Simultaneous determination of stable carbon, oxygen, and hydrogen isotopes in cellulose.

A technological development is described through which the stable carbon-, oxygen-, and nonexchangeable hydrogen-isotopic ratios (δ(13)C, δ(18)O, δ(2)H) are determined on a single carbohydrate (cellulose) sample with precision equivalent to conventional techniques (δ(13)C 0.15‰, δ(18)O 0.30‰, δ(2)H 3.0‰). This triple-isotope approach offers significant new research opportunities, most notably in physiology and medicine, isotope biogeochemistry, forensic science, and palaeoclimatology, when isotopic analysis of a common sample is desirable or when sample material is limited.

The cervical wedge-shaped lesion in teeth: a light and electron microscopic study.

BACKGROUND: The cervical non-carious wedged-shaped lesion is controversial in that its aetiology may involve attrition, erosion, abrasion and stress-corrosion (abfraction). This study examined the histopathology of anterior teeth with cervical wedge-shaped lesions by light and electron microscopy to elucidate their pathogenesis. METHODS: Ten undecalcified human teeth with cervical lesions were available for investigation. Patency of the dentine tubules was tested using red dye penetration from the pulp chamber. The morphology of normal and sclerotic dentine adjacent to the cervical wedge-shaped lesions was investigated by scanning electron microscopy. The numbers and diameters of dentinal tubules were measured at different levels beneath the surfaces of the lesions. RESULTS: The gross and microscopic features of the worn teeth were described. Red dye penetration tests showed white tracts of sclerotic tubules contrasted with red tracts of patent tubules. Numbers of tubules per square area and diameters of patent and sclerotic tubules varied at different levels within the dentine due to deposits of intratubular dentine. CONCLUSIONS: The cervical wedge is shaped by interactions between acid wear, abrasion and dentinal sclerosis. No histopathological evidence of abfraction was found. Clinical diagnosis, conservation and restoration of non-carious cervical lesions need to take into account the extent of sclerotic dentine beneath wedge-shaped lesions.

Incisor disocclusion in rats affects mandibular condylar cartilage at the cellular level.

UNLABELLED: The effect of altered occlusion on the mandibular condylar cartilage remains unclear. OBJECTIVE: This study investigated the effect of unilateral incisor disocclusion on cartilage thickness, on mitotic activity and on chondrocytes maturation and differentiation in the mandibular condylar cartilage of rats. DESIGN: The upper and lower left incisors were trimmed 2mm every second day in five rats. In other five rats, the incisor occlusion was not altered. Condylar tissues from both sides of each mandible were processed and stained for Herovici's stain and immunohistochemistry for bromodeoxyuridine (BrdU), transforming growth factor-beta1 (TGF-beta1), alkaline phosphatase (ALP) and osteocalcin (OCN). Measurements of cartilage thickness and the numbers of immunopositive cells for each antibody were analysed by one-way analysis of variance (ANOVA). RESULTS: No significant differences were observed in cartilage thickness after 7 days of unilateral incisor disocclusion. However, the numbers of immunopositive cells for BrdU as a marker of DNA synthesising cells, TGF-beta1 as a marker of chondrocytes differentiation, and ALP and OCN as markers of chondrocytes maturation, were significant higher in the cartilage cells on both sides when incisor occlusion was unilaterally altered. Interestingly, alkaline phosphatase was highly expressed on the condylar side of incisor disocclusion, whereas osteocalcin was highly expressed on the side opposite to the incisor disocclusion. CONCLUSIONS: It is demonstrated that after 7 days, unilateral incisor disocclusion affects the mandibular condylar cartilage at the cellular level by increasing the mitotic activity and by accelerating chondrocytes maturation. Chondrocytes maturation appears more accelerated on the side opposite to incisor disocclusion.

Mouse cellular cementum is highly dependent on growth hormone status.

