Frühzeitiger Zahnverlust nach Leukämiebehandlung im Kindesalter

BACKGROUND: Only few reports of effects of radiotherapy in childhood on the dental apparatus are available in the literature. The basis for early loss of teeth appears to be a reduction of the root surface area after radiation exposure. These effects in the periodontium are a consequence of combined radiochemotherapy usually applied for treatment of childhood neoplasia. Chemotherapy alone also results in changes of periodontal development. CASE REPORT: A 33-year-old patient is reported, who, at the age of 11 years, received high-dose chemotherapy and radiotherapy of neuroaxis and cranium for acute lymphatic leukemia with relapse. The patient consulted the Implant Section of the Department of Oral and Maxillofacial Surgery because of severe dental changes and tooth loss despite adequate dental care and oral hygiene. Radiation doses given to the superior maxilla and mandible at the age of 11 were estimated to be in the range of 8-25 Gy. CONCLUSION: Intense, life-long dental care and follow-up of patients cured from malignant disease in childhood must hence be postulated in order to minimize dental treatment sequelae by supportive measures, but also to initiate timely adequate dental and prosthetic management.     

Visibility of dental pulp spaces in dental ultrasound

The purpose of this study was to assess the feasibility of dental ultrasound with conventional sonographic equipment. The teeth of three adult volunteers who had cone beam CT examinations performed previously with clinical indications and one extracted tooth were examined using linear and compact (hockey stick) sonographic probes. The sonographic images were compared with cone beam CT images reconstructed accordingly. Dental pulp spaces were demonstrated in all teeth not covered with prosthetic crowns. The dentin and pulp were best visualized at the level of the neck of the teeth. The dentin was hypoechoic, and the superficial layer comprising the cementum and the pulp spaces were hyperechoic. Dental ultrasound is feasible with general purpose sonographic machines. The buccal surfaces of all teeth are accessible with a compact (hockey stick) probe. Visualization and differentiation of dental pulp spaces, dentin and the superficial layer comprising cementum is possible in the portions of teeth not covered by the alveolar bone or prosthetic crowns. The dental pulp spaces are best seen at the level of the tooth neck. Pulp and endodontic fillings can be distinguished on ultrasound.     

Dentine and cementum as sources of nuclear DNA for use in human identification

Teeth are increasingly utilized as a source of nuclear DNA to aid identification of human remains. DNA extraction and the results of genetic analysis from these tissues are extremely variable and to some extent unpredictable. This study examines the availability of nuclear DNA in different areas of the dental hard tissues and explores the extent and nature of the variation within and between individuals. Results of this study indicate that nuclear DNA is available in widely variable quantities in dentine and cementum. This variation exists within teeth and between teeth, even between comparable teeth from the same individual. The quantity of DNA available in dentine is affected by age and dental disease, whereas that in cementum is not. Forensically useful genetic profiles were obtained from as little as 20 mg of tooth powder, thus avoiding the necessity for complete destruction of the tooth. A better understanding of why there is more DNA in one tooth tissue or region compared with another, and of the effects of disease and age, will aid in the selection of which tooth and tissue to sample and will increase the validity of the use of teeth as a source of nuclear DNA for human identification.     

Dental fractures on acute exposure to high altitude

There is little in the literature on dental restoration breakage in the aviation environment since reports of problems in combat aviators in War World II. We report two cases of dental fractures during acute exposure to a hypobaric environment. Case 1 was a young officer who suffered an amalgam restoration breakage during a 25,000-ft decompression chamber simulation. Case 2 occurred in an experienced aviator who had a tooth cusp fracture in a molar with a defective amalgam restoration during an unpressurized helicopter flight to 18,000 ft. In both cases, after removing the defective fillings, deep secondary caries were found; both teeth were successfully restored. Because hard-tissue tooth fracture during a high-altitude flight is a rare event, few flight surgeons or dentists are familiar with this phenomenon. We recommend regular dental examinations with careful assessment of previous dental restorations in aircrew subject to decompression.     

