CAD/CAM ceramic restorations in the operatory and laboratory

Computer assisted design/computer assisted machining (CAD/CAM) technology has received considerable clinical and research interest from modern dental practices as a means of delivering all-ceramic restorations. The CEREC, System offers CAD/CAM dental technology designed for clinical use by dentists, as well as a separate system designed for dental laboratory technicians. The CEREC 3 system is indicated for dental operatory applications, and the CEREC inLab, system is indicated for dental laboratory applications. Although both systems rely on similar CAD/CAM technology, several significant differences exist in the processing techniques involved, restorative materials used, and types of restoration provided.

Prospects for tooth regeneration in the 21st century: a perspective

The prospects for tooth regeneration in the 21st century are compelling. Using the foundations of experimental embryology, developmental and molecular biology, the principles of biomimetics (the mimicking of biological processes), tooth regeneration is becoming a realistic possibility within the next few decades. The cellular, molecular, and developmental "rules" for tooth morphogenesis are rapidly being discovered. The knowledge gained from adult stem cell biology, especially associated with dentin, cartilage, and bone tissue regeneration, provides additional opportunities for eventual tooth organogenesis. The centuries of tooth development using xenotransplantation, allotransplantation, and autotransplantation have resulted in many important insights that can enhance tooth regeneration. In considering the future, several lines of evidence need to be considered: (1) enamel organ epithelia and dental papilla mesenchyme tissues contain stem cells during postnatal stages of life; (2) late cap stage and bell stage tooth organs contain stem cells; (3) odontogenic adult stem cells respond to mechanical as well as chemical "signals"; (4) presumably adult bone marrow as well as dental pulp tissues contain "odontogenic" stem cells; and (5) epithelial-mesenchymal interactions are pre-requisite for tooth regeneration. The authors express "guarded enthusiasm," yet there should be little doubt that adult stem cell-mediated tooth regeneration will be realized in the not too distant future. The prospects for tooth regeneration could be realized in the next few decades and could be rapidly utilized to improve the quality of human life in many nations around the world.

Oral healthcare of clients with learning disability: changes following relocation from hospital to community

OBJECTIVE

To investigate changes in the oral healthcare of adults with learning disability after transference from long stay hospital care to community-based care.

SUBJECTS

Adults with learning disability who were former residents of a single long stay hospital and who had been resettled into the community during the period April 1995 to April 1998.

DESIGN

Structured questionnaire with a covering letter sent to community-based carers. Hospital notes were reviewed to assess oral healthcare received as in-patients.

RESULTS

There was a 68% response rate to the questionnaire from community-based carers with details obtained from 106 out of a possible 157 subjects. As residents in the hospital, all subjects were examined regularly by a dentist--yearly for edentulous and six-monthly for dentate individuals. However, attendance patterns were less regular as residents in the community. In the community, individuals were also less likely to receive operative dental treatment. Although oral hygiene regimes were generally on a daily basis only 37% of the subjects and/or their carers had received oral health education from dental professionals in the community.

CONCLUSION

Changes from institutional living to community-based housing for adults with learning disability may be associated with changes in dental attendance and treatment patterns.

[Subcutaneous emphysema and pneumomediastinum after dental drilling]

Subcutaneous emphysema and pneumomediastinum is a rare complication of dental treatment. Our case report describes a case secondary to dental drilling with a high-speed air drill, and diffusion of the compressed air. Our case had the classical clinical features of sudden subcutaneous emphysema starting in the face, and subsequently extending into the neck and thorax, accompanied by severe pain and dyspnoea. Rapid medical treatment for this emergency avoided the surgical decompression.

Removal of dental amalgam and other metal alloys supported by antioxidant therapy alleviates symptoms and improves quality of life in patients with amalgam-associated ill health

OBJECTIVES

The purpose of this study was to evaluate treatment of patients suffering from chronic ill health with a multitude of symptoms associated with metal exposure from dental amalgam and other metal alloys.

SETTING AND DESIGN

We included 796 patients in a retrospective study using a questionnaire about symptom changes, changes in quality of life as a consequence of treatment and assessment of care taking.

METHODS

Treatment of the patients by removal of offending dental metals and concomitant antioxidant therapy was implemented according to the Uppsala model based on a close co-operation between physicians and dentists.

