Classification of dental caries patterns in the primary dentition: a multidimensional scaling analysis

OBJECTIVE

Clinical patterns of early childhood caries (ECC) encompassing specific teeth or surfaces have been previously proposed on an a priori basis and have been used as case definitions. The underlying assumption is that the patterns result from different host response and environmental conditions. Identifying caries patterns has utility in refining case definitions of ECC. Well-defined caries patterns should enhance the ability of an analysis to identify meaningful associations between suspected risk factors and ECC. The purpose of this project was to identify patterns of caries in the dentition of preschool children using multidimensional scaling without a priori pattern delineation.

METHODS

Between February 1994 and September 1995, five examiners visually examined 5171 Arizona preschool children aged 5-59 months old. Multidimensional scaling (MDS) was used as a classification/taxonomy technique to identify any underlying structure of the caries data. MDS provided a classification scheme for individual tooth surfaces based on the dissimilarity measures of squared Euclidean distance and of variance using an alscal analysis. Both two- and three-dimensional solutions were pursued; s-stress, stress, R-square and residual patterns were assessed in determining the best dimensional model, with the resulting quadrant positions of the tooth surfaces suggesting potential caries patterns.

RESULTS

All models demonstrated excellent fit. Two- and three-dimensional solutions suggested four caries patterns: (i) any maxillary incisor surfaces, (ii) first molar occlusal surfaces, (iii) second molar pit and fissure surfaces, and (iv) any smooth surfaces, excluding the maxillary incisor surfaces.

CONCLUSIONS

This is the first delineation of primary dentition caries patterns produced by a classification analysis without a priori pattern definitions. The identified caries patterns may arise from specific risk factors and/or be a function of the timing of various risk factor exposures. Use of these patterns as case definitions should enhance the ability to identify associations between suspected risk factors and ECC.

Bond failure and decalcification: A comparison of a cyanoacrylate and a composite resin bonding system in vivo

This prospective, in vivo study compared bond failure and enamel decalcification with a cyanoacrylate bracket bonding system (SmartBond, Gestenco International, Gothenburg, Sweden) and a traditional light-cured composite system (Light Bond, Reliance Orthodontic Products, Itasca, Ill). A total of 327 teeth were evaluated after a period of 12 to 14 months; 163 experimental teeth were bonded with the cyanoacrylate bonding system, and 164 control teeth were bonded with the light-cured composite resin. All teeth were evaluated for breakage (bond failure). The average percentage of bracket failures with cyanoacrylate was 55.6% compared with 11.3% with composite resin (P <.001). All maxillary anterior teeth (94) were evaluated for enamel decalcification on a graded scale. Occurrence of enamel decalcification between the 2 bonding systems after 1 year of orthodontic treatment was similar. The cyanoacrylate bonding material had more than 4 times as many bond failures and a similar amount of decalcification as the traditional composite material. Cyanoacrylate as a routine orthodontic bonding agent is not a suitable bonding material for clinical practice at this time. It is important to test new bonding systems in vivo in several studies before using them in routine clinical practice.

Technical quality of root canal treatment in Taiwan

AIM

To evaluate the current technical quality of root canal treatment (RCT) in Taiwan.

METHODOLOGY

A total of 1085 RCT cases, randomly selected from a large sample and representative of the Taiwanese population from April to September 2000, were evaluated by eight endodontic specialists. The qualitative evaluation of RCT cases was based on two variables: length of the root filling and density of the obturation. A root canal with both adequate filling length (the apical termination of the root filling within 2 mm of the radiographic apex) and complete obturation (no lateral or apical canal lumen visible in the apical one-third of the root canal) was defined as having good-quality endodontic work (GQEW). A tooth was defined as having a GQEW when all its canals were categorized as GQEW.

