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Biomedical subjects

Ivar A Mjör

Publications and source records attributed