Cementum is known to be growth-hormone (GH)-responsive, but to what extent is unclear. This study examines the effects of extremes of GH status on cementogenesis in three lines of genetically modified mice; GH excess (giant), GH antagonist excess (dwarf), and GH receptor-deleted (GHR-KO) (dwarf). Age-matched mandibular molar tissues were processed for light microscope histology. Digital images of sections of first molar teeth were captured for morphometric analysis of lingual root cementum. Cross-sectional area of the cellular cementum was a sensitive guide to GH status, being reduced nearly 10-fold in GHR-KO mice, three-fold in GH antagonist mice, and increased almost two-fold in giant mice (p < 0.001). Cellular cementum length was similarly influenced by GH status, but to a lesser extent. Acellular cementum was generally unaffected. This study reveals cellular cementum to be a highly responsive GH target tissue, which may have therapeutic applications in assisting regeneration of the periodontium.

Dental erosion in asthma: a case-control study from south east Queensland.

BACKGROUND: Asthma medication places patients at risk of dental erosion by reducing salivary protection against extrinsic or intrinsic acids. But patterns of lesions in asthmatics may differ from patterns in non-asthmatics, because gastro-oesophageal reflux (GOR) is found in 60 per cent of asthmatics. METHODS: The lesions in 44 asthma cases were compared to those of age and sex match controls with no history of asthma or medications drawn from the dental records of 423 patients referred concerning excessive tooth wear. The subjects were 70 males age range 15 to 55 years and 18 females age range 18 to 45. Anamnestic clinical data were compared between the two groups. Models of all 88 subjects were examined by light microscopy, and wear patterns were recorded on permanent central incisor, canine, premolar and first molar teeth. RESULTS: Clinical differences were a higher incidence of tooth hypersensitivity, xerostomia, salivary gland abnormalities, gastric complaints, and self induced vomiting in the cases. No differences were found between the cases and controls on citrus fruit and acid soft drink consumption. More occlusal erosion sites were found in cases, whereas more attrition sites were found in the controls. There were no significant differences in palatal erosion on maxillary anterior teeth found between cases and controls. Lingual erosion of the mandibular incisors, found only in GOR patients, was not observed. CONCLUSIONS: A higher incidence of erosion was found in asthmatics. Gastro-oesophageal reflux symptoms were not associated with the sign of lingual mandibular incisor erosion. The clinical significance is that asthmatics are at risk of dental erosion from extrinsic acid, but GOR does not appear to contribute in a site-specific manner.

Cupped lesions of early onset dental erosion in young southeast Queensland adults.

BACKGROUND: Dental erosion manifests as cupped lesions on cusp apices and in fissures of teeth in patients from southeast Queensland referred with excessive tooth wear. When found in young adults, these lesions may indicate early onset of active dental erosion. If the numbers and extent of cupped lesions increase with age, erosion may be a slow cumulative process. METHODS: This cross-sectional study recorded the presence or absence and the relative sizes of cupped lesions from all cusps and occlusal fissures on premolar and permanent molar teeth from study models by image analysis. Type-specimens of cupped lesions were examined. RESULTS: The incidence by tooth reflected time in the mouth, post-tooth emergence. A linear increase in lesion number and size, with age, was found. However, cupped lesions occurred on mandibular first molar cusp apices as often, and attained greater extent, in adults under 27 years compared with older subjects. CONCLUSION: Marked differences were found between lesion number and size, between maxillary and mandibular molar sites that reflect differences in salivary protection against dental erosion. The significance of this study is that the mandibular first permanent molar indicates the age of onset and severity of dental erosion.

The effect of glucocorticosteroid treatment on dentine formation in the Lewis rat, a histological study.

