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PubMed1997

Investigation of lay knowledge of the management of avulsed permanent incisors.

The prognosis of replanted avulsed permanent incisors depends largely on prompt and appropriate emergency management. The aim of this study was to investigate lay knowledge and attitudes in this respect. Postal questionnaires were sent to all physical education teachers, school nurses and secretaries, attendants in swimming baths and leisure centres and to 220 parents of teenage children in a defined area of North West England. The overall questionnaire response rate was 86.9%. Knowledge of methods of dealing with this problem was generally inadequate in both parents and the other groups. Although 53.6% of respondents claimed to have received first aid training only 3.1% could remember dental injuries being included. There was evidence that dental health education in this field can be effective, since the highest mean knowledge score was found in the 11.5% of respondents who recalled receiving advice from sources such as posters, magazines and newspapers. More than 80% of the respondents stated that they would not want to replant an avulsed incisor themselves, the main reason being lack of knowledge and training. It is suggested that there is a need for potentially effective dental health education in relation to this problem.

Caregivers↗
PubMed1999

Non-vital immature permanent incisors: factors that may influence treatment outcome.

This study examines the treatment of non-vital immature permanent incisors using the calcium hydroxide apexification technique. The objectives of the present study were to determine the speed and location of barrier formation and those factors discernible at presentation and during treatment which may be related to it. Forty-four non-vital immature incisors undergoing calcium hydroxide apexification were reviewed in detail. All cases were reviewed every 8-12 weeks for up to 18 months, or until apexification occurred. Details of the time and nature of the injuries and treatment were recorded. The degree of apical development prior to treatment was assessed, and barrier formation, location and time were noted. Mean time to barrier formation was 34.2 weeks (range 13-67 weeks). The strongest predictor of rapid barrier formation was the rate of change of calcium hydroxide and a barrier also formed more rapidly in cases with narrower initial apical width. There was evidence of displacement and a higher mean time for barrier formation in half of the cases. The presence of an abscess was the weakest predictor of rapid barrier formation and the effect was not significant (P = 0.280). The barrier was located at the apex in 28 cases (63.6%) and the distance from the barrier to the apex for the remaining 16 (36.4%) varied from 1 mm to 5 mm. The number of placements of calcium hydroxide varied from 1 to 4 with a mean of 1.9, and there was a higher mean number of calcium hydroxide placements in the cases where the barrier was located at the apex.

Analysis of Variance↗
PubMed2005

Study of calcium hydroxide apexification in 26 young permanent incisors.

This study was carried out in order to observe the effectiveness of apexification in young permanent incisors. The sample comprised 26 young permanent incisors with necrotic pulp and open apices. The time taken to obtain apical closure, its form and size were analysed in order to find out if closure was influenced by existing pathology or size of apex. The treated teeth were compared with their corresponding contralateral teeth. The test of McNemar and anova was used and a result of P = 0.05 was considered significant. Teeth with pretreatment apical shapes that were convergent or parallel all resulted in physiological apical shapes after treatment. Eight teeth had divergent apical shapes before treatment. Of these, one had a physiological shape, five ended with rounded apices and two teeth had straight apices post-treatment. Apical closure was obtained in 100% of the cases studied, of these 88.4% needed three to four sessions of calcium hydroxide treatment (an average of 3.23 sessions) in order to obtain apical closure, the average time employed was 12.19 months. Clinical symptoms resolved in all teeth that presented with symptoms. Preoperative symptoms did not affect outcome. Pathology of the tooth before treatment does not influence the time needed to obtain apical closure.

Analysis of Variance↗
PubMed2006

Root fracture of immature permanent incisors--a case report.

This 7-year-old girl experienced pain in her upper central incisors following a fall to the ground. Radiographic examination revealed immature upper central incisors with mid-root oblique and horizontal root fractures. Splinting was performed. When at 3 months, an electric pulp test was positive for both injured teeth, and after 5 months, the fracture lines had disappeared on the radiographs, the splint removed. After 2 years, clinical examination showed normal tooth color and position, with a positive response to the pulp test. Radiographs demonstrated continuous root development, although root canal narrowing was noted at the healed fracture sites.

