Persistence of deciduous molars in subjects with agenesis of the second premolars. (1/28)

The purpose of the present study was to investigate persistent primary second molars in a group of young people in their late twenties with agenesis of one or two second premolars. In 1982-83 it was decided, in connection with the orthodontic evaluation of 25 patients, to allow 35 primary molars (one or two in each patient) to remain in situ. All patients had mixed dentitions and agenesis of one or two premolars. The primary teeth were generally in good condition, although root resorption and infra-occlusion (compensated by occlusal composite onlays) occurred. In 1997, 18 of the 25 patients with a total of 26 retained primary molars were reexamined, comprising a clinical examination for exfoliation, extraction, loosening, and ankylosis, and a radiographic examination for root resorption, tooth morphology (crown and root), and alveolar bone contour. The examination showed that the degree of root resorption was unaltered in 20 of the 26 primary molars. In the permanent dentitions, where these primary molars persisted, there were no morphological deviations. Three of the six remaining primary molars had been extracted and three showed extensive resorption. In three of the 26 primary molars the infra-occlusion had worsened. The present study shows that persistence of primary second molars in subjects with agenesis of one or two premolars, and normal morphology of the permanent dentition can be an acceptable, semi-permanent solution for the patient. Whether this could also be an acceptable long-term solution will be shown by follow-up studies.  (+info)

The long-term survival of lower second primary molars in subjects with agenesis of the premolars. (2/28)

This study investigated 41 subjects, 13 male and 28 female, with agenesis of one or both lower second premolars, and with retained lower second primary molars. Intra-oral radiographs of 59 primary teeth were examined to judge the resorption of the mesial and distal roots, and were measured to record infra-occlusion of the primary teeth and tipping of the adjacent permanent teeth. The study commenced at 11-12 years of age. The mean age at the last measurement was 20 years 6 months (SD 3.62, range 13.6-31.8 years). During the observation period, only two of the 59 primary teeth were exfoliated. Five were extracted, two of which were replaced by upper third molar transplants. Beyond the age of 20 years no teeth were lost. Root resorption varied widely between individuals, but was slow. There was no typical pattern for development of infra-occlusion. Mean infra-occlusion was 0.47 mm (SD 1.13) at 11-12 years, increasing by less than 1.0 to 1.43 mm (SD 1.13) at age 17-18 years. At age 19-20 years, 55 per cent of teeth showed infra-occlusion between 0.5 and 4.5 mm, but 45 per cent showed no infra-occlusion. The space between the first molar and first premolar was a mean of 10.35 mm (SD 0.76) at age 10-12 years compared with the mean width of the second primary molar of 10.53 mm (SD 0.51). The space reduced by less than 0.5 mm to 9.95 mm (SD 1.50) at age 17-18 years. If primary molars are present at 20 years of age they appear to have a good prognosis for long-term survival.  (+info)

A radiographic comparison of apical root resorption after orthodontic treatment with a standard edgewise and a straight-wire edgewise technique. (3/28)

The purpose of this study was to compare the severity of apical root resorption occurring in patients treated with a standard edgewise and a straight-wire edgewise technique, and to assess the influence of known risk factors on root resorption incident to orthodontic treatment. The sample consisted of 80 patients with Angle Class II division 1 malocclusions, treated with extraction of at least two maxillary first premolars. Variables recorded for each patient included gender, age, ANB angle, overjet, overbite, trauma, habits, invagination, agenesis, tooth shedding, treatment duration, use of Class II elastics, body-build, general factors, impacted canines, and root form deviation. Forty patients were treated with a standard edgewise and 40 with a straight-wire edgewise technique, both with 0.018-inch slot brackets. Crown and root lengths of the maxillary incisors were measured on pre- and post-treatment periapical radiographs corrected for image distortion. Percentage of root shortening and root length loss in millimetres were then calculated. There was significantly more apical root resorption (P < 0.05) of both central incisors in the standard than in the straight-wire edgewise group. No significant difference was found for the lateral incisors. Root shortening of the lateral incisors was significantly associated with age, agenesis, duration of contraction period (distalization of incisors), and invagination, while root shortening of the central incisors was related to treatment group and trauma.  (+info)

