Risk of renal cell carcinoma after kidney transplantation

Dental trauma occurs very often in children and its consequences vary from tiny fractures to the complete avulsion of the tooth. According to Andreasen, 86.5% of incidents of dental trauma suffered by preschool children cause injury to maxillary primary incisors, whereas only 0.5% cause injury to primary molars. This case report is of a male patient aged 7 years who had fallen down a month before, struck his chin against a step, and fractured the maxillary and mandibular left primary second molars (65 and 75) and the mandibular right primary second molar (85). The 65 required only smoothing of sharp edges, 75 received endodontic treatment and a stainless steel crown, and 85 was extracted and a space maintainer fitted. The early diagnosis of fractures of posterior teeth is very important; a thorough examination of all posterior teeth should be made, especially when child suffers trauma to the chin region.     

Replacing posterior teeth with freestanding implants: four-year prosthodontic results of a prospective study

This article presents prospective four-year prosthetic results of the placement of 432 posterior freestanding, conventionally cemented prosthetic tooth implants in posterior edentulous spaces using the Bicon Dental Implants system (Bicon Dental Implants). Over four years, 0.74 percent of the abutments loosened, 0.5 percent of the abutments fractured, and 2.47 percent of the crowns experienced porcelain fracture, (all porcelain fractures occurred at time of placement). This low rate of problems appears to make free-standing single-tooth implant restorations a reliable solution to treating posterior edentulism.     

Human leucocyte antigens in pregnant women with pre-eclampsia associated with intrauterine growth retardation and in normal controls

Prenatal exposure to anticonvulsant medication has been shown to cause craniofacial dysmorphology, prenatal growth retardation, hypoplastic nails and phalanges, and visceral abnormalities. In this study we examined maxillary and mandibular stone dental casts (45) and panoramic radiographs (39) from 45 individuals with ages 4.5 to 22.0 years for changes in mesiodistal crown size of deciduous and permanent teeth, and the presence of dental anomalies. These individuals had been exposed prenatally to antiepileptic drugs (AEDs). Mesiodistal crown diameters were measured from the dental casts and converted into standard scores (Z), using published normative data from the University of Michigan Longitudinal Craniofacial Growth Series. A significant increase in mesiodistal crown dimensions of the posterior maxillary teeth was observed, specifically in primary molars and their permanent premolar successors, as well as permanent molars. Changes in tooth size were more common in females than in males. Dental maturity, assessed using the panoramic radiographs, was equal to chronologic age. An increased frequency of hypodontia was the only notable dental anomaly.     

Postoperative complications after Mainz pouch construction--with emphasis on measures to deal with narrowing of the duct aperture

Cutaneous sinus tracts in the face and neck region are often dental in origin. The purpose of this study was to characterize the clinical features and treatment of 37 consecutive cases of odontogenic cutaneous sinus tracts, collected and reviewed in a 15-year period. More than half of the patients (21 cases, 57%) were referred from medical doctors, particularly plastic surgeons and dermatologists. The sinus tracts were associated with caries (26 cases), incomplete endodontic treatment (7), crown fracture (2), vertical root fracture (1) and impacted mandibular third molar (1). They occurred most often in adolescents and adults (30 cases, 81%). The most common causative teeth were mandibular teeth (34 teeth, 85%). The chin, submental, and cheek areas were the most common sites of sinus tracts (30 cases, 81%). The majority of causative teeth (32 teeth, 80%) were treated endodontically. All fistulas healed uneventfully after proper dental treatment, without cosmetic surgery. In 63% (20 cases) of the recorded cases, complete resolution occurred within 8 weeks. Half of the patients had had fistulas for more than 6 months before receiving dental treatment, demonstrating that delays in proper diagnosis and treatment were common. As most patients suffered from unnecessary medication or surgery due to the delay of dental treatment, early dental consultation and treatment is important. Conventional endodontic treatment should be the treatment of choice if the tooth is salvageable. The increasing incidence of incomplete endodontic treatment in association with the occurrence of sinus tracts indicates that standardized endodontic therapy should be emphasized for prevention.     

