the middle or apical part of the root.

According to treatment type, root-fractured teeth with pulp necrosis or exposed pulps were divided into five groups, group 1: 17 teeth in which the root canal of the coronal fragment only was filled with gutta-percha (GP); group 2: seven teeth in which the root canals of the coronal and apical fragments were both filled with GP; group 3: 19 teeth in which the coronal fragment was filled with GP and the apical fragment was surgically removed; group 4: 68 teeth where the root canal of the coronal fragment was treated with calcium hydroxide and subsequently filled with GP; and group 5: five vital teeth with root and concomitant crown fractures in which the exposed pulps were treated by partial pulpotomy. The frequency of periodontal healing was 76% in group 1, zero in group 2, 68% in group 3 and 86% in group 4. Compared with groups 1 and 2 combined, healing in group 4 was significantly more frequent. In groups 1, 2 and 4, failures occurred significantly more often in teeth showing overfilling, i.e. protrusion of GP into the space between the fragments, compared with teeth without overfilling. All five teeth in group 5 showed healing. It was concluded that root canal filling with GP of the coronal fragment only, with or without surgical removal of the apical fragment, can be successful in selected cases. Treatment of the root canal with calcium hydroxide followed by GP filling appears to be the treatment of choice in root-fractured non-vital teeth. Partial pulpotomy of exposed pulps in five teeth showed results similar to root-unfractured teeth with pulp exposure treated with this technique.

Adolescent↗
PubMed2003

Radiographic findings on 3rd molars removed in 20-year-old men.

In this study we assess radiographic findings characteristic of mandibular 3rd molars that had required either routine or surgical extraction. X-ray findings relating to acute pericoronitis were also examined. The material was collected by investigating patient records and rotational panoramic radiographs of 20-year-old Finnish male conscripts (n = 738) treated during military service because of 3rd-molar-related problems. The follicle around the crown of mandibular 3rd molars with acute pericoronitis was enlarged in 19% of cases and in 13% of chronic symptom-free pericoronitis cases (not statistically significant difference). Mandibular 3rd molars extracted surgically were more often mesially inclined than those extracted routinely (61% vs. 23%; P < 0.001), partially or totally intrabony impacted (92% vs. 66%; P < 0.001) and deep situated (on average 4.2 mm vs. 2.5 mm under the occlusal plane). Surgical extraction was also associated with the roots completely developed [92% vs. 84% of the teeth routinely extracted, odds ratio (OR) 2.6, 95% confidence interval (CI) 1.2-5.5] and with the absence of radiographic pericoronitis [around 27% vs. 39% of the teeth routinely extracted (OR 0.5, 95% CI 0.3-0.8)]. In 86% of cases the space between 2nd molar and ramus of the mandible was narrower than the 3rd molar extracted surgically, whereas this was 62% in routine extraction cases (P < 0.001). We conclude that there are some typical 3rd-molar findings in rotational panoramic radiographs that show a need for surgical extraction.

Adult↗
PubMed1997

Phosphor-stimulated computed cephalometry: reliability of landmark identification.