RESULTS

From a total of 1867 root canals, overfilling occurred in 235 (12.6%), adequate filling length in 1152 (61.7%), underfilling in 466 (25.0%) and no filling in 12 (0.6%). Of the 1867 root canals, 710 (38.0%) demonstrated complete obturation and 1157 (62%) demonstrated incomplete obturation. GQEW was found in 650 (34.8%) root canals and 329 (30.3%) teeth. The percentage of teeth with GQEW in hospital cases (38.1%) was significantly greater (P < 0.001) than that in private clinic cases (24.3%). In addition, the frequency of teeth with GQEW in the anterior teeth (40.4%) or in the premolars (33%) was significantly greater (P < 0.001) than that in the molars (18.4%).

CONCLUSIONS

Approximately 70% of the teeth receiving RCT in Taiwan were either of inadequate filling length or sealing density.

Comparative evaluation of a new removable Jasper Jumper functional appliance vs an activator-headgear combination

The aim of this study was to comparatively evaluate the effects of an activator-headgear (HG) combination to a Jasper Jumper (JJ) plus occipital HG, which was incorporated into removable upper and lower plates. The study group consisted of 60 subjects with mandibular deficiency and a vertical growth pattern. Of these, 20 were treated with JJ appliance-HG incorporated to removable upper and lower plates, 20 were treated with an activator-HG combination. Another 20 subjects who refused orthodontic treatment served as controls. Pre- and postreatment lateral cephalograms and hand-wrist films were gathered for all 60 subjects. Lateral cephalograms were manually traced before being transferred to RMO JOE software by a digitizer. Measurements that are not included in the software were measured manually. Thirty-five dental and skeletal parameters were used in the study. The collected data were subjected to statistical analysis using SPSS packet software. Wilcoxon paired t-test was used for intragroup comparisons. Differences between groups were evaluated by analysis of variance and Bonferroni tests. Results suggest that ANB angle was decreased significantly in both treatment groups compared with the controls. Increase in total facial height was greater in the activator group than in the JJ group. Vertical growth inhibition of lower incisors was greater in the JJ group. The activator-HG appliance was more effective on the mandible, whereas the JJ appliance was mainly active on the maxilla. Thus, ideal cases for JJ-splinted appliance should be high-angle cases, particularly with maxillary excess and some mandibular deficiency.

Outcome of orthodontic space closure with a missing maxillary central incisor

Orthodontic space closure is one of the treatment alternatives when a maxillary central incisor is missing. Because no systematic analysis of such treatment results is available, a sample of 20 consecutively treated patients was examined in a follow-up study. All patients had received orthodontic treatment with the objective of closing the space for the missing central incisor. Biologic features and the clinical appearance of the recontoured lateral incisor (test tooth) replacing the missing tooth were compared with the neighboring intact central incisor, which served as control tooth. The patients' opinions regarding the treatment and the result were recorded in a questionnaire. The position of the examined teeth and the appearance of the surrounding soft tissues were similar in the test and control teeth. However, in some patients (25%), certain aspects of the recontoured incisor crown (such as the width at the gingival margin) mismatched the appearance of the controls. A somewhat increased mobility and probing pocket depth on the mesial aspect was recorded for some test teeth. No obvious detrimental effects were observed on the radiographs. Most patients expressed satisfaction with the treatment result. It is concluded that orthodontic mesialization of the lateral incisor to replace a missing central incisor is a valid treatment modality, if the indications for such treatment are present and careful attention to detail in orthodontic and restorative treatment is exercised.

Case report: two nasal floor compound odontomas associated with impacted maxillary incisor

AIM

The purpose of this report is to describe the logical sequence of treatment in a case of a six year old caucasian female patient with two nasal floor compound odontomas, that delayed eruption of a maxillary permanent incisor.

TREATMENT

The odontomas were surgically removed. However, as the maxillary incisor did not erupt spontaneously, after a suitable period of observation, an orthodontic treatment approach was adopted. This was to obtain an adequate space for the unerupted tooth and to move it to its normal position.

CONCLUSION

Early diagnosis and surgical intervention of supernumeraries is therefore necessary and treatment of an impacted tooth may require an orthodontic appliance.

Dental crowding in primary dentition and its relationship to arch and crown dimensions

PURPOSE

The purpose of this study was to compare dental arch size, mesiodistal and buccolingual crown widths, and crown shapes between 2 groups of children, 1 with anterior crowding in both dental arches and another with anterior spacing in both dental arches.