Novel LQT-3 mutation affects Na+ channel activity through interactions between alpha- and beta1-subunits

This study describes mesial and distal enamel thickness of the permanent posterior mandibular dentition. The sample comprised 98 Caucasian adults (59 males, 39 females) 20 to 35 years old. Bitewing radiographs of the right permanent mandibular premolars and first and second molars were illuminated and transferred to a computer at a fixed magnification via a video camera. Enamel and dentin thicknesses were identified and digitized on the plane representing the maximum mesiodistal diameter of each tooth. The results showed that there were no significant sex differences in either mesial or distal enamel thickness. Enamel on the second molars was significantly thicker (0.3 to 0.4 mm) than enamel on the premolars. Distal enamel was significantly thicker than mesial enamel. There was approximately 10 mm of total enamel on the four teeth combined. Assuming 50% enamel reduction, the premolars and molars should provide 9.8 mm of additional space for realignment of mandibular teeth.     

Strength of core build-up materials in endodontically treated teeth

PURPOSE: To compare the in vitro strength of a reinforced glass ionomer and a light-cured glass ionomer used as an alternative to amalgam in core construction to restore endodontically treated mandibular molar teeth. MATERIALS AND METHODS: The root canals of 120 extracted human mandibular molar teeth were prepared chemomechanically and obturated with laterally condensed cold gutta-percha. The crown of each tooth was sectioned leaving only one cusp standing. Gutta-percha was removed from the pulp chamber in all teeth. The volume of the pulp chamber was measured and the teeth ranked in ascending order of chamber volume. The specimens were divided into six groups of 20, allocating teeth with similar chamber volumes into each group. In three of the groups, gutta-percha was removed from the coronal 3-4 mm of each root canal. The teeth were restored with one of three materials, a cermet cement (Ketac-Silver), a resin-reinforced glass ionomer (Vitremer), or amalgam (Contour). Core preparation was carried out after 48 hours, reducing each core height to 6 mm. The specimens were thermocycled for 24 hours and then mounted in dental stone. A control group of 20 unrestored human mandibular molars was mounted in cold cure acrylic. Each tooth was tested in a Nene machine with a compressive load applied at 90 degrees to the occlusal surface at a crosshead speed of 5 mm/minute. RESULTS: There was no statistically significant difference between the experimental groups (P > 0.05), but the control group was significantly stronger (P < 0.001). Extension of core material into the coronal root canal system did not increase the fracture resistance of any of the experimental materials. Regression analysis of the results revealed no correlation between the volume of the pulp chamber and the load to fracture.     

Insulin effects on ouabain binding in A6 renal cells

OBJECTIVES: This study sought to identify risk markers associated with the provision of new restorations in children and to investigate whether the carious status of a tooth surface is associated with the restorative decisions of dentists. METHODS: A total of 911 schoolchildren in grades one, two, and three were randomly selected from the island of Montreal, Quebec, Canada. Dental examinations were carried out in 1990, 1991, and 1992. Tooth surfaces of first permanent molars were classified as sound, noncavitated, and cavitated. The carious status of a tooth was matched with restorative decisions reported to the insurance board. RESULTS: The presence of a carious cavity was a strong risk marker for placement of new restorations (odds rations > or = 4.11). After one year, less than 2 percent of sound tooth surfaces of first permanent molars were restored and about 21 percent of noncavitated tooth surfaces were restored. When new class I restorations placed in maxillary first permanent molars within 3-6 months after the baseline examination were evaluated, we found that between 73 percent and 86 percent of these new restorations were placed in sound or noncavitated tooth surfaces. A similar trend also was observed in mandibular first permanent molars. Poor agreement between epidemiologic diagnosis and restorative decisions was found. The restorative profile of dentists was a significant risk marker for placement of new restorations. CONCLUSION: The majority of new restorations in first permanent molars were placed in sound and noncavitated tooth surfaces because of the ubiquitous prevalence of these tooth surfaces and the validity problems of current caries diagnosis methods.     