Child↗
PubMed1999

Integrated orthodontic and restorative procedures for replacement of lost central incisors.

UNLABELLED: The use of adhesive material in association with many clinical procedures has contributed a great deal to solving functional and esthetic problems. Before adhesive techniques were known, dental procedures were more invasive and aggressive, especially in young patients. This article describes some integrated clinical procedures used to esthetically and functionally restore a mouth with traumatic loss of both central incisors. The treatment involved the orthodontic mesialization of the upper teeth toward the midline followed by anatomic and functional recovery through restorative dentistry. CLINICAL SIGNIFICANCE: This article describes some integrated clinical procedures that may effectively and conservatively improve the esthetic and functional results when a young patient loses the central incisors.

Child↗
PubMed1999

Bilateral dental fusion of the upper central incisors: a multidisciplinary approach.

UNLABELLED: The multidisciplinary treatment of a case of bilateral dental fusion of the upper central incisors with maxillary constriction, crowding, and palatal inversion of one of the lateral incisors is reported. The rarity with which this anomaly appears, along with its complex characteristics, often make it extremely difficult to treat. It requires the involvement of different specialists to find the most suitable treatment for each individual patient. CLINICAL SIGNIFICANCE: This particular case of bilateral dental fusion required the involvement of orthodontists, periodontists, endodontists, and restorative specialists. For the individual evaluation of these extremely complex cases, the esthetic and functional results to be reached must be assessed compared to treatment times and biologic and economical costs. The long-term prognoses of these complex therapies also must be borne in mind.

Adolescent↗
PubMed1990

The effect of age on the mechanical properties of the periodontal ligament in the incisor teeth of growing young rats.

Mechanical properties of the periodontal ligament of the incisor have been examined by pushing the tooth out of its surrounding alveolar bone in sections of the mandibles of rats from 3 to 24 weeks of age. The maximum load, failure energy in shear and elastic stiffness estimated from the load-deformation curves, showed a tendency to increase with age from 3 to 12 weeks but the maximum deformation did not. Age-related changes were not appreciable in all mechanical measures estimated from the stress-strain curves. It is suggested that increases in the maximum load and elastic stiffness from the load-deformation curves with age are closely related to those in the size of teeth or in the area of the periodontal ligament facing cementum. It is also suggested that qualitative and quantitative changes in the supporting tissues or in the collagen fibres/unit area of the periodontal ligament are minor from 3 to 24 weeks of age in the rat mandibular incisor.

Aging↗
PubMed2004

Unusual maxillary lateral incisors: case reports.

Root canal morphology is often complex and the number of root canals may vary for any type of tooth. Abnormalities in the root canal morphology of maxillary lateral inciors are rare. Maxillary lateral incisors can have two root canals, even though the dental literature supports their 100% single-canal anatomy. It is vital to consider the possibility of extra root canal(s), even in teeth with a low frequency of abnormal root canal anatomy. This report presents two cases of maxillary lateral incisors with two root canals.

Adult↗
PubMed1999

The prevalence of dental erosion in the maxillary incisors of 14-year-old schoolchildren living in Tower Hamlets and Hackney, London, UK.

The purpose of this study was to assess the prevalence of dental erosion in the maxillary incisors of a sample of 14-year-old schoolchildren and to explore the aetiological factors responsible for that erosion. The cross-sectionally design study took place in secondary schools in inner-city London, UK and involved 525, 14-year-old schoolchildren selected at random in a clinical examination and a self-completed questionnaire. The outcomes measures for dental erosion were; the prevalence, the area and depth of lesions and the risk factors. The prevalence of labial and palatal erosion was 16.9 per cent and 12 per cent respectively. Risk factors and behaviours including daily frequency of ingestion of acidic fruits and drinks, food vomiting, toothbrushing frequency, and swimming habits were not shown to have any relationship with the presence of erosion. It was concluded that the prevalence of erosion in the maxillary incisors of this sample was higher labially and lower palatally than in previously reported national figures. The risk factors which were investigated were not shown to have any relationship with the presence of erosion. Further investigations of these issues are necessary to establish whether or not dental erosion is a public health problem in the UK.