The aim of this randomized, controlled, prospective study was to determine the reliability of computed lateral cephalometry (Fuji Medical Systems, Tokyo, Japan) in terms of landmark identification compared to conventional lateral cephalometry (CAWO, Schrobenhausen, Germany). To assess the reliability of landmark identification on lateral cephalographs, 20 computed images, taken at 30 per cent reduced radiation (70 kV, 15 mA, 0.35 s) were compared to 20 conventional images (70 kV, 15 mA, 0.5 s). The 40 lateral cephalographs were taken from 20 orthodontic patients at immediate post-treatment and 1 year after retention. The order and type of imaging was randomized. Five orthodontists identified eight skeletal, four dental and five soft tissue landmarks on each of the 40 films. The error of identification was analysed in the XY Cartesian co-ordinate following digitization. Skeletal landmarks exhibited characteristic dispersion with respect to the Cartesian co-ordinates. Root apices were more variable than crown tips. Soft tissue landmarks were more consistent in the X co-ordinate. Two-way ANOVA shows that there is no significant difference between the two imaging systems in both co-ordinates (P > 0.05). Moreover, the differences are generally small (< 0.5 mm), and are unlikely to be of clinical significance. Most of the variables attained statistical power of at least 0.8 in the X-co-ordinate while only the dental landmarks achieved statistical power of at least 0.78 in the Y-co-ordinate. Based on the results of the study: (1) computed lateral cephalographs can be taken at 30 per cent radiation reduction, compared to conventional lateral cephalograph; (2) each anatomical landmark exhibits its characteristic dispersion of error in both the Cartesian co-ordinates; (3) there is no trend between the two imaging systems, with equivocal result, and none of the landmarks attained statistical significance when both raters and imaging systems are considered as factorial variables; (4) the random error of raters in landmark identification after replicate tracing was highlighted and needs to be taken into consideration in all studies involving landmark identification.

Adolescent↗
PubMed2000

Effects of prism orientation on tensile strength of enamel.

PURPOSE: This study tested the hypothesis that the tensile strength of enamel varies according to prismatic orientation. MATERIALS AND METHODS: Eight extracted, caries-free human third molars were thoroughly cleaned with pumice and water. The entire enamel surface was conditioned with 37% phosphoric acid for 30 s, air dried, and bonded with Single Bond adhesive system. Several layers of composite (Z-100) were incrementally applied to the crown to build up a "cube-like" resin structure approximately 5 mm thick covering the entire crown of the teeth. The teeth were stored for 24 h in water at 37 degrees C, and then the crown was serially, vertically sectioned in a mesio-distal direction to obtain several slices approximately 0.7 mm thick. The slices were sectioned into halves, and each half was gently trimmed from both sides with a diamond bur to reduce the cross-sectional area to a "neck" located in enamel, either on the external slope or functional slope of the cusps. The specimens were trimmed to permit testing of enamel with its prisms either oriented parallel (PL) or perpendicular (PD) to the applied load. The trimmed specimens were glued to the fixtures of a Vitrodyne tester and stressed in tension at 0.5 mm/min. SEM images were taken from the fractured surfaces to examine the site of failure and confirm the prism orientation. RESULTS: Mean tensile strength of enamel was 24.7 +/- 9.6 MPa (n = 22) for PL and 11.4 +/- 6.3 MPa (n = 22) for PD oriented enamel prisms (t value = -5.45, p < 0.05). There was no significant difference between specimens originating from different slopes of the cusps (p > 0.05). CONCLUSION: The results showed that tensile strength of enamel is dependent on the prismatic orientation.

Acid Etching, Dental↗
PubMed2002

Asymmetrical morphogenesis and medio-lateral positioning of molars during mouse development.

The functionality of the dentition depends on occlusal relationships between opposing crown surfaces. To investigate the relative changes in positioning of upper and lower molar germs during mouse development, we used serial histological sections of late day 13 (embryonic day (ED)13.5) to early day 18 (ED18) foetus heads and performed computer-aided 3D reconstructions. From ED13.5 to ED15.5. the first lower molar (M1) got a less medial position relative to its upper counterpart (M1); superimposition progressed postero-anteriorly. From ED14.5, the apparent medial displacement of M(1) vs. M1 was partly due to the asymmetrical growth of the M(1) to give rise to the lingual row of cusps, conspicuous at ED17. The superimposition of M(2)/M2 along the medio-lateral axis was observed from their bud stage (ED14.5), and the one of M(1)/M1 was almost complete at ED15.5. However, this was not the final position. as at ED 18, M1 and M2 had a more lateral location than their upper counterparts. Immunostaining showed that differential expression of antigens associated to desmosomes but not to adherens junctions might be involved in the asymmetrical development of M(1) thus contributing to the relative medio-lateral positioning of the first molars at early stages.