Nerve degeneration within the dental pulp after segmental osteotomies in the baboon (Papio ursinus)

Following dentofacial surgical procedures, teeth in segments often do not sense thermal or electric stimuli. This study was undertaken to assess changes in the neural component of the dental pulp after posterior maxillary and mandibular segmental osteotomies, with or without interpositional autogenous bone grafting, in 26 Chacma baboons. Innervation was assessed histologically immediately after operation, and at 3, 6, 12 and 18 months. Statistically significant differences were present between the experimental and control groups. Even after 18 months no nerves were present in any of the mandibular teeth. In maxillary teeth, 50 per cent had demonstrable nerves in the graft group and 40 per cent in the no graft group. As nerve degeneration was present in the experimental teeth, patients should be warned of possible change in tooth sensibility, following these operations. Careful post-operative follow up for long periods in humans following dentofacial surgical procedures is thus essential.     

Effect of restored and unrestored non-carious cervical lesions on the fracture resistance of previously restored maxillary premolar teeth

OBJECTIVES: The effect of non-carious cervical lesions (NCCL) on tooth fracture resistance has not previously been investigated. The aims of this in vitro study were to examine the fracture resistance of a group of extracted maxillary premolar teeth with mesio-occlusal-distal (MOD) restorations of amalgam, and restored or unrestored simulated NCCL. METHOD: Forty sound maxillary, premolar teeth were divided at random into four groups, each of 10 teeth, which were fixed crown uppermost and long axis vertical in stainless steel moulds. Groups 1,2,3 and 4 were prepared with standardized parallel-sided MOD cavities, then restored with amalgam. Groups 1, 2 and 3 were further prepared with standardized NCCL. The NCCL in Group 1 were restored using a resin-modified polyalkenoate (glass-ionomer) cement, and the NCCL in Group 2 were restored with an adhesive composite resin system. The NCCL in Group 3 were left unrestored. The specimens were loaded compressively at 1 mm min-1 using a universal testing machine. RESULTS: Mean fracture loads (KN) of 1.08, 1.03, 0.98 and 1.14, respectively, were recorded for Groups 1, 2, 3 and 4. Two-way ANOVA and Scheffe's Multiple Range Test showed no statistically significant difference between the groups. CONCLUSIONS: It is concluded that the presence of a standardized NCCL in an extracted maxillary premolar tooth does not reduce the fracture resistance of the tooth when loaded compressively at 1 mm min-1. The restoration of NCCL with the materials tested did not result in an increase in the fracture resistance of the previously restored premolar teeth, when loaded compressively at 1 mm min-1.     

Variation in maxillary and mandibular molar and incisor vertical dimension in 12-year-old subjects with excess, normal, and short lower anterior face height

Maxillary and mandibular molar and incisor vertical dimensions were evaluated in subjects who had excessive, normal, and short lower anterior face height in relation to upper face height. Sexual dimorphism was also investigated. The dentoalveolar heights were compared between Class I and Class II, dental and skeletal malocclusions. The sample was drawn from the Burlington Growth Centre sample and consisted of 188 male and 156 female subjects at age 12 years, for whom lateral head films were available. This sample was classified into excessive, normal, and short lower anterior face height, using the ratio upper anterior face height/lower anterior face height (UAFH/LAFH). The results showed that the dentoalveolar heights are significantly different between faces with excessive, normal, and short lower anterior face heights, except for the lower posterior dental height, which showed no difference between short and normal lower anterior face height subjects. All dentoalveolar heights are larger for male subjects except for the upper posterior dental height. Dentoalveolar heights are similar between Class I and Class II dental and skeletal malocclusions. The upper teeth present a higher correlation to the UAFH/LAFH ratio than the lower teeth. Stepwise regression analysis shows that 22% of the variation in the ratio is explained by the maxillary and mandibular molars and 41% is explained by the maxillary and mandibular incisors.     