RESULTS

More than 70% of the responders, remaining after exclusion of those who had not begun or completed removal, reported substantial recovery and increased quality of life. Comparison with similar studies showed accordance of the main results. Plasma concentrations of mercury before and after treatment supported the metal exposure to be causative for the ill health.

MAIN FINDINGS

Treatment according to the Uppsala model proved to be adequate for more than 70% of the patients. Patients with a high probability to respond successfully to current therapy might be detected by symptom profiles before treatment.

CONCLUSIONS

The hypothesis that metal exposure from dental amalgam can cause ill health in a susceptible part of the exposed population was supported. Further research is warranted to develop laboratory tests to support identification of the group of patients responding to current therapy as well as to find out causes of problems in the group with no or negative results.

[Not Available]

The present study deals with the reconstruction of the mandible on jaw and face injured soldiers in the First World War. The central element of the reconstruction - the bone transplantation - is described on various treatment methods carried out by 66 european surgeons and dentists. The main part of the study shows which kind of material and which operation technique they used and the results they achieved. The end of the study points out the importance of the bone transplantation concept used between 1914 and 1918. By the year 1914, no concept existed for the reconstruction of destroyed mandible. Only through the First World War experience did the free bone transplantation become the best concept of repairing the lower jaw. Shortly after the beginning of the war, the surgeons roughly knew how to get a solid result. Nevertheless, the operators did not fully understand why bone healing could sometimes be established and sometimes not. Only Carl Partsch from Germany assumed that the fracture healing depended on the tight contact between undamaged surfaces of stumps and transplantation pieces.

Investigation of potential iatrogenic transmission of hepatitis C in Victoria, Australia

OBJECTIVE

To determine the level of exposure to medical and surgical procedures among Australian-born patients whose mode of acquisition of the hepatitis C virus (HCV) is unknown.

METHOD

Place and time of study: Melbourne, Australia, 1998-2000.

DESIGN

Retrospective case series.

INSTRUMENT

Structured questionnaire administered by one interviewer.

SETTING

Referral centre for hepatitis C in a tertiary teaching hospital.

PARTICIPANTS

Australian-born individuals persistently HCV antibody (anti-HCV) positive on at least two second-generation commercial assays.

MAIN OUTCOME MEASURES

Demographic and self-reported exposure data.

RESULTS

Of 135 anti-HCV positive individuals with no known mode of transmission, 54 (40%) individuals fulfilled all the entry criteria and agreed to participate. Of the 54 cases, 53 had at least one medical/surgical procedure and/or invasive dental work; 46 (85%) had dental extractions, 19 (35.2%) had complex dental work, e.g. root canal, 44 (82%) had an operation requiring general anaesthesia, 41 (75.9%) had a procedure requiring local anaesthetic, and a number of endoscopic procedures were reported: gastroscopy (n=3), colonoscopy (n=3), laparoscopy (n=4), arthroscopy (n=5), cystoscopy (n=2).

CONCLUSION

We have documented exposure to medica/surgical procedures among HCV patients with no previously recognised mode of transmission.

IMPLICATIONS

The findings of this study have important public health implications for current cleaning, disinfection and sterilisation procedures and protocols (or lack of these) as well as for the policies and guidelines relating to the re-use of medical equipment such as multi-dose vials, suturing material and anaesthetic circuits.

An update on the physiology of the dentine-pulp complex

The properties of dentine and pulp are closely related and from a functional standpoint these tissues are often referred to as the dentine-pulp complex. In recent years there has been considerable progress in our understanding of the physiology of the dentine-pulp complex. This review describes some of the advances that are relevant to clinical dentistry, including dentine permeability, dentine bonding, dentine sensitivity, the properties of pulpal nerves and blood vessels and the reactions of the dentine-pulp complex to operative dental procedures.

It's time to revive dental study clubs

Dental study clubs provide a major opportunity for dentists to meet with other dentists and dental team members and to learn in a friendly, nonthreatening environment. They afford members the opportunity to increase their knowledge of and clinical skills in using new concepts, materials, techniques and devices by hearing about them from fellow members or by working with and evaluating innovations themselves for the benefit of other members. I strongly support the study club concept, and I feel that it should be encouraged in all clinical disciplines in all parts of the country.

