Case report: A medieval case of molar-incisor-hypomineralisation.

INTRODUCTION: Molar-incisor-hypomineralisation (MIH) has been identified in recent years as a condition affecting the first permanent molars and, in some cases, the permanent incisors. Many factors have been suggested as to its aetiology. Examples of MIH have also been reported in skeletal remains in the past. These historical examples have, however, been for unknown individuals. CASE REPORT: A skull that has become available for dental examination that is uncertainly attributed to be that of Lady Eleanor Talbot (c.1436-1468) who ended her life as a Carmelite nun in Norwich (England). The dental findings of the examination showed enamel defects of molar teeth 36 and 46, as well as small areas on other molars, and striations of the enamel of permanent anterior teeth consistent with MIH. There is exposure of the roots of some maxillary teeth with resultant root caries. The presence of areas of enamel decalcification commensurate with 'Turner teeth' on 43 and 44 indicates that there were likely to have been periapical abscesses secondary to dental caries of the primary teeth. In addition, there is occlusal wear of all of teeth with extensive calculus and periodontal exposure of the roots of the mandibular incisors. Failed development or very early ante-mortem loss of premolars 15 and 25 is evident, as well as evidence in the same region of a large abscess cavity with extensive maxillary bone destruction. Healing cribra orbitalia, porosity, which is considered to be an indicator of nutritional stress, is visible on the superior aspect of the left orbit. CONCLUSION: A case of MIH is reported in a skull dating from the mid-15th century.

Nothing new under the heavens: MIH in the past?

AIM: This was to study an archaeological population of subadult teeth in 17th and 18th century skeletal material from a London (England) cemetery for enamel defects including molar-incisor-hypomineralisation (MIH). METHODS: Dentitions of 45 sub-adults were examined using standard macroscopic methods and systematically recorded. A total of 557 teeth were examined with a *5 lens and photographed. Ages of the individuals were estimated from their dental crown and root development stages and not from charts that combine tooth eruption with development stages. The dental age of the individual and the approximate age of onset of enamel defects was then calculated on the basis of the chronological sequence of incremental deposition and calcification of the enamel matrix. Affected enamel was graded macroscopically as: - Mild: <30% of the tooth's enamel surface area visibly disrupted (this encompasses the entire range reported in most other studies), Moderate: 31-49% of the tooth's enamel surface area visibly disrupted and Severe: >50% of the tooth's enamel surface area visibly disrupted. RESULTS: Of the total number of individuals 41 (93.2%) showed signs of enamel developmental dysplasia or MIH, 28 of them showing moderate or severe lesions of molars, primary or permanent (63.6% of the sample). Incisors and canines, though surviving much less often, showed episodes of linear hypoplasia. CONCLUSION: The extensive lesions seen on many of the molars displayed cuspal enamel hypoplasia (CEH). Many of these teeth also exhibited Molar Incisal Hypomineralisation (MIH).

Gross enamel hypoplasia in molars from subadults in a 16th-18th century London graveyard.

Dental Enamel Hypoplasia has long been used as a common nonspecific stress indicator in teeth from archaeological samples. Most researchers report relatively minor linear and pitted hypoplastic defects on tooth crown surfaces. In this work we report a high prevalence and early age of onset of extensive enamel defects in deciduous and permanent molars in the subadults from the post-medieval cemetery of Broadgate, east central London. Analysis of the dentition of all 45 subadults from the cemetery, using both macroscopic and microscopic methods, reveals disturbed cusp patterns and pitted, abnormal and arrested enamel formation. Forty-one individuals from this group (93.2%) showed some evidence of enamel hypoplasia, 28 of them showing moderate or extensive lesions of molars, deciduous or permanent (63.6% of the sample). Scanning Electron Microscope images reveal many molars with grossly deformed cuspal architecture, multiple extra cusps and large areas of exposed Tomes' process pits, where the ameloblasts have abruptly ceased matrix production, well before normal completion. This indented, rough and poorly mineralized surface facilitates both bacterial adhesion and tooth wear, and when such teeth erupt fully into the mouth they are likely to wear and decay rapidly. We suggest that this complex combination of pitted and plane-form lesions, combined with disruption of cusp pattern and the formation of multiple small cusps, should henceforth be identified as "Cuspal Enamel Hypoplasia."

Morbidity, rickets and long-bone growth in post-medieval Britain--a cross-population analysis.

BACKGROUND: Vitamin D deficiency rickets is associated with skeletal deformities including swollen rib junctions, bowing of the legs, and the flaring and fraying of the wrist and long-bone metaphyses. There is, however, scarce information on the direct effect of rickets on skeletal growth in either present or past populations. AIM: The study investigated the effect of vitamin D deficiency rickets on long-bone growth in two post-medieval skeletal populations from East London (Broadgate and Christ Church Spitalfields). Subsequently, inter-population growth variations in relation to non-specific environmental stress (dental enamel defects), industrialization, urbanization and socio-economic status during infancy (birth to 3 years) and early childhood (3-7 years) were examined. SUBJECTS AND METHODS: Data on long-bone diaphyseal length dimensions and stress indicators of 234 subadults from Anglo-Saxon, late medieval and post-medieval archaeological skeletal samples were analysed using both linear and non-linear growth models. RESULTS: Rickets had no effect on the growth curves for any of the long bones studied. However, pronounced variations in growth between the four populations were noted, mainly during infancy. The diaphyseal length of long bones of Broadgate were significantly smaller-per-age than those of Spitalfields and the other samples up to the age of 4 years, and were associated with a high prevalence of enamel defects during early infancy. CONCLUSION: Socio-economic status, rather than urbanization, industrialization or rickets, was the central factor behind the observed differences in growth among the post-medieval populations. The observed inter-population growth variations were only significant during infancy.