A new correction procedure for calibrating dental caries frequency

The incisors and canines and the premolars and molars show differential resistance to cariogenic factors. The anterior teeth have a lower caries frequency than the posterior teeth. However, these tooth classes are lost differentially in postmortem stages due to their anatomical structures. This differential postmortem tooth loss distorts proportions between the anterior and posterior tooth classes. The disproportionality can affect the calculation of total caries prevalence. In this paper, we propose a new calibration procedure which removes this disproportionality and call it the proportional correction factor. For this procedure, the caries rates of anterior and posterior teeth are corrected by multiplying the anterior teeth by three-eighths and the posterior teeth by five-eighths. These fractions are derived from the human dental formula which contains three anterior and five posterior teeth by side. The correction factor is more effective if the proportion of anterior to the posterior teeth is extremely distorted. When this procedure is used with the caries correction factor, it provides a useful way to approach to an almost true caries prevalence.     

Pleiotropic deficiencies of the laccase-derepressed mutant lah-1 are caused by constitutively increased expression of the cross-pathway control gene cpc-1 in Neurospora crassa

PURPOSE: To estimate gamma-ray doses received by Hiroshima atomic bomb survivors using electron spin resonance (ESR) of tooth enamel and to compare the results with cytogenetic data. MATERIALS AND METHODS: Tooth enamel ESR was performed for 100 teeth donated from 69 Hiroshima survivors, and conventional cytogenetic examinations were conducted for 61 of the tooth donors. To evaluate possible contamination from dental X-ray exposure, which primarily affects the tooth's buccal surface, each tooth was divided into buccal and lingual parts for subsequent independent enamel isolation and ESR measurement. RESULTS: Almost 20 teeth showed considerably larger buccal doses than lingual doses, but most of these discrepant teeth were incisors and canines. The results are probably attributable to solar light exposure. In contrast, the buccal and lingual doses found in molars were similar. Conventional translocation data of lymphocytes and ESR-estimated doses of 40 donors of molars showed the dose-response for translocations to be almost the same as that expected from in vitro gamma-ray irradiation experiments. CONCLUSIONS: Both tooth enamel ESR and lymphocyte cytogenetics are useful measures for individual biodosimetry of acute radiation exposure, even half a century after the exposure occurred.     

Reattachment of coronal fragments: operative considerations for the repair of anterior teeth

The maxillary incisors occupy an extraordinary position in the dental arch. They set the aesthetic tone, and their influence on the overall well-being of the individual cannot be overemphasized. However, their eruptive pattern and dominance carries a significant risk for trauma, particularly in childhood. More than half of all traumatic dental injuries involve the central incisors. In the past, fractured teeth were either extracted, trimmed and leveled, or restored with cast restorations. The learning objective of this article is to stimulate a shift in treatment strategy towards aesthetic reattachment of fractured segments. Indications and limitations for reattachment are outlined, including the primary and secondary restorative efforts. Innovative operative techniques that improve the aesthetic, biologic, and mechanical variables of the reattachment treatment option are presented.     

Sexual transmission of GB virus C/hepatitis G virus

Tooth transposition is a positional interchange of two adjacent teeth. The most commonly transposed tooth is the permanent canine with either the first premolar or lateral incisor. The records of 54 subjects with transposed canines, both maxillary and mandibular, were collected. Pretreatment study models of these subjects were matched with a similar number of models from unaffected individuals. Bucco-lingual and mesio-distal tooth widths, arch depth and arch width were measured on each model. Thirty-four subjects (63 per cent) were female. Thirty-seven (68.5 per cent) of the cases involved the maxillary arch and thirty-three (89.2 per cent) of these upper arch transpositions were of the canine and first premolar. In cases involving the lower arch the canine was invariably transposed with the lateral incisor. Peg-shaped lateral incisors, supernumerary and/or congenitally absent teeth occurred in 19 subjects. There were some small, but significant differences in the dimensions of some teeth, however there were no statistically significant differences in arch depths, arch widths and most tooth dimensions in subjects with and without transposed canines. These factors do not appear to be related to the development of canine transposition.     