Acids↗
PubMed2002

Response of human jaw muscles to axial stimulation of the incisor.

The role of periodontal mechanoreceptors (PMRs) in the reflex control of the jaw muscles has thus far been mainly derived from animal studies. To date, the work that has been done on humans has been limited and confined to orthogonal stimulation of the labial surface of the tooth. The purpose of this study was to investigate the response of the masseter and digastric muscles in humans to controlled axial stimulation of the upper left central incisor, both before and during a local anaesthetic block of the PMRs. Ten neurologically normal young adult females were tested, each on two separate occasions to confirm the reproducibility of the results. It was found that the reflex response in the masseter was modulated by the rate of rise of the stimulus used and, to a lesser degree, the level of background muscle activity. There was little detectable change in the activity of the digastric muscle under the tested conditions and what was found could be attributed to cross-talk with the masseter. The reflex responses obtained were significantly different between subjects; however retesting the same subject on a different occasion yielded similar results. The results indicate that the most common response of the masseter muscle to brisk axial stimulation of the incisor is a reflex inhibition at 20 ms, followed by a late excitation at 44 ms. However, it is possible that this late excitation could be due to delayed action potentials and hence be artefactual. As the application of a local anaesthetic block removed or significantly reduced both of these responses, it was concluded that they originated from the PMRs. Unlike during orthogonal stimulation, slowly rising stimuli did not produce any excitatory reflex activity. This indicated a difference in jaw reflexes to forces applied in different directions, possibly due to the activation of different receptor types when stimulating the tooth in either the orthogonal or axial directions.

Adolescent↗
PubMed1988

A genetic, pathological and virological study of congenital hypotrichosis and incisor anodontia in cattle.

Two Friesian cows, half-sibs by a common dam, produced four bull calves with severe congenital hypotrichosis and incisor anodontia and three normal heifers by six unrelated Holstein, Friesian, Devon and Hereford bulls. The two dams, and their dam, had coats of a short, stubbly nature and the pigmented areas appeared rusty grey rather than black. Pathological examination of skin samples taken from multiple standardised sites from two of the affected calves showed a reduction in the number of large first-formed hair follicles. Smaller calibre hair follicles were present but, unlike those of normal neonatal calves, all were in the telogen (inactive) phase. Although the herd was infected with bovine virus diarrhoea virus there was no convincing evidence that the virus was implicated in the pathogenesis of these cases of congenital hypotrichosis with incisor anodontia. The family breeding information on the few severely affected and normal progeny and mildly affected and normal parents may be explained by the genetic hypothesis of an X-linked incompletely dominant gene.

Alopecia↗
PubMed1996

Ageing horses by an examination of their incisor teeth: an (im)possible task?

It is generally considered that the age of a horse can be determined by examining its incisor teeth. However, the criteria used to determine age from dental configurations differ widely. The existence of this variety of rules and guidelines was the challenge for the present examination. Detailed descriptions of the incisor teeth of 212 horses of registered age were recorded and the results were compared with the age criteria of various authors. The time at which teeth were shed and the appearance of dental stars seemed to be more reliable features than the disappearance of the cups. The disappearance of the marks occurred four years later than usually stated. Other criteria, such as the presence of the seven-year notch and Galvayne's groove, were too variable and inconsistent to be reliable for the determination of age.

Age Determination by Teeth↗
PubMed1977

Rate of growth of lower incisor teeth in the adult white rat.

A single dose of 14C was given to adult rats and the animals were sacrified 4 days later. The thickness of dentine formed during this period was measured in radioautographs of incisor teeth. It appeared that the thickness of dentine laid down per day was 15 microns. This rate was about one seventh of the rate of growth in immature incisors. No new dentine formation was observed in molar teeth.

Animals↗
PubMed1988

Autoradiographic investigation of effects of high-dose colchicine on dentinogenesis in rat incisors.