Glucocorticosteroids are widely used in the treatment of chronic illnesses and have been reported to cause premature obliteration of the pulp space. During the active stages of dentinogenesis, odontoblasts are growth hormone receptor (GHr) positive. The aims of this study were to determine if the glucocorticosteroid, prednisone, affected the rate of dentine deposition and odontoblast expression of GHr in the rat molar. Following subcutaneous injection of 0.05 mg/kg, 1.0 mg/kg or 5.0 mg/kg prednisone for 20 days, immature and mature molars from rats aged 3 and 6 weeks respectively, were examined histologically. Distribution of GHr expression was determined immunohistochemically. No morphological differences were observed in molars from prednisone treated animals. Prednisone did not appear to enhance dentine deposition in immature molars but in mature molars significantly increased dentine deposition on the roof of the pulp chamber at a dosage of 5.0 mg/kg (p < 0.001). In all immature molars, odontoblasts and pulp cells expressed GHr immunoreactivity. In mature molars, odontoblasts and pulpal cells from controls did not show GHr immunoreactivity. However, odontoblasts and pulp cells were GHr immunoreactive in mature molars from animals treated with prednisone.

Dental cervical lesions associated with occlusal erosion and attrition.

Acid demineralization of teeth causes occlusal erosion and attrition, and shallow and wedge-shaped cervical lesions putatively involving abfraction. From 250 patients with tooth wear, 122 with cervical lesions were identified. From epoxy resin replicas of their dentitions, associations of occlusal attrition or erosion or no wear with cervical lesions were recorded at 24 tooth sites (total 2928 sites). Criteria used to discriminate occlusal attrition from erosion, and shallow from grooved, wedge-shaped or restored cervical lesions were delineated by scanning electron microscopy. A 96 per cent association was found between occlusal and cervical pathology. Shallow cervical lesions were more commonly found in association with occlusal erosion. Wedge-shaped lesions were found equally commonly in association with occlusal erosion, as with attrition. Grooved and restored cervical lesions were uncommon. Differences were appreciated in the associations within incisor, canine, premolar and molar tooth sites which related more to the site-specificity of dental erosion than to attrition from occlusal forces. Non-carious lesions on teeth then have multifactorial aetiology and pathogenesis in which erosion and salivary protection play central roles. Dentists should primarily consider erosion in the diagnosis, prevention and treatment of tooth wear.

Tooth movement and vascularity of the dental pulp: a pilot study.

The effect of orthodontic tooth movement on the dental pulp was assessed histologically in twelve subjects. The participants in this study required the extraction of at least two maxillary first premolars for orthodontic treatment. They were asked to wear a maxillary removable appliance that acted to move a randomly determined premolar in a buccal direction. The appliance was designed to avoid contacting the contra-lateral tooth that was used as the matched control. The appliance was initially worn for a week to ensure patient comfort and cooperation. The appliance was then activated and the patient dismissed. After two weeks, the appliance was reactivated. Both the control and experimental teeth were extracted three weeks later, on the thirty-fifth day of activated appliance wear. The teeth were fixed, decalcified and sectioned. The sections were stained with haematoxylin and eosin for histological examination. This investigation demonstrated that orthodontic tooth movement did have an effect upon the dental pulp, causing vasodilation in the pulp of an orthodontically stressed tooth.

Dental erosion and bruxism. A tooth wear analysis from south east Queensland.

Tooth-tissue loss from erosion and attrition from bruxism were associated findings in 104 patients with excessive toothwear from South East Queensland. Approximately one-third of these subjects had been given a diagnosis of bruxism prior to referral. After a structured interview and clinical examination, the prevailing diagnosis was tooth erosion associated with occupational or sports-related dehydration, and one-third of the subjects were provisionally classified as bruxers. Eight items of clinical history and examination, designed to differentiate bruxers from non-bruxers, were analysed retrospectively from their records. These clinical items, by which the diagnosis of bruxism might be made, segregated the subjects into three groups of equal size, 'bruxers, possible bruxers and non-bruxers,' by a notional score for bruxism. The presence of occlusal attrition or erosion on the sextants of the dentitions was determined by scanning electron microscopic criteria on epoxy resin dental casts. The incidence of attrition versus erosion was compared between the three groups. The hypothesis was that attrition would be found on more sextants of bruxers than non-bruxers. Erosion predominated in virtually all sextants in all three groups, to the virtual exclusion of attrition in the molar sextants. The exception was the mandibular anterior sextant, where more sextants in bruxers were affected by attrition. Thus extrinsic or intrinsic acid erosion was strongly associated with occlusal tooth wear found in bruxers. Conversely, tooth-wear patterns were unreliable indicators of a bruxing habit, for attrition alone was often found on acid-exposed teeth. Thus, even if a patient is suspected of having bruxism, dental erosion is more likely the cause of tooth-tissue loss than attrition, especially in the dehydrating environment of South East Queensland.