Adherens Junctions↗
PubMed1997

Characteristic high- and low-frequency dental traits in sub-Saharan African populations.

In an earlier investigation (Irish [1993] Biological Affinities of Late Pleistocene Through Modern African Aboriginal Populations: The Dental Evidence [Ann Arbor: University Microfilms]), biological affinities of 32 sub-Saharan and North African dental samples were estimated using comparative analyses of 36 dental morphological traits. Marked dental homogeneity was revealed among samples within each of the two geographic regions, but significant interregional differences were noted. Assuming dental phenetic expression approximates or is an estimate of genetic variation, the present study of 976 sub-Saharan-affiliated Africans indicates they are not closely related to other world groups; they are characterized by numerous morphologically complex crown and root traits. Turner ([1984] Acta Anthropogenetica 8:23-78; [1985] in R Kirk and E Szathmary (eds.): Out of Asia: Peopling the Americas and the Pacific [Canberra: The Journal of Pacific History], pp. 31-78; [1990] Am. J. Phys. Anthropol. 82:295-318; [1992] Persp. Hum. Biol. 2/Archaeol. Oceania 27:120-127; [1992] in T Akaszawa, K Aoki, and T Kimura (eds.): The Evolution and Dispersal of Modern Humans in Asia [Tokyo: Hokusen-Sha Publishing Co-], pp. 415-438) reports that Northeast Asian/New World sinodonts also have complex teeth relative to Europeans, Southeast Asian sundadonts, Australian/Tasmanians, and Melanesians. However, sinodonty is characterized by UI1 winging, UI1 shoveling, UI1 double shoveling, one-rooted UP1, UM1 enamel extension, M3 agenesis, and three-rooted LM1. Sub-Saharan peoples exhibit very low frequencies of these features. It is proposed that the collection of dental traits which best differentiate sub-Saharan Africans from other worldwide samples includes high frequencies of the Bushman Canine, two-rooted UP1, UM1 Carabelli's trait, three-rooted UM2, LM2 Y-groove pattern, LM1 cusp 7, LP1 Tome's root, two-rooted LM2, UM3 presence, and very low incidences of UI1 double shoveling and UM1 enamel extension. This suite of diagnostic traits is termed the sub-Saharan African dental complex.

Africa South of the Sahara↗
PubMed2004

Type of treatment, prognosis, and estimation of time spent to manage dental trauma in late presentation cases at a dental teaching hospital: a longitudinal and retrospective study.

Traumatic dental injuries are emergencies that must be treated promptly and properly in order to reduce the suffering, costs, and time for patients, parents, and health care providers. The aim of this study was to investigate the treatment, long-term prognosis, and number of visits needed to manage cases resulting from complications of late presentation of traumatic dental injuries. The sample consisted of 195 children, all presented with complications of dental trauma at the Pediatric Dentistry Clinics in the Dental Teaching Hospital of Jordan University of Science and Technology in Irbid city, Jordan. Retrospective data relied on trauma forms as well the clinical notes and radiographs in the patients' records. Prospective data was collected by examining patients at recall appointments. The treatment of traumatized teeth in this sample ranged from no active treatment to extraction and prosthetic replacement. It was estimated that the number of visits needed to carry out the planned treatment for these patients ranged between 3 and 17.2 visits according to the type of treatment. Apexification procedure was the most time consuming. Thirty-two per cent of teeth with apexification ended up with root fracture mainly subsequent to another minor trauma episode (in 85%), the rest were reported to be spontaneous fractures. Almost half of the teeth with luxation injuries became necrotic after 3 years. Teeth with avulsion actually kept on deteriorating even at the 36-month follow-up appointment. The long-term prognosis of teeth with middle root fracture was favorable in (80%) of the teeth in the sample, despite the fact that they were splinted late. Luxation injuries led to more necrotic teeth (50%) than uncomplicated crown fractures. Multiple dental trauma episodes (MDTE) were reported in about 30% of the patients in the sample and were responsible for some of the complications noticed in this report. As all cases followed up in this report are late presentation of dental trauma, the findings may emphasize and highlight predictors for healing and favorable long-term prognosis for such injuries. This will help selecting the treatment option that would lead to better outcomes with less expense and less time consumption for dentists and patients alike. The findings of this report also stress the importance of prevention of dental trauma and minimize its complications through proper treatment, educational programs, supervision of children during play, use of mouth guards, and orthodontic treatment of proclined incisors.