A 3 to 4 year study of single tooth hydroxylapatite coated endosseous dental implants.

OBJECTIVE: To evaluate the clinical effectiveness, common complications and maintenance associated with hydroxylapatite (HA) coated cylindrical implants when used to support single crowns. DESIGN: A prospective medium term clinical study of the Calcitek HA-coated implant. SETTING: Implant placement, crown fabrication and follow-up procedures were carried out at the Leeds Dental Institute, between 1990 and 1998. SUBJECTS AND METHOD: 26 patients (33 implants) participated in the trial. They were referred from general dental practitioners because of their suitability for single tooth implant placement. MAIN OUTCOME MEASURES: The implants were assessed using recognised clinical review procedures e.g. radiographs and soft tissue assessments. RESULTS: At exposure there was 100% implant integration. The cumulative survival rate over 4 years was 100%. In five implants there was cervical bone loss of more than 4 mm and these were classified as failing. This gave an overall cumulative success rate of 58% by year 4. CONCLUSION: The Calcitek HA-coated single tooth implant shows exceptionally high initial integration however, the longer term results suggest that the cervical bone level adjacent to the implant failed to establish a steady state. Doubts remain regarding the long-term prognosis of these cylindrical HA-coated implants.

A survey of U.K. centres on implant failures.

This study investigated the experience of endossoseus implants in the U.K. - how success rates compare with other countries; the common causes of failure; early detection, definition and treatment of the failing implant. Information was gathered by means of a questionnaire sent to 120 centres in the U.K. Thirty-nine centres responded to the survey, reporting on a total of 5328 implants which had been placed over an average time period of 6.5 years. A mean failure rate of 4.3% was reported in the mandible with 16% in the maxilla. The survey showed that 11 different implant systems were in use and that implants were used to support an overdenture in 56% of cases, and bridgework in 26%. The definition of the failing implant and the causes of failure were unclear, with a wide range of opinions given. A combination of methods were used to treat the failing implant including surgical techniques and chemotherapeutic agents, but the long-term success of these treatments was uncertain. Failure rates especially in the maxilla at some of the centres appear higher than have been previously suggested in the U.K. or abroad. Universal agreement on the criteria for 'success' and 'failure' of fixtures is needed along with agreed treatment protocols for the failing implant.

A 3- to 6-year study of overdentures supported by hydroxyapatite-coated endosseous dental implants.

PURPOSE: The purpose of this study was to evaluate the clinical effectiveness of hydroxyapatite-coated cylindrical implants to support overdentures. These implants were placed between 1990 and 1994 and have been followed up over a period of 3 to 6 years. MATERIALS AND METHODS: One hundred thirty-nine Calcitek dental implants were placed in 43 patients to support 14 maxillary and 30 mandibular overdentures. Standardized clinical review procedures were used. RESULTS: At exposure all the implants were found to be osseointegrated. To date only 7 implants (5%) have completely failed and two associated overdentures (5%) have been lost. The cumulative survival rate of all implants over 6 years was 92%. However, if failure is defined by the loss of more than 4 mm of cervical bone, 33 implants could be classified as being in the process of failing. Using these figures, interval success rates as low as 82% were found by year 6, and the cumulative success rate would fall to 39%. Maxillary survival and success rates were significantly lower than mandibular rates, at 38% and 10%, respectively, by year 5. CONCLUSION: Failure rates were higher in the maxillary arch, in poor quality bone, in smokers, and where implants were opposed by a natural dentition or an implant-supported prosthesis. The results suggest that the cervical bone level adjacent to the Calcitek cylindrical hydroxyapatite-coated implant failed to establish a steady state, particularly in the maxillary arch. Doubts remain regarding the long-term prognosis of these cylindrical implants.

Disposable trays for complete denture construction: a dimensional study of a type frequently used in the UK and of its suitability for the edentulous population.

This study compares the sizes of patients' edentulous arches with the shapes of a range of disposable stock trays from one manufacturer. In many dimensions there is considerable discrepancy between the two. It is concluded that, even with tray modification, it is almost impossible to obtain an accurate impression of the shape of the all-important sulcus regions. Such a conclusion emphasises the importance of obtaining further impressions in special trays which are modified appropriately.

Complete denture prescription--an audit of performance.

The quality of clinical records obtained during the various stages of complete denture construction was assessed in a survey conducted in five large dental laboratories in 1989. The most common fault in approximately half of 188 upper and 158 lower impressions was overextension in the labial and buccal sulci. Of the 87 occlusal records examined, the rims indicated the intended incisal relationship in about 50% of cases. The border of the eventual denture was defined by the technician rather than by the dentist in most instances. The post-dam was prescribed by the dentist in only 16% of the 50 trial dentures inspected. It is argued that a major cause of the lack of prescription is the level of the NHS fee, coupled with the fact that the laboratory expenses are deducted from that fee.

Use of image analysis in determining masticatory efficiency in patients presenting for immediate dentures.

Image analysis was used to determine masticatory efficiency and performance before and after placement of immediate dentures. Sections of cored carrot were used as the test food and the particle size of chewed expectorated food was measured using image analysis. Measurements were shown to be accurate and reproducible. Masticatory function of immediate-denture patients was also compared with a similar number of dentate individuals and experienced complete-denture wearers. Dentate subjects were significantly (P less than .01) more efficient at masticating the test food than were the complete- or immediate-denture wearers. The new method of measurement removes the necessity for the unpleasant and unhygienic sieving process previously used in this type of study.

Combined orthodontic and restorative management of oligodontia.

A 14-year-old patient suffering from congenital absence of almost her entire permanent dentition was referred by her GDP. Management of the case required an integrated orthodontic and restorative approach. The authors describe how the imaginative use of a combination of relatively simple techniques achieved a greatly improved dental appearance for the patient.