METHODS

Sixty-one sets (27 crowded and 34 spaced arches) of dental casts of normal occlusions were examined.

RESULTS

For both lower and upper arches, crowded arches had statistically significantly smaller arch widths than did the spaced arches. The buccolingual width of the upper second primary molar of the crowded arches was statistically significantly larger than that of the spaced arches. However, there were little significant differences between crowded and spaced arches in arch length, mesiodistal crown width, and crown shape.

CONCLUSIONS

It can be concluded that the factor that determines whether a primary dental arch is crowded is the absolute width of the arch.

Orthodontic treatment of a patient with an unusual impaction of a central incisor: case report

This report documented an unusual case with impaction of a right permanent central incisor. The purpose of this work was to illustrate how the original lingual lever arm moved the impacted central incisor in the dental arch. The authors used a modified lingual arch made of .036 inch stainless steel wire soldered to bands on the second primary molars. The lingual arch caused some minor inconveniences, but the discomfort was slight. Patient compliance was not a problem because a fixed appliance was used in the primary dentition.

Diagnosis and management of maxillary incisors affected by incisal wear: an interdisciplinary case report

In the attempt to restore anterior teeth affected by erosion and bruxism, many clinicians have been frustrated with the constant restorative failures. Frequently, these failures are attributed to the restorative materials employed, especially in cases in which composite resins are used. However, some flaws of the restorations are related to the oversight of occlusal principles. The purpose of this article is to discuss the etiology, signs, and symptoms of incisal wear, with special attention to that caused by bruxism and chemical erosion. Relatively simple management techniques (e.g., occlusal adjustment, adhesive restorations) are proposed, and the diagnosis and management of a representative clinical case is presented.

CLINICAL SIGNIFICANCE

In some cases of bruxism and/or dental erosion, it is possible to acquire space to recuperate the esthetics and function of maxillary incisors affected by incisal wear through a conservative treatment associated with the control of the etiologic factors.

Esthetic rehabilitation of anterior teeth affected by enamel hypoplasia: a case report

Alterations during tooth structure formation, mainly on anterior teeth, are known to severely compromise esthetics. This article presents a case report in which the etiology and clinical characteristics of anterior teeth affected by enamel hypoplasia are analyzed. The restoration treatment sequence is also discussed, demonstrating that the use of a hybrid and a microfilled composite associated with tooth hybridization (interdiffusing zone) can be used to conservatively rehabilitate a smile.

CLINICAL SIGNIFICANCE

This article presents a simple and conservative technique for restoring disfiguring areas of enamel hypoplasia to achieve an optimally esthetic result.

Development of enamel defects in rat mandibular incisor after thyro-parathyroidectomy

Previous studies with scanning electron microscopy (SEM) demonstrated the presence of small hypoplastic defects in the incisal third of incisors and deep hypoplasia in the apical third of the incisors after thyro-parathyroidectomy in the rat. These studies provided a morphological description of the defects, but uncertainty remained concerning their development throughout amelogenesis. The aim of the present investigation was to study, with SEM operated in the backscattered mode, the development of the hypoplastic defects, from the beginning of the secretion to the end of the maturation zone of the enamel, in the lower incisor of thyroparathyroidectomized rats. The results of the present study showed that the large and small defects developed are separate entities that do not develop into the other. The distribution of large defects might be linked to a reduction of the eruption rate in these rats. The pathogenesis of these defects needs further investigation.