Dental injuries in sports

The expanding arena of sports and vigorous recreational activities is associated with an increased risk for sportsrelated injuries, including trauma to the teeth. Because dental professionals may not be present on site, in the best interest of athletes, it is suggested that sports medicine professionals who are present be provided with current evaluative, emergent, and referral protocols for proper management of sports-related dental injuries to address the immediate needs of the athlete and to enhance the long-term prognosis of the traumatized tooth. This article provides information related to some of the more common dental injuries encountered in sports, including crown fractures, root fractures, and traumatic tooth displacements. Use of properly fitted, custom-fabricated athletic mouth guards for the prevention of dental injuries is recommended strongly, as is the inclusion of a dentist on the sports medicine team roster.     

Osteoradionecrosis. I. Etiology, pathogenesis, clinical aspects and risk factors

In curative therapy of mouth-cavity and oropharyngeal carcinomas the osteoradionecrosis has to be accepted as a calculated risk with an incidence of 4-35%. It is the question of a radio-caused bone death that comes about by progressive and irreversible morphological alterations at bones and at vessels: Loss of osteocytes, active osteoblasts and osteoclasts (hypocellularity), injury of normal bone metabolism, slackening of regeneration process, extreme susceptibility to infections of the devitalized bone, radio-induced obliterating endarteritis with hyalinization, thrombosis and fibrosing of vessels, obliteration of the lumen and gradual reduction of blood-supply at the level of tissue (hypovascularity and hypoxemia: Aseptic osteoradionecrosis, radio-osteonecrosis). If there is a secondary infection of dental, periodontal or traumatic origin additionally, the condition explodes as septic osteoradionecrosis with the symptoms and findings of radio-osteomyelitis. The osteoradionecrosis begins more frequently in the mandibula than in the maxilla. The cumulative incidence is 30% after 6, 60% after 12, and more than 80% after 24 months. The duration of osteoradionecrosis follows an exponential curve with constant probability of necrosis termination at any moment after necrosis event in which the monthly probability of necrosis healing is nearly 0.06. Risk factors for formation of an osteoradionecrosis are tumor neighbourhood to bones and teeth, tumor and mandibula dosis, tumor stage, irradiation technique, status of teeth as well as moment and carrying out of tooth extractions. Tumors in neighbourhood of mandibula have a fivefold higher risk, with 80 Gy irradiated patients a 2.9-fold and toothed patients a 2.6-fold, altogether high-risk patients have a 17.7-fold higher necrosis risk than low-risk patients. Promoting factors are caries, parodontosis, a periapical pathology, a trauma, irritation by artificial teeth, elective tooth extraction before irradiation, tooth extraction after irradiation as well as jaw operations because of remains or recurrence of the tumor.     

Periodontal dentistry

Diagnostic radiographs are an invaluable aid to the diagnosis, treatment and monitoring of periodontal disease. However, their usefulness depends very much on minimised distortion of bone and tooth tissue images in an area of the body where the dental radiographer's knowledge, both of the local anatomy and the needs of the clinician, make a tremendous difference. In conclusion, radiographic bite-wings are the most accurate projections to demonstrate periodontal disease of the bone margins relative to the necks of the teeth. However, the roots of the teeth are not demonstrated. The OPG gives the best overall picture of the whole mouth and the film can be shown and explained to the patient. Paralleling projections may be still needed in certain areas of the mouth where greater detail is required. Some periodontologists still prefer full mouth paralleling films for their patients.     

涡轮机分牙法与去骨法拔除男性下颌阻生第三磨牙的对比

 目的 比较涡轮机分牙法与去骨法对下颌阻生第三磨牙拔除术后反应的差异,为这类患牙的拔除方式选择提供参考。方法 选择门诊患者68位,共82颗患牙,随机分为两组,一组采用分牙法,另一组采用去骨法,每组41颗患牙。分牙法组使用涡轮机分牙法拔除患牙;去骨法组使用涡轮机去骨法拔除患牙。比较两组手术时间、术后疼痛、面部肿胀及张口受限程度的情况。结果 分牙法组手术时间为(23.5±6.4)min, 而去骨法组手术时间为(16.5±3.3)min,两组差异有统计学意义(P＜0.01);分牙法组术后疼痛及术后肿胀方面症状均轻于去骨法组,差别有统计学意义(P＜0.01);术后张口受限方面分牙法组和去骨法组比较,无统计学差别。结论 两种方法各有利弊,涡轮机分牙法可明显减轻术后疼痛和肿胀症状,但手术时间较长。     

Tooth shape reconstruction from dental CT images with the region-growing method

Objectives:

The three-dimensional shape information of teeth provides useful information. However, obtaining accurate three-dimensional shapes of teeth is difficult without extracting them physically. In this study, we aimed to develop a method for automatically extracting accurate three-dimensional shapes of teeth from dental CT images.