Child↗
PubMed2006

Compressive strength recovery by composite onlays in primary teeth. Substrate treatment and luting agent effects.

OBJECTIVES: To evaluate 1% NaOCl treatment and two resin luting agent effects on compressive strength recovery in composite onlays on primary teeth and to analyze the fractures type. METHODS: Forty sound primary molars crowns were prepared in the standard machine and randomly divided into four groups (n=10): G1 (1% NaOCl/ 30 min+EnForce); G2 (without 1% NaOCl EnForce); G3 (1% NaOCl/ 30 min+Rely X); G4 (without 1% NaOCl+Rely X). The onlays were made using Z250 composite on plaster models. Ten sound teeth were used as control group (CG). All groups were submitted to compression mechanic test in a universal test machine INSTRON at 1mm/min cross-head speed. After that, the data (kgf) were submitted to ANOVA test (alpha=0.05). Finally, the fracture types were classified in a crescent scale (1-5) related with severity degree and submitted to Fisher's Exact Test (p<0.05). Scanning electronic microscope analysis was done in order to illustrate the fractures sites. RESULTS: The values of compressive strength of experimental groups did not differ each others neither from control group (p>0.05). The results from fracture type showed that types 5 and 4 fractures (most severe) present the highest percentage to experimental groups. Conversely, the CG showed higher percentage of fracture types 2 and 3. CONCLUSIONS: This research found that the composite onlays recovered the compressive strength compared to sound teeth, regardless of the substrate treatment and cement agent used. Nevertheless, no group showed similar type of fractures to CG, which had more frequency of less severe fracture types.

Acetone↗
PubMed2001

Root trunk concavities as a risk factor for regenerative procedures of class II furcation lesions in dogs.

BACKGROUND: The purpose of this study was to evaluate the influence of root trunk concavities on guided tissue regeneration. METHODS: The second, third, and fourth mandibular bicuspids of 4 healthy mongrel dogs were used. Full flaps were elevated and furcation lesions (5 mm in height and 2 mm in depth) were surgically created. One mm deep concavities were prepared on the root trunks and part of the crown of all teeth. The second bicuspids remained as controls (C); the left third and fourth bicuspids received normal expanded polytetrafluoroethylene (ePTFE) membranes (NM) and the right bicuspids received modified ePTFE membranes (MM). The MM were made by removing the collar from an NM, cutting it into 2 mm segments, and suturing each of the segments to the collar of each MM. Normal and modified membranes were sutured to their corresponding teeth and the flaps sutured. After the healing period, the mandibles were removed and the teeth processed for histomorphometry. RESULTS: The results showed that the junctional epithelium measured a mean of 0.71 mm for C, 0.64 mm for NM, and 0.14 mm for MM. The differences between C and MM and between NM and MM were both statistically significant at the 5% level (Kruskal-Wallis test). Mean bone height measurements for the buccal surfaces from the furcation roofs were 2.79 mm for C, 2.60 mm for NM, and 1.06 mm for MM and for the mid-portion 1.10 mm for C, 1.23 mm for NM, and 0.30 mm for MM. Differences were statistically significant at the 1% level between C and MM and between NM and MM for the buccal measurements, and at the 5% level between NM and MM for the mid-portion measurements. CONCLUSIONS: Root trunk concavities are important risk factors for regenerative procedures. The collars of the membranes should be modified to improve results when concavities are present.