Perception of dental fluorosis amongst Ethiopian children and their mothers

This study was conducted in three Ethiopian Rift Valley villages known for endemic fluorosis. Three-hundred-and-six adolescents (12-15 years) and 233 mothers participated. The aim was to study dental fluorosis in the youngsters and to assess the extent of agreement between clinical and self-rated discoloration and pitting of teeth, and also the level at which dental fluorosis is perceived as a problem both by children and their mothers. The children (154 M and 152 F) gave a simple self-assessment of tooth-color and quality of their teeth, and were subsequently examined for dental fluorosis. Finally, four color photographs of teeth with dental fluorosis (TF-scores 2, 3, 5, and 7) were used as references during a structured oral interview of the children, as well as their mothers. At TF score > or = 2, the prevalence of dental fluorosis on maxillary central incisors was 72% and 37% at TF score > or = 4. The mean TF score was significantly higher among boys than among girls of unemployed fathers compared to children of employed fathers. The likelihood of reporting problems with dental appearance increased with increasing individual TF scores. The child/mother pairs found teeth with TF scores 2 and 3 esthetically acceptable, while teeth with TF scores 5 and 7 were considered unacceptable. Mothers were more critical of severe fluorosis than were their children.

Some factors associated with open gingival embrasures following orthodontic treatment

Open gingival embrasures or "black triangles" can be an undesirable outcome of adult orthodontic treatment. The aims of the present study were to determine the prevalence of open gingival embrasures in a group of orthodontic patients, and to determine if open gingival embrasures were related to: age at the start of treatment, the severity of pretreatment crowding of the mandibular incisors, the duration of treatment or changes in alveolar bone height. The subjects were 80 orthodontic patients (33 males, 47 females) between 15 and 31 years of age. Open gingival embrasures were found in 43.7 per cent of all subjects, while in subjects over 20 years of age the prevalence was 66.7 per cent. In relation to the amount of crowding 42.8 per cent of the subjects with less than 4 mm crowding had open gingival embrasures, 41.2 per cent of those with between 4 and 8 mm crowding had open gingival embrasures, and 50 per cent of those with more than 8 mm crowding had open gingival embrasures. The groups were not significantly different. Approximately 42 per cent of the subjects in the shorter treatment group had open gingival embrasures, and 44.4 per cent of those whose treatment took longer than 3 years had open gingival embrasures. This difference was not statistically significant. Cephalometric measurements of mandibular alveolar bone height indicate that open gingival embrasures were more likely to be due to resorption of the alveolar crest rather than extrusion of the mandibular incisors. In conclusion, open gingival embrasures were more frequently found in patients over 20 years of age than in younger patients, and were associated with resorption of the alveolar crest.

Reasons for the placement and replacement of crowns in general dental practice

AIMS

The purpose of the study was to apply established methods to survey reasons for the placement and replacement of crowns in general dental practice in the United Kingdom.

MATERIALS AND METHODS

One hundred and twenty-eight general dental practitioners were recruited. Participants recorded the principal reason for the provision of each initial and replacement crown they provided over a 12-week period.

RESULTS

Overall, data were collected from 92 practitioners in respect of 1714 patients and 2164 crowns, of which 1452 (67%) were initial placements and 712 (33%) replacements. The teeth most frequently crowned were maxillary incisors (33%), with 72% of the crowns surveyed being of the porcelain bonded to metal variety. Overall 64% of the initial placement crowns were provided because of restoration failure (26%) or tooth fracture (38%). The most common reason for crown replacement was crown failure (27%).

CONCLUSION

It is concluded that surveys of the type reported may provide new insights into the reasons for and pattern of provision of initial placement and replacement crowns in clinical practice. In this study the most common reason for the provision of initial placement crowns was tooth fracture. The most common reason for the replacement of crowns, notably porcelain jacket crowns, was crown fracture.

Effects of post-core design and ferrule on fracture resistance of endodontically treated maxillary central incisors

STATEMENT OF PROBLEM

Studies concerning the effects of post-core design and ferrule on the fracture resistance of endodontically treated teeth remain controversial.

PURPOSE

The purpose of this study was to investigate in vitro the effects of post-core design and ferrule on the fracture resistance of root canal treated human maxillary central incisors restored with metal ceramic crowns.

MATERIAL AND METHODS

Forty-eight extracted human maxillary central incisors were endodontically treated and divided into 4 groups of 12. The following treatments were evaluated: group A: restored with metal ceramic (porcelain fused to metal [PFM]) crowns as control; group B: 2-mm ferrule/custom cast post-core/PFM crowns; group C: no ferrule/custom cast post-core/PFM crowns; and group D: 2-mm ferrule/prefabricated post and resin core/PFM crowns. Each specimen was subjected to load (N) on the lingual surface at a 135-degree angle to the long axis with a MTS 810 material testing machine until fracture at a crosshead speed of 0.02 cm/min. One-way analysis of variance and nonparametric chi-square test were used to compare the results. A significant analysis of variance result was followed by Newman-Keuls pairwise multiple comparisons (P<.05).