Methods:

The proposed method includes pre-processing and region extraction. Pre-processing is a combination of image-processing techniques that enhances tooth regions. In the region-extraction process, the region-growing method is introduced for extracting a region of each tooth. Constraint conditions determined by considering the characteristics of the structure of teeth are introduced for accurate extraction. Finally, morphological image processing is applied for eliminating discontinuous points.

Results:

We carried out an experiment in which the three-dimensional shapes of teeth were reconstructed from dental CT images. Quantitative evaluation was performed by measuring the three-dimensional spatial accordance rates between the region obtained by the proposed method and the manually extracted region. The proposed method was significantly more accurate than an existing method at the 5% level.

Conclusions:

The experimental results showed that the proposed method reconstructs the shapes of teeth with high precision. However, an unextracted region remained at the surface of the enamel. Solving this problem and improving the extraction accuracy are important topics for future work.     

Age assessment at the time of death based on panoramic radiography

BACKGROUND: The determination of age at the time of death is an important method in forensic anthropology and paleodemography. The possible postmortem investigation of the teeth and jaws enables the determination of age at the time of death, as the bones and teeth are both resistant to degradation in soil and characterized by age-related morphological changes. The aim of this study was to determine whether the age-related changes visible on panoramic radiography correlated with age, and enabled the assessment of individual age. METHODS: Seven radiographic parameters were used in the study: tooth loss, occlusal tooth wear, pulp stones, carious teeth, periapical disease, tooth restoration, and alveolar bone loss associated with periodontal disease. RESULTS: The material comprised 314 dental panoramic tomograms of living patients of both sexes with documented age (18 to 77 years). Multiple regression equations were constructed for the age estimation, including four parameters (the number of missing teeth, the number of intact teeth, the distance of cement-enamel junction from the alveolar ridge, the number of abraded teeth). The nature of data treated by regression analysis required the careful choice of parameters, appropriate functional model for each parameter, and the experience of the investigator. With the four parameters included in equations, the error was +/- 2.55 years. CONCLUSION: This preliminary analysis showed that the conventional regression technique could be appropriate for the age estimation based on panoramic radiography, and that an additional study with a larger sample and on wider population was required.     

Die Zuordungswahrscheinlichkeit eines numerisch-topographischen Zahnstatus bei der Identifikation unbekannter Leichen

The numerical topographical dental findings of 29,862 adult patients from several German dental practices were evaluated. Taking into account the age-dependent loos of teeth the various decades were investigated separately for increased incidences of identical findings. The total number of teeth comprising the dental findings in the form of tooth number classes was a first-line criterion aiding classification. In accordance with an underlying binominal distribution, a raised incidence of identical dental findings was found both in patients edentulous jaws or few residual teeth and in patients with largly complete dentition. The raised incidence was confined to a few standard findings in each of these high or low tooth number classes. However, more than 50% of all cases were either in the intermediate tooth number classes, in which raised incidences of ≥ 0.2% generally do not occur, or showed correspondingly rare constellations of findings in the high or low tooth number classes. In more than half of all cases, there was therefore a numerical topographical dental status which can be used in identification with a matching probability of ≥ 99.8%. Dental findings which occur less frequently can be arranged clearly according to tooth number classes.     