Peer approaches for increasing HIV awareness on a college campus

PURPOSE: To compare the accuracy of clinical examination performed with bitewing radiographs or clinical examination using tooth separation to identify carious lesion activity. MATERIALS AND METHODS: 320 surfaces from 40 bitewing radiographs were examined for approximal caries on the maxillary and mandibular primary molars of 20 patients 3-10 years old. The patients were divided into three groups: (1) Absence of the permanent first molar; (2) Partial eruption of the permanent first molar; and (3) Full eruption of the permanent first molar. Two examiners evaluated the radiographs using a megascope, a magnifying glass (x2), and an amplifying image screen. Approximal radiolucencies were identified on 72 surfaces. Following the radiographic examinations, the two examiners performed conventional clinical inspection using a No. 4 dental mirror, a No. 5 dental explorer, and an air-water syringe, with artificial light and relative isolation. The separation method was performed with elastic bands, which were removed after 24 hours, and the clinical examination conducted as in the non-separation group. RESULTS: The correlation between the extension of interproximal radiolucent lesions in primary dentition and their clinical diagnoses following separation of the teeth, was similar to findings on literature evaluating the permanent dentition. On radiographic findings for enamel lesions, white spots predominated both in the inner (100%) and in the outer (94%) half of enamel upon clinical examination with separation of teeth. For radiolucent lesions in dentin, on the other hand, cavities predominated over white spot lesions (84%). In Groups 1 and 2 (young primary), white spots occurred in cases where the radiolucent lesions reached the dentin (15% and 25%), similar to findings for young permanent teeth. Clinical diagnosis performed with the mechanical separation of teeth cannot be considered conclusive for the primary dentition.     

Dens evaginatus from an orthodontic perspective: report of several clinical cases and review of the literature

The anomaly of dens evaginatus manifests itself as an innocuous-looking tubercle of enamel on the occlusal surface of a premolar tooth. Problems can arise when the tubercle is either worn, ground, or fractured off, resulting in pulpal exposure and possible loss of vitality of the tooth. Orthodontists should be particularly aware of this dental anomaly, which occurs in at least 2% of the Asian and Native Indian population. Premolar extraction cases should be planned to include extraction of the anomalous premolars instead of the normal ones. In addition, the orthodontist should be wary of occlusal changes during treatment or occlusal equilibration that might jeopardize the vitality of teeth with dens evaginatus. Pulp-capping or partial pulpotomy has been postulated as the most reliable form of treatment to prevent loss of vitality of the affected teeth and to allow continued root maturation where necessary.     

Definitive injuries to the teeth. Lesions of hard tissue and pulp

Tooth infraction and enamel fracture are the most simple traumatic crown lesions. When necessary the lesions can be covered with composite material. Follow-up of the traumatized tooth is necessary since pulp necrosis and obliteration can develop. In case of an uncomplicated fracture involving enamel and dentine immediate protection of the dentinal wound is important for the preservation of tooth vitality. In case of a negative vitality test, an endodontic treatment will be performed in case of a tooth with open apex only when supplemental clinical and or radiological signs of pulp necrosis are present. When a complicated enamel-dentine fracture is present, an endodontic treatment will be performed when root formation is complete. In case of a wide open apex, a pulp capping, partial pulpotomy or cervical pulpotomy will be performed in order to preserve vitality of pulpal tissues at the level of the root. Crown root fractures can be superficial, deep or vertical. In case of a superficial localisation of the fracture line, restoration with composite material or with the fractured tooth segment is indicated. Deep crown-root fractures can only be restored when the fracture line is localized not deeper than at 1/3 of the length of the root. In case of a vertical fracture, extraction is the only possibility. Root fractures on immature teeth are in most cases unilateral and have a good prognosis. In teeth with completed root formation, fractures at the level of the cervix have a poor prognosis. The fractured segment will be removed. Only when the remaining root segment is long enough, this part can be maintained. In case of a fracture at the mid-root level, repositioning and rigid splinting for a period of 8 weeks is necessary. When the tooth becomes non-vital, endodontic treatment is performed on the coronal part. Root fracture in the apical part does not necessary result in enhanced tooth mobility and immobilisation is not always necessary. Healing of a root fracture is only possible when the tooth is immobilized for a sufficiently long period. Regular control of tooth vitality is necessary since pulp necrosis can lead to an inflammatory reaction at the level of the fracture line.     