RESULTS

There were significant differences among the 4 groups studied (P<.01). Group B had the highest fracture strength (1793.59 +/- 387.93 N). There was no significant difference among the fracture resistances of the other 3 groups (group A: 958.49 +/- 286.02 N; group C: 992.98 +/- 291.00 N; group D: 994.94 +/- 285.04 N).

CONCLUSION

Within the limitations of this study, not all of the post-core structures tested improved the strength of the endodontically treated teeth. Those prepared with a 2-mm dentin ferrule more effectively enhanced the fracture strength of custom cast post-core restored endodontically treated maxillary central incisors.

Children with class III malocclusion: development of multivariate statistical models to predict future need for orthognathic surgery

Until now, the literature does not provide an accurate model to predict the future need for orthognathic surgery in prepubertal patients with class III malocclusion. Because not all of these patients are candidates for later surgical correction, patient assessment and selection remain arbitrary with respect to diagnosis and treatment planning. The purpose of the present investigation was to analyze the value of classifying class III children before puberty into patients who can be effectively treated by orthopedic/orthodontic therapy alone and those who require orthognathic surgery. To obtain a robust model, the study design was multicentric (University Orthodontic Departments of Frankfurt, Heidelberg, and Würzburg). A total of 88 patients with class III malocclusion were grouped into orthopedic/orthodontic (n = 65) and surgery patients (n = 23), according to their records after puberty (mean age, 17 years three months). Discriminant analysis (DA) and logistic regression (LogR) were applied to 20 landmarks of the patients' cephalograms before puberty (mean age, nine years eight months) to identify the dentoskeletal variables that provide the best group separation and the best predictability of group membership, respectively. Both models were highly significant (P < .001), classifying 93.3% (DA) and 94.3% (LogR) of the patients correctly. The extracted variables were identical for both procedures: Wits appraisal, palatal plane angle, and individualized inclination of the lower incisors. The resulting equation of LogR was individual score = -7.968 - 1.323Wits - 0.363NL-NSL + 0.153[180 - (LI-ML) - (L1-ML(ind))]. We concluded that by means of multivariate statistics, prepubertal children with class III malocclusions may be classified into nonsurgery and surgery patients with high accuracy.

Macroscopic and microscopic analyses of linear enamel hypoplasia in Plio-Pleistocene South African hominins with respect to aspects of enamel development and morphology

This study uses macroscopic and microscopic methods to analyze the expression of linear enamel hypoplasia (LEH) in Plio-Pleistocene South African hominins. LEH is a developmental defect of enamel that is used in many anthropological contexts as a physiological stress indicator. Previous research has not settled the question as to whether differences in LEH expression exist between Paranthropus and Australopithecus and if they exist, to what extent these differences might be explained simply by taxonomic differences in enamel development and morphology rather than by differential stress experience. In this study, the analysis of LEH is conducted with respect to differences between Paranthropus and Australopithecus in aspects of enamel development and morphology that are thought to influence LEH expression. Two factors impacting LEH expression are considered: the duration of enamel formation, and the spacing of perikymata. It is predicted that if the first factor strongly influences the expression of LEH, then there should be fewer defects per tooth in Paranthropus because of its abbreviated crown formation spans (and fast extension rates) relative to Australopithecus. It is also predicted that because Australopithecus has more densely packed perikymata in comparable regions of the crown than Paranthropus, this taxon should, on average, have narrower defects than Paranthropus. To address these questions, 200 Australopithecus and 137 Paranthropus teeth were examined for LEH, and the analysis of defect width with respect to perikymata spacing was conducted on tooth impressions examined under a scanning electron microscope using INCA (Oxford Instruments) measurement software. Data support the first prediction: Australopithecus does have significantly more defects per canine tooth than Paranthropus. Data do not support the second prediction in large part because several Australopithecus specimens have wide groove defects in which perikymata are not visible and enamel is irregular. Such wide grooves are not predicted by perikymata spacing such that alternative explanations, including taxonomic differences in ameloblast sensitivity and the duration/severity of disruptions to enamel growth, must be considered.