Prior fluoridation in childhood affects dental caries and tooth wear in a south east Queensland population.

Fluoride exposure in early life has an effect on dental caries experience, but does it affect tooth wear in later life? Ninety-six South East Queensland subjects were studied. Their histories revealed three groups; a fluoride (F-) in water supply, a F- by supplement, and a non-fluoridated (non F-) group. Significantly higher caries experience was found in the non-F- group compared with F- in water group and the F- supplement group. No statistically significant difference in caries experience was found between the F- in water and F- supplement groups. Overall, tooth wear affected more sextants of the dentitions of non-fluoridated, high-caries subjects than of fluoridated low-caries subjects. Comparisons of wear patterns on sextants of the dentitions, between the fluoridated and non-fluoridated groups, revealed that in sextants where attrition was present no marked differences were discernible between the two groups. However, in most sextants where incisal, palatal, occlusal or non-occlusal erosion was found, this type of wear was commoner in non-fluoridated subjects. The exceptions were the mandibular molar sextants, where prior fluoride-exposure did not appear to protect against occlusal erosion patterns. This study showed that fluoride exposure during the first 12 years of life, which reduced dental caries in this population, may also protect teeth from wear to some extent.

A quantitative cytological study of lesional and non-lesional mucosa in oral lichen planus.

Smears of buccal mucosa, dorsal surface of the tongue and floor of mouth were taken from 10 patients with histologically confirmed oral lichen planus and 12 healthy age- and sex-matched controls. In buccal smears, no significant differences in cytoplasmic and nuclear areas were observed between lesional, adjacent non-lesional and control tissues. However, the cytoplasmic area in smears from lichen planus lesions on the dorsum of the tongue and adjacent clinically normal mucosa was reduced compared with healthy controls. The cytoplasmic: nuclear ratio in smears from clinically normal floor of mouth in oral lichen planus was similarly reduced. Papanicolaou-stained smears from buccal lichen planus showed increased keratinization compared with normal buccal mucosa. These findings demonstrate that quantitative cytology can detect both cytoplasmic and nuclear changes in oral lichen planus.

In situ hybridization evidence for a paracrine/autocrine role for insulin-like growth factor-I in tooth development.

Insulin-like growth factor-I(IGF-I) has both metabolic and growth-promoting activities in many cell and tissue types. Although IGF-I is present in serum, it is also thought to have important autocrine and paracrine functions. Immunohistochemistry for IGF-I and its receptor have shown that IGF-I is synthesised locally by the tooth forming cells which exhibit both the IGF-I and the growth hormone receptors. This concept required to be tested by in situ hybridization. Using a digoxigenin-labelled synthetic oligodeoxyribonucleotide probe for IGF-I, we investigated the distribution of IGF-I mRNA in the continuously erupting rat incisor by in situ hybridization. The distribution and intensity of the hybridization signal varied with the developmental stage of the rat incisor. The cells of the apical loop expressed a positive hybridization signal, but the earliest polarised odontoblasts and pre-ameloblasts did not show any positive signal. The onset of enamel secretion was accompanied by a strong hybridization signal in the secretory ameloblasts as well as the odontoblasts. Maturation ameloblasts also demonstrated IGF-I message in their cytoplasm as well as their nuclei. The cells of the pulp and the dental follicle were consistently negative. However, in the adjacent alveolar bone, the signal was high in the osteoblasts and osteoclasts. These findings support the notion of paracrine or autocrine function for IGF-I in tooth development.