Eruption times of permanent teeth in teenage boys and girls in Izmir (Turkey)

In a study in the Aegean city of Izmir, Turkey, during the summer of 2002, 2101 patients (1046 boys and 1055 girls) were examined. The examination occurred within the framework of a dental check-up performed at two schools and one pre-school unit. The age span ranged from 3.98 to 24.91 years. Sex, age and present permanent teeth were recorded. Wisdom teeth were excluded. The sequence of tooth eruptions differs significantly in the lower and upper jaw, whereas no significant differences existed when comparing the sides of each jaw. The times of tooth eruption is earlier in females than in males. The entire tooth eruption process of the second dentition occurs in females earlier than in males. The tooth eruption in the lower and upper jaw of male and female probands is symmetrical. In comparing the upper and the lower jaw of both genders, it becomes evident that there is a tendency for earlier tooth eruptions in the lower jaw. In respect to the tooth eruption sequence, a change was noted in the upper jaw. Contrary to the reports of other authors, the second premolar has changed places with the canine and erupts prior to this tooth. Otherwise no major differences concerning the sequence of tooth eruptions, when compared to the results gained from other populations, were observed. Concerning the entire dentition, no acceleration of the tooth eruption could be noted. The computed differences of teeth eruption as a mean value calculated over all teeth, was +/- 1 year at maximum, compared to studies from different continents. Oral examination of teeth is a simple tool to calculate tooth eruption intervals. This first investigation on a population of Izmir revealed a change in the eruption sequence of permanent teeth. These findings are relevant for dental treatment planning and forensic odontology and should be reconfirmed at certain intervals.     

Neue Erkenntnisse zur Ätiologie der sogenannten Strahlenkaries

Aim

In spite of a great number of relevant studies the etiology of radiation induced caries still is discussed in controversy: The assumption of direct radiation induced lesions in the hard tissue is in contrast to an indirect pathogenesis mediated via radio-xerostomia.

Methods

A systematic study is presented, comparing teeth with a manifest radiation caries (group 1, about 60 Gy, long interval to the extraction) and clinically caries free teeth (group 2, about 30 Gy, short interval) with tooth specimens after an experimental enoral (in situ) irradiation (60 Gy, group 3) and after in vitro irradiation (500 to 2.500 Gy, group 4).⁶⁰Co was the irradiation source. Sound teeth were used as a standard (group 5). For non destructive visualisation of subsurface histotomograms by confocal laser scanning microscopy (CLSM) teeth were either used as fresh sections or as Technovit embedded thin slices (sawing grinding technique).

Results

Tooth samples from radiotherapy patients (cancer therapeutic doses, long interval before extraction; group 1) showed three characteristic changes: 1. rarefication of the branching (ramification) of odontoblast processes near the junction, 2. dentine tubules end infront of the interface to the hard tissue and 3. in dentine the interface is characterised by an zone (about 10 μm wide) of low intensity of the remitted light.

Conclusions

The obliteration of the dentine tubules, preceded by a degeneration of the odontoblast processes, is obviously the result of a direct radiogenic cell damage with hampered vascularisation and metabolism particularly in the area of the terminations of the odontoblast processes. The deficit in metabolism combined with a latent damage of the parenchyma (hypo-remitting zone) is evidence for the functional symptoms (subsurface caries). The prerequisite for the micromorphological manifestation of this direct irradiation damage is a vital tooth and in consequence cannot be simulated in situ or in vivo.     

A non-syndrome case with bilateral supernumerary canines: report of a rare case

Supernumerary teeth are described as the teeth formed in excess of the normal dental formula. Prevalence of supernumerary teeth varies between 0.1% and 3.8% in general Caucasian population. They have been reported in both the primary and the permanent dentition. Supernumerary teeth may occur in any region of the dental arch. However, a supernumerary tooth in the canine region is a rare condition and to our knowledge, a non-syndrome case with bilateral supplemental maxillary canines did not exist in the literature. It was the aim of this report to evaluate this rare case in view of both oral radiology and orthodontics.     