Cellular events at the onset of physiological root resorption in rabbit deciduous teeth. (4/28)

For elucidation of how physiological root resorption of deciduous teeth is initiated, the cellular events that occur surrounding the root of rabbit deciduous teeth before and at the onset of physiological root resorption were observed by means of light and electron microscopy. In addition, the cytodifferentiation of odontoclasts during the initial phase of this root resorption was evaluated by histochemical staining of tartrate-resistant acid phosphatase (TRAP) activity as a marker odontoclasts and their precursors. The present investigation was focused on the physiological root resorption of the deciduous lower second molar of rabbits from Day 0-5 postnatally. At birth, the deciduous molar had not erupted yet, and no TRAP-positive cell could be found surrounding the tissue adjacent to the root of the deciduous tooth. TRAP-positive mononuclear cells were initially detected in the coronal portion of the dental follicle of the permanent tooth at Day 1 postnatally. Ultrastructurally, these mononuclear cells had moderate numbers of mitochondria and short-strand rough endoplasmic reticulum, as well as scattered free ribosomes throughout their cytoplasm. TRAP-positive mononuclear cells then appeared in the cementoblast layer immediately adjacent to the surface of the deciduous roots. These mononuclear cells projected cytoplasmic extensions between the cementoblasts and made contact with the cementum. At that time, cell-cell contact was frequently observed between these mononuclear cells and cementoblasts. During 3-5 days postnatally, the number of TRAP-positive multinucleate odontoclasts on the root surface gradually increased. They had well-developed ruffled borders and made typical resorption lacunae on the root surface of the deciduous tooth. During this early postnatal period, neither inflammatory cells nor necrotic tissue could be observed surrounding the deciduous root. This study demonstrates that the dental follicle of the permanent tooth as well as the connective tissue adjacent to the deciduous root might play important role in site- and time-specific recruitment, development, and activation of odontoclasts before and at the onset of physiological root resorption.  (+info)

The fate of 1,587 unrestored carious deciduous teeth: a retrospective general dental practice based study from northern England. (5/28)

OBJECTIVE: To investigate the outcome of non-restoration of carious deciduous teeth by means of a retrospective analysis of clinical case notes of children regularly attending two general dental practices and receiving preventive care. DESIGN: Using a carefully defined protocol the fate of deciduous teeth diagnosed as carious into dentine but symptomless and left unrestored was determined from the sequential examination of the clinical records of 481 children attending at least annually. RESULTS: The age at initial diagnosis of carious teeth ranged from 1-12 years with the majority of cavities (1,005) presenting by 6 years of age. In all, 1,587 teeth were followed until loss from the mouth. Of these, 190 (12%) were extracted because of pain and a further 60 (4%) became painful and were treated, leaving 1,337 (84%) that remained symptomless until being lost. Of the 1,337 symptomless teeth, 178 were extracted under general anaesthesia at the same time as painful ones. The final group of 1,159 (74%) teeth were exfoliated without causing pain after a mean survival time of 1,332 days. Excluding from the analysis the 178 extracted, but symptomless teeth, leaves a total of 1,409 teeth of which 18% gave pain and were extracted or treated and the remaining 82% exfoliated. The strongest determinant of pain was age on diagnosis, the other factors being tooth type and extent of the cavity when first seen. The carious teeth most likely to cause symptoms were found to be molars that developed cavities with pulpal involvement by the age of 3 years, 34% of which caused pain. In contrast, those least likely to cause pain were carious molar teeth presenting without pulpal involvement after 8 years, only 6% of which produced symptoms. CONCLUSION: In these patients, the majority of unrestored carious deciduous teeth remain symptomless until shed. The results provide evidence to aid the treatment planning of carious deciduous teeth in children regularly receiving regular preventive dental care.  (+info)

SHED: stem cells from human exfoliated deciduous teeth. (6/28)