Characterization and validation of diagnostic methods

Diagnosis is defined as the determination of disease, but not as the determination of the signs and symptoms thereof. The use of modern diagnostic methodology in the clinic is hampered by cost considerations and by the still widespread belief that, e.g. caries lesions and periodontal breakdown are irreversible processes that need to be detected and treated invasively as early as possible, their measurement thus being irrelevant. Modern instrumental and quantitative methods allow early detection and introduction of noninvasive preventive measures to control the development of the disease. Such methods are also very beneficial in clinical research as they may describe the speed of progress or regress of disease. In epidemiology, such methods reduce the classical problem of calibration of observers. Repeatability, reproducibility, accuracy and validity are defined as method-characterizing quantities, for which examples are given. To express the validity of quantitative methods compared with a quantitative gold standard, the use of scatter plots and correlation and regression methods is suggested. Validation of a dichotomous method with a dichotomous gold standard in terms of sensitivity and specificity is discussed. To validate a quantitative method with a dichotomous gold standard, the receiver operating characteristic curve is suggested, with the requirement that the cutoff value should be determined in relation to the use of the method. However, preferably a quantitative method should not be reduced to a dichotomous one by using a cutoff value, but instead all available information should be used by the diagnostician. It is argued that the use of a secondary standard instead of the accepted gold standard usually leads to inadequate results, even when the validity of the secondary standard is known. Finally, it is argued that the choice of a gold standard is a matter of reasoning and weighing of arguments and not of following a prescribed procedure.

The provision of dental implants in the National Health Service Hospital dental services--a national questionnaire

OBJECTIVE

To assess the activity of consultants in restorative dentistry in the United Kingdom in the provision of osseointegrated dental implants within the National Health Service Hospital service and to evaluate their attitudes concerning the relevant medical and oral factors considered in patient selection for implant treatment.

DESIGN/SETTING

Anonymous postal questionnaire in the United Kingdom.

SUBJECTS

Consultants in restorative dentistry.

RESULTS

Out of the sample of 145, 109 consultants (75%) completed the questionnaire in 1999. 54 of the 109 consultants (49.5%) are involved in the provision of osseointegrated implant treatment, treating an average of 29 cases/year (range 2-150). However, over one third of the respondents treated 10 or less cases/year. 89% worked with oral surgeons as an implant team. 68% used Branemark (Nobel Biocare) implants as their main system. The majority of consultants felt that smoking, psychoses and previous irradiation were the most important medical factors that contra-indicated implant retained restorations whilst untreated periodontitis, poor oral hygiene and uncontrolled caries were the most important oral contra-indications. Many centres were experiencing significant problems with the funding of implant treatment with one centre receiving no funding. The implications for patient care and specialist training are discussed.

CONCLUSIONS

There is a marked variation in the number of patients treated with endosseous dental implants within the United Kingdom National Health Service hospitals. Many consultants treat 10 or fewer patients each year. In the main, there is agreement about the factors that contra-indicate implant treatment; these are in line with national guidelines.

DDAVP (desmopressin; 1-deamino-cys-8-D-arginine-vasopressin) treatment in children with haemophilia B

We tested the response to desmopressin (1-deamino-cys-8-D-arginine-vasopressin; DDAVP) in four patients with haemophilia B [factor IX (F IX) at diagnosis 1.4-5%]. The activated partial thromboplastin time (aPTT) was significantly shortened in all patients. Although there was an up to 1.4-fold increase in F IX levels in three patients, maximal F IX activity remained below 10%. Much more prominent were the increases in F VIII (three- to fourfold), in von Willebrand factor antigen (VWF:Ag; 2.5-fold) and particularly in VWF collagen-binding activity (VWF:CBA; fivefold). These changes were reflected by the prophylactic efficacy of DDAVP for dental surgery. After pretesting, DDAVP could be a useful drug for reducing the need for plasma products for prevention of minor surgical bleeding in patients with mild to moderate haemophilia B.

Clinical presentations of stress distribution in teeth and the significance in operative dentistry

Stress distribution in human tooth structure can be visualized through the use of Moiré fringes, which has improved the clinical understanding of recently identified anatomical structures in molar occlusal surfaces. This article discusses the concept of a "peripheral rim of enamel" and describes the manifestation of compressive and tensile fractures within the peripheral rim of enamel and dentin. It also emphasizes the benefits of microdentistry techniques and minimally invasive preparation designs in the long-term preservation of the natural tooth structure.