Evaluation of intraoral CCD camera for dental examination in forensic inspection

This study was performed to assess the effectiveness of an intraoral CCD camera for dental examinations when sufficient jaw opening or adequate lighting cannot be obtained. A handpiece-type intraoral CCD camera (Crystal Cam; GC Corp., Japan) was used for the study. Because a full view taken by the intraoral CCD camera covers only one or two teeth, all the teeth were individually photographed and a view of the dentition assembled on a personal computer. Assuming that the jaw could not be opened widely enough to inspect an occlusal view, a dry skull and a volunteer were restricted to open the mouth and all the teeth were photographed with an intraoral CCD camera. These were compared to intraoral photographs taken by the conventional method using a single-lens reflex camera and mirror. When the intraoral CCD camera was used to photograph teeth, the color tone of metal restorations could be readily identified, but special care was required to identify carious lesions, discoloration of tooth structure, and esthetic restorations. The dentition photographs assembled from the original intraoral CCD images were transferred via the Internet as e-mail attachment files to allow preparation of the dental chart at the destination. Based on the transferred images, it was possible to prepare a dental chart agreeing satisfactorily with actual oral conditions. The easy transfer of digital images provides various advantages in evaluating and discussing certain cases in cooperation with other forensic odontologists via the Internet. The camera may be made more effective or useful through improvement of the tip portion of the camera and the entire system to achieve a more compact design and better portability.     

改良式固定型马里兰桥修复老年前牙缺失的临床效果观察

目的 探讨运用改良式固定型马里兰桥修复老年患者前牙缺失的可行性,并对修复的方法设计、修复体制作过程及适应证进行总结.方法 选择个别前牙缺失,存在不同程度邻牙松动、牙龈萎缩、牙根暴露等体征的老年患者24例,运用改良式固定型马里兰桥修复缺失牙,并对完成修复的病例随访3～5年.结果 修复成功率为87.5%.24例患者有3例修复体脱落,需重新粘接;其余修复体未见明显松动.基牙无松动,桥体下方牙龈无明显红肿,患者对修复体的使用与外观效果均感满意.12例患者存在不同程度牙结石;2例患者存在舌侧轻度异物感,经过对症处理后效果满意.结论 改良式固定型马里兰桥修复老年前牙缺失具有磨牙少、效果美观,并能同时固定松动牙邻牙等优点,修复效果可靠.但其远期效果有待进一步观察.     

Migrating third molar: a report of a case

Pathologic migration is an abnormal change in the position of a tooth within the dental arch. There are many etiologic factors associated with this phenomenon, but the exact cause is often difficult to diagnose. The following is a report of a 42-year-old man exhibiting a unique form of bilateral migration of his mandibular third molars. He was asymptomatic and unaware of this occurrence. The morbidity to remove these teeth was deemed too great to justify extraction. Biopsy of the overlying tissue associated with a left-impacted third molar revealed no significant pathologic process other than inflammation and some hyperplasia within the dental follicle. Histologic-radiographic correlation was inconclusive in determining whether epithelium from pericoronal soft tissue involving the right third molar was from a hyperplastic dental follicle or a small dentigerous cyst. It is speculated that the ultimate cause of the migration of the third molars was severe, aggressive periodontal disease of the adjacent molars.     

航海人员洁治术对干槽症的影响及原因分析

目的　探讨干槽症发病的相关因素和预防航海人员干槽症发生的方法。方法　对 4 6 8例需要拔除双侧下颌阻生智齿的航海人员在无拔牙禁忌证的情况下分次进行拔牙手术 (相隔时间 2个月以上 )。第 1次拔牙前不进行特殊术前准备 ,第 2次术前进行全口龈上下洁治术 ,术后 3～ 5 d拔牙。 2次拔牙前均牙菌斑取样检测幽门螺杆菌 (Helicobacter pylori,H.Pylori)。结果　第 1次拔牙后 78颗发生干槽症 ,占 16 .6 7% ;第 2次拔牙后仅 9颗发生干槽症 ,占 1.92 % ,差异非常显著 (P<0 .0 1)。牙菌斑 H.py-lori检测结果 2次拔牙前阳性率分别为 5 4 .2 7% (2 5 4 / 4 6 8)和 14 .74 % (6 9/ 4 6 8) ,差异亦有显著性 (P<0 .0 5 ) ,且所有发生干槽症的手术拔牙前牙菌斑 H.Pylori检测均为阳性。结论　口腔幽门螺杆菌感染可能是航海人员干槽症发病率高的原因 ,术前口腔洁治可以有效预防拔牙术后干槽症的发生。