Clinical study to compare two in-office (chairside) whitening systems

The objective of this clinical study was to compare the whitening/bleaching efficacy of two marketed in-office whitening systems: Discus Dental Zoom! Chairside System (25% hydrogen peroxide whitening gel) and Opalescence Xtra Boost Kit (38% hydrogen peroxide whitening gel), using the Vita Shade Guide and chromameter measurements. The study was an examiner-blind, parallel group, randomized and controlled clinical trial conducted in a dental setting. All subjects signed a study consent form prior to admission and were given Crest Regular Toothpaste and an Oral-B 40 straight-handle toothbrush to use during the study. Subjects received a supragingival prophylaxis followed by a screening eligibility Vita Shade assessment from which 22 subjects were selected. At baseline, all six maxillary anterior teeth were assessed with the Vita Shade Guide. Chromameter measurements were taken on either the right maxillary central or left maxillary central (tooth No. 8 or tooth No. 9). Subjects were assigned to one of two treatment groups, and had three applications of their assigned product. Following completion of the treatment phase, and on post-treatment Days 2 and 7, a visual examination of the condition of the oral soft tissues, together with a Vita Shade assessment on maxillary anterior teeth, a chromameter reading and a questionnaire regarding tooth sensitivity were completed. At the termination of the study, the statistical analysis of the Vita Shade scores indicated that both products significantly (p < 0.0001) lightened the color of the teeth. The average improvement was between 6 and 9 shade changes. Additionally, the Zoom! Chairside System was significantly better than the Opalescense Xtra Boost Kit at all time points: post-treatment (p < 0.0001); Day 2 (p < 0.004); Day 7 (p < 0.003). This difference was between 1 and 2 shade changes. The chromameter readings showed a significant difference in the overall color change (delta E) to a lighter color for both the Zoom! Chairside System and the Opalescence Xtra Boost Kit. Using delta E, the Zoom! Chairside System was directionally better than the Opalescense Xtra Boost Kit at Day 2 (p < 0.08), and significantly better at Day 7 (p < 0.025). Analysis of the composite parameters of delta E (L*, a*, b*) showed that no differences could be detected in the a* (redness) parameter. Changes were observed in the L* (brightness) and b* (yellow) parameters which paralleled the delta E differences. There were no significant differences in induced sensitivity between whitening systems at any time point.

Conservative management of a complication of neonatal teeth: a case report

A case report of neonatal teeth in a 4 month old male infant with ulceration on ventral surface of the tongue and its conservative management, is presented.

Dose-response analysis of short-term effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in three differentially susceptible rat lines

Line A, B, and C rats were selectively bred from TCDD-resistant Han/Wistar (Kuopio; H/W) and TCDD-sensitive Long-Evans (Turku/AB; L-E) rats. Line A rats are the most resistant to TCDD acute lethality followed by line B and line C rats. The resistance in line A rats is associated with a mutated H/W-type aryl hydrocarbon receptor (Ahr) allele (Ahr(hw)) and in line B rats the resistance is associated with an allele of an unknown gene B (B(hw)), while line C rats are almost as sensitive to TCDD as L-E rats. The dose-responses of characteristic short-term effects (day 8 postexposure) of TCDD were used to evaluate the efficacy (magnitude of effect) and potency relationships between these lines. Line A rats showed similar efficacies as line C (line A:line C efficacy ratio more than 0.7) for thymus weight, EROD activity, and incisor tooth defects. In contrast, efficacies in line A were decreased (efficacy ratios 0.19-0.37) for body weight change, serum bilirubin, and FFA levels, and serum ASAT activity. For most endpoints the efficacies in line B rats seem to be lower than in line C rats. The potencies were close to each other in line A and B rats, but somewhat lower than in line C rats. The results support our previous concept of two different AHR-mediated signaling pathways leading to dioxin type I and type II endpoints. Rats with the Ahr(hw/hw) genotype show a markedly decreased efficacy for type II endpoints, but B(hw) allele had only a minor effect on efficacies for most endpoints. Both H/W-type resistance alleles also decreased the potency of TCDD. However, the potency differences in short-term toxicity seem not to explain, at least alone, the differences seen in acute lethality among the rat lines.