Human immunodeficiency virus seropositivity in critically ill neonates in the south Bronx.

Cord blood was anonymously screened to determine the prevalence of human immunodeficiency virus (HIV) seropositivity in neonates admitted to the neonatal intensive care unit (NICU) at the Bronx Lebanon Hospital Center, located in the South Bronx. We speculated that factors leading to admission to the NICU such as low birth weight, prematurity and being small for gestational age would also be associated with an increased prevalence of HIV seropositivity. During the study period the prevalence of HIV seropositivity was 11.6% in the NICU population. There was no significant difference in maternal age, gravidity, race and sex in HIV-seropositive vs. HIV-seronegative newborns. There was a significantly increased incidence of maternal drug use (P less than 0.01), babies small for gestational age (P less than 0.005) and microcephaly (P less than 0.02) in seropositive vs. seronegative NICU babies. The results of this study suggest that the NICU population may comprise a significant number of infants of HIV-infected mothers.

Hereditary opalescent dentine: variation in expression.

A family is described in which two females are more severely affected by hereditary opalescent dentine than the males. The genealogy of this family does not provide an accepted pattern of inheritance for this dentine anomaly. This may indicate that there is considerable variation in inheritance patterns for hereditary opalescent dentine and that this trait does not always exhibit 100 percent penetrance.

Tooth enamel structure in the koala, Phascolarctos cinereus: some functional interpretations.

The purpose of this study is to determine whether the structural organization of Pattern 2 marsupial enamel in the Koala is disposed to resist wear on the sectorial crests of the molar teeth. The orientation of wear on the crests is uniformly delineated by parallel scratches on their polished surfaces. Twin blades, a leading and a trailing edge of enamel are formed on each crest by wear into dentine on which the differential wear at enamel to dentine interfaces indicates that the direction of wear is labial to lingual. 96 leading and trailing edges from 12 koala molars were examined by light and scanning electron microscopy as ground sections, polished and etched surfaces or polished and etched whole mount preparations sputter coated with gold. The results showed that the leading and trailing enamel edges are different in their thicknesses, and in the course of their rods. The rods in the thinner leading edge are angled at 25 degrees to the long axis of the tooth and cross the worn surface at 60-70 degrees. Trailing rods run at 5 degrees to the long axis to cross the worn surface at 90 degrees. The inter-rod sheets run parallel to the wear striations and thus hold the rods in palisades angled in the leading edge particularly to resist the vector of the occlusal forces in the direction of wear. Crystals in the rods emerge roughly perpendicular onto the worn surface which makes them more resistant to abrasion than those in the inter-rod substance which lie parallel to the worn surface and are more readily removed. Koala enamel on the sectorial crests is thus a simple Pattern 2 rod packing pattern but the angles of the rods and the alignment of the inter-rod substance appear to be adapted to resist occlusal forces and abrasion.

Focal palmoplantar and gingival hyperkeratosis syndrome: report of a family, with cytologic, ultrastructural, and histochemical findings.

An Australian family in which two members were affected by focal palmoplantar and gingival mucosal hyperkeratosis syndrome is reported. The propositus and his daughter had symptoms which suggested that esophageal lesions might be present. In view of the association of tylosis with esophageal carcinoma in other families, both patients were investigated by barium swallow or endoscopy. No esophageal lesions were found. Previously unreported paranuclear bodies were described in the keratinocytes of the spinous and granular cell layers of the finely papillated gingival epithelium of the propositus. Similar paranuclear bodies, although rare, were identified in cytologic smears from the four members of the family examined, two of whom had slight whitening of the mucosa of the retromolar pads only. By electron microscopy and histochemistry, these bodies were characterized as condensations of tonofilaments and not heteromorphic keratohyalin.