Alveolar Process↗
PubMed2007

Effects of water fluoride exposure at crown completion and maturation on caries of permanent first molars.

Pre-eruptive fluoride exposure has been shown to be important for caries prevention. This paper aimed to determine the relative effects of water fluoride exposure during crown completion (CC) and maturation on caries experience in first permanent molars. Parental questionnaires covering residential history were linked to oral examinations of 19,885 6- to 15-year-old Australian children conducted in 1992 by the School Dental Services of South Australia and Queensland. The percentage of lifetime exposed to optimally fluoridated water at CC, maturation (MAT) and post-eruption (POST) was calculated. Combined exposure variables describing different levels of CC, maturation and post-eruption were created using a threshold exposure of 50%. Compared to the reference of CC <50%/MAT <50%/POST <50%, the categories CC > or =50%/MAT <50%/POST > or =50% [rate ratio (RR) 0.52], CC > or =50%/MAT > or =50%/POST <50% (RR 0.61) and CC > or =50%/MAT > or =50%/POST > or =50% (RR 0.67) had the strongest caries-preventive effect, followed by CC > or =50%/MAT <50%/POST <50% (RR = 0.79) and CC <50%/MAT > or =50%/POST > or =50% (RR = 0.81) in negative binomial regression models (p < 0.05). The categories CC <50%/MAT > or =50%/POST <50% (RR = 0.85) and CC <50%/MAT <50%/POST > or =50% (RR = 0.84) had weaker, non-significant caries-preventive effects. In conclusion a high exposure at CC was important for caries prevention irrespective of the effect of exposure at maturation and post-eruption. The strongest caries-preventive effect was produced by a high exposure at CC supplemented by a high exposure at maturation and/or post-eruption, but the latter two phases could not produce a significant caries-preventive effect on their own. Since most of the caries occurred on pit and fissure surfaces, the findings relate to this class of lesion.

Adolescent↗
PubMed2000

Localised enamel hypoplasia of human deciduous canines: genotype or environment?

A discrete area of defective enamel formation that appears on the labial surface of the crowns of deciduous canine teeth has been described in both recent and prehistoric human populations, with reported frequencies varying from 1 to 45 per cent. Suggestions about the aetiology of this localized hypoplasia range from genotypic factors to environmental conditions and systemic effects. The major aims of this study were to describe the frequency of occurrence and pattern of expression of the lesion in Australian Aboriginal and Caucasian ethnic groups, and to clarify the role of genetic factors by examining a sample of twins. The study sample consisted of dental casts of 181 pairs of Australian Caucasian twins, 215 Aborigines and 122 Caucasian singletons, together with 253 extracted deciduous canines. Examination of dental casts and extracted teeth was undertaken under 2x magnification with emphasis being placed upon location and expression of the lesion. The defect was observed in 49 per cent of twins and 44 per cent of Aborigines, but only 36 per cent of singletons. The percentages of affected teeth in each group were: 18 per cent in twins, 17 per cent in Aborigines and 13 per cent in Caucasians. A significant proportion of the defects occurred on the mesial aspect of the labial surface, in the middle area incisocervically, with the majority in the lower jaw. A number of significant differences in frequency were observed between groups, sexes, arches and sides. The results confirm some of the findings of previous studies, but also suggest that none of environmental, genetic or systemic factors can be ruled out as being involved in aetiology of the defect. The higher incidence of the lesion occurring on the mesial aspect of the labial surface is suggestive of physical trauma. Also, the vulnerability of the prominent developing mandibular canine, with its thin or missing labial covering of bone, would be expected to lead to higher prevalence of the lesion in the lower jaw. Although not definitive, the results of concordance analyses in twins were suggestive of a possible genetic predisposition in the formation of the lesion. Further research with a greater clinical orientation and emphasis on determining specific aetiological factors within any given environment in different ethnic groups may provide better insight into the ambiguous aetiology of the hypoplastic enamel defect.

Australia↗