Mandibular lateral incisor-canine transposition (Mn.12.C): a case report

Tooth transposition is a rare developmental anomaly of the teeth characterized by positional interchange of permanent tooth leading to disintegration in the alignment in the affected segment, shifting of midline and malocclusion of teeth. This article reports a rare case of Mn.12.C anomaly affecting right mandibular arch of a (11 year old) female child causing shifting of midline and crowding.

The prevalence and severity of dental fluorosis among 12-year-old schoolchildren in Jordan

OBJECTIVES

To assess dental fluorosis, provide base-line data among Jordanian children and to compare fluorosis in incisor teeth between areas with different fluoride levels.

DESIGN

Cross-sectional study among school children.

SAMPLE AND METHODS

A sample of 1878 subjects aged 12 years, 940 boys and 938 girls, were randomly selected from 128 schools in urban (69 schools) and rural (59 schools) areas. The Thylstrup & Fejerskov (TF) index was used to record the dental fluorosis on the labial surfaces of incisors.

RESULTS

A total of 18.5% of the children examined showed dental fluorosis. The difference in fluorosis between males (17%) and females (20%) was not statistically significant (P > 0.05). Children in rural areas had a higher prevalence of fluorosis (31.8%) than their counterparts in urban areas (11.3%), a difference that was statistically significant (P < 0.01).

CONCLUSIONS AND RECOMMENDATIONS

Findings suggest that there is a need for continued monitoring of mottling and further investigation into the fluoride intake from all sources in Jordan. However, there is a need to change the drinking water supplies in the southern region of Jordan. Active steps should also be taken to suppress emissions of vapours high in fluoride from phosphate plants to within acceptable limits.

Maxillary retention: is longer better?

Two different maxillary retention regimes were compared to ascertain if differences in posttreatment relapse existed. The patient pool was derived from subjects being treated at two orthodontic departments in the west of Scotland. Group 1 (20 patients) followed a 6 month regime using removable upper Hawley retainers for a period of 3 months full time and 3 months nights only. Group 2 (18 patients) followed a 1 year regime of 6 months full time and 6 months nights only. The results revealed that maxillary incisor alignment, as determined by Little's irregularity index, had relapsed by an average of 50 per cent of the end of retention value 3 months out of retention in Group 1 but only 23 per cent in Group 2. Although the actual mean values for relapse were 0.77 and 0.23 mm, respectively, seven subjects in Group 1 showed relapse of more than 3 mm as compared with only one in Group 2. This suggests that retaining a case for 1 year rather than 6 months is clinically beneficial.

Comparison of skeletal and dental morphology in asymptomatic volunteers and symptomatic patients with bilateral degenerative joint disease

The purpose of this study was to evaluate the effect of bilateral degenerative joint disease (BDJD) on the skeletal and dental patterns of affected individuals. There were 29 symptomatic female patients and 46 asymptomatic normal female volunteers. All study participants had bilateral high-resolution magnetic resonance scans in the sagittal (closed and open) and coronal (closed) planes to evaluate the temporomandibular joints. Linear and angular cephalometric measurements were taken to evaluate the skeletal, denture base and dental characteristics of the two groups. Analysis of variance was used to compare symptomatic subjects with control subjects. There was an overall retrusion of the maxilla and mandible with a clockwise mandibular rotation. The upper and lower denture bases were retruded. The upper incisor was more protruded, whereas the lower incisor was more retroclined in the symptomatic group. The overjet was also increased. This study suggests that subjects with BDJD may manifest altered craniofacial morphology. Clinicians should be aware of this possibility, especially for patients who are growing children and orthognathic surgery candidates.