Twelve female Wistar rats received 1.5 mg/kg of colchicine (CLC) intravenously. Control animals were similarly injected with isotonic saline solution. The animals were killed 5 h, 24 h, 3 days and 7 days after injection. Ninety minutes prior to sacrifice, all animals received an intraperitoneal injection of 3H-proline. Autoradiograms of maxillary incisors showed that CLC increased the retention of the labeled precursor in the odontoblasts. It was also shown that the odontoblasts in the different sectors of the rat incisor present different sensitivities to the CLC action.

Animals↗
PubMed1977

The effect of a magnesium deficient diet and cortisone on the growth of the rat incisor.

Incisors of Mg-deficient rats showed a marked inhibition of eruption and a decrease in mitoses of apical tissues. Cortisone administration resulted in some increase in eruption rate and cell division though these remained below the values of Mg-supplemented controls. An improvement in gross condition and a less severe histopathology of incisor tissues were also observed in cortisone-treated rats.

Animals↗
PubMed1983

Target cells for 1,25-dihydroxyvitamin D3 in developing rat incisor teeth.

The concentration of radioactivity is observed in the nuclei of pulpal cells of maxillary and mandibular incisors of 20-day-old fetal rats, following injection of [3H]-1,25 (OH)2 vitamin D3. Cells in the odontoblast and ameloblast layers are essentially free of nuclear labeling. The radioactively labeled pulpal cells exist throughout the length of the incisors with the exception of the progenitor areas. The results indicate the presence of receptors for 1,25 (OH)2 vitamin D3 in pulpal cells, and suggest the effects of the hormone on these cells.

Ameloblasts↗
PubMed1988

The effects of upper incisor separation on the submandibular and sublingual glands of rats.

The effects of upper incisor separation on the submandibular and sublingual glands of rats were examined biochemically, immunohistologically, and radio-immunologically during 28 days of treatment. Lateral separation of the upper incisors by application of force from an orthodontic appliance caused significant enlargement of the sublingual and submandibular glands of rats by three and seven days, respectively, after the beginning of the orthodontic treatment. This enlargement was followed by a significant increase of both RNA and DNA content, with some evidence of hyperplasia and hypertrophy. The enlargement was also associated with a significant increase of substance P at early stages after treatment, suggesting the involvement of the sensory nerves. These changes were largely inhibited by phenoxybenzamine, an alpha-adrenergic blocker, but not by atropine or morphine. Wet weights and RNA contents of the sublingual glands were markedly reduced by atropine. In comparison with control animals, the enlarged submandibular glands of rats subjected to orthodontic treatment secreted additional proteins identical with those secreted by glands enlarged by chronic administration of isoproterenol. In addition, chemical sympathectomy with 6-hydroxydopamine and phenoxybenzamine stimulated the synthesis of these abnormal proteins, but atropine and morphine did not. In contrast, protease activities in the convoluted granular tubule cells in the submandibular glands were increasingly reduced after treatment, as seen in rats subjected to chronic treatment with isoproterenol. However, the submandibular and sublingual glands completely recovered after removal of the orthodontic appliance.

Animals↗
PubMed1991

The distribution of magnesium in developing rat incisor dentin.

Previous studies have shown that rat incisor dentin contains a considerable amount of magnesium that is distributed heterogeneously. The cementum-related dentin, especially its incisal portion, is richest in magnesium. It was the purpose of the present study to investigate the changes that occur in the magnesium content during dentin maturation. Cross-sections were prepared from rat incisors at the apical, middle, and incisal levels. By means of an electron microprobe, tracings were made of the Ca-, Mg-, and P- signal frequencies. Comparison of corresponding dentin layers within and between the cross-sections showed that the Mg/P molar ratio was always higher in the cementum-related dentin (CRD) than in the enamel-related dentin (ERD) and increased from the apex toward the incisal edge. Especially in the incisal cross-section, an increase in Mg/P was found from the older (peripheral) toward the younger (central) dentin layers. As the Mg/P ratio varied from 0.07 to 0.33, the Ca/P ratio was found to fluctuate from 1.48 to 1.15. The two ratios appeared to be highly correlated (r = -0.97; p less than 0.001), suggesting that Mg replaces Ca and is bound to phosphate.

Animals↗