Mandibular fractures: the problem patient

Of 110 adult patients with 163 mandibular fractures treated at University of Pennsylvania Graduate Hospital from 1964 to 1974, 17% had a history of previous mandibular fractures. All patients' medical records and X-rays were reviewed. Because of the characteristics of this patient population, it seems well suited for discussion as a problem group. Mandibular fractures in this urban area are most commonly caused by blows of a fist and the patient is often intoxicated, which impedes diagnosis, delays treatment, and probably results in further complications from injuries. Patients frequently do not comply with treatment recommendations, do discontinue immobilization, and fail to return for followup, even for removal of intermaxillary fixation. Almost one third had insufficient teeth for fixation; many had poor oral hygiene, and teeth in the fracture line, which led to complications. Osteomyelitis resulting in nonunion and requiring bone grafting occurred in seven patients. Recommended are: simplest fixation methods, minimal amounts of surgery, and as few extractions as possible. Experience from this patient group may be of help whenever a problem patient is seen with a mandibular fracture.     

Treatment of root fracture by CO2 and Nd:YAG lasers: an in vitro study

The purpose of this in vitro study was to use scanning electron microscopy and polarized light microscopy to evaluate the feasibility of using either the CO2 laser or an Nd:YAG laser in combination with air/water surface cooling to effect fusion of fractured tooth roots. The experimental unit consisted of 81 single-rooted teeth, each with an induced root fracture. Fifty-six teeth that had been reapproximated in dental stone and 25 teeth that had been reapproximated with C-clamps were assigned to untreated control groups or groups for treatment using CO2 and Nd:YAG lasers. Laser treatment consisted of multiple passes along the line of fracture, which was inspected using a dissecting microscope after each pass until a visual indication of fusion or irreparable damage resulted. Scanning electron microscopy evaluation of the treated lines revealed heat-induced fissures and cracks, areas of cementum meltdown and resolidification, crater formation, and separation of cementum from underlying dentin. In no instance-regardless of reapproximation technique, laser type, energy, and other parameters-did the treatment effect fusion of the fractured root halves.     

2-year clinical evaluation of a gallium restorative alloy

PURPOSE: To assess the clinical performance of 2-year old gallium alloy restorations. Parameters evaluated include: (1) fracture at the margins, (2) tarnish, (3) surface roughness, (4) tooth fracture, (5) fracture through the body of the restoration, and (6) any medical or dental conditions arising during the study. MATERIALS AND METHODS: Nine patients received 30 Class I restorations of Galloy gallium alloy. These were placed as conservatively as possible under a rubber dam. Fifteen of the preparations were lined with a Bis-GMA resin to seal the restoration from moisture. The other 15 preparations were sealed with Amalgambond. After placement of the gallium alloy, the exposed surfaces of all restorations were sealed with the Bis-GMA resin, and the occlusion was checked. The restorations were examined at 2 weeks, 3 months, 6 months, 1 year and 2 years. RESULTS: At the 2-year recall, all restorations were intact with the exception of one tooth fracture (cause unknown). Forty-five percent of the restorations exhibited tarnish and 60% had a rough surface. The fracture at the margins of these restorations was minimal, and no significant difference could be found between those using Amalgambond and those sealed with the resin system. No medical problems were reported by the patients, and postoperative sensitivity was minimal.