To isolate high-quality human postnatal stem cells from accessible resources is an important goal for stem-cell research. In this study we found that exfoliated human deciduous tooth contains multipotent stem cells [stem cells from human exfoliated deciduous teeth (SHED)]. SHED were identified to be a population of highly proliferative, clonogenic cells capable of differentiating into a variety of cell types including neural cells, adipocytes, and odontoblasts. After in vivo transplantation, SHED were found to be able to induce bone formation, generate dentin, and survive in mouse brain along with expression of neural markers. Here we show that a naturally exfoliated human organ contains a population of stem cells that are completely different from previously identified stem cells. SHED are not only derived from a very accessible tissue resource but are also capable of providing enough cells for potential clinical application. Thus, exfoliated teeth may be an unexpected unique resource for stem-cell therapies including autologous stem-cell transplantation and tissue engineering.  (+info)

Cementum-like tissue deposition on the resorbed enamel surface of human deciduous teeth prior to shedding. (7/28)

Prior to the shedding of human deciduous teeth, odontoclastic resorption takes place at the pulpal surface of the coronal dentin, and this resorption occasionally extends coronally from the dentinoenamel junction into the enamel. After the end of resorption, however, the resorbed enamel surface is repaired by the deposition of a cementum-like tissue. Using this phenomenon as an observation model, in this study we examined the sequence of cellular and extracellular/matrix events involved in the enamel resorption repair by light and electron microscopy. As the odontoclast terminated its resorption activity, it detached from the resorbed enamel surface; thereafter, numerous mononuclear cells were observed along the resorbed enamel surface. Most of these mononuclear cells made close contact with the resorbed enamel surface, and coated pits or patches were observed on their plasma membrane facing this surface. Furthermore, they frequently contained thin needle- or plate-like enamel crystals in their cytoplasmic vacuoles as well as secondary lysozomes. Following the disappearance of these monononuclear cells, the resorbed enamel surface now displayed a thin coat of organic matrix. Ultrastructurally, this organic layer was composed of a reticular and/or granular organic matrix, but contained no collagen fibrils. Energy-dispersive X-ray microanalysis of this thin organic layer in undecalcified sections revealed small spectral peaks of Ca and P. Cementum-like tissue initially formed along this thin organic layer, increased in width, and appeared to undergo mineralization as time progressed. The results of our observations demonstrate that regardless of type of matrix of dental hard tissues, tooth repair may be coupled to tooth resorption, and suggest that mononuclear cells and an organic thin layer found on the previously resorbed enamel surface may play an important role in the repair process initiated after resorption of the enamel.  (+info)

The prevalence and severity of oral impacts on daily performances in Thai primary school children. (8/28)

BACKGROUND: Traditional methods of measuring oral health mainly use clinical dental indices and have been complemented by oral health related quality of life (OHRQoL) measures. Most OHRQoL studies have been on adults and elderly populations. There are no systematic OHRQoL studies of a population-based sample of children. The objective of this study was to assess the prevalence, characteristics and severity of oral impacts in primary school children. METHODS: Cross-sectional study of all 1126 children aged 11-12 years in a municipal area of Suphanburi province, Thailand. An OHRQoL measure, Child-Oral Impacts on Daily Performances index (Child-OIDP) was used to assess oral impacts. Children were also clinically examined and completed a self-administered questionnaire about demographic information and oral behaviours. RESULTS: 89.8% of children had one or more oral impacts. The median impact score was 7.6 and mean score was 8.8. Nearly half (47.0%) of the children with impacts had impacts at very little or little levels of intensity. Most (84.8%) of those with impacts had 1-4 daily performances affected (out of 8 performances). Eating was the most common performance affected (72.9%). The severity of impacts was high for eating and smiling and low for study and social contact performances. The main clinical causes of impacts were sensitive tooth (27.9%), oral ulcers (25.8%), toothache (25.1%) and an exfoliating primary tooth (23.4%). CONCLUSIONS: The study reveals that oral health impacts on quality of life in Thai primary school children. Oral impacts were prevalent, but not severe. The impacts mainly related to difficulty eating and smiling. Toothache, oral ulcers and natural processes contributed largely to the incidence of oral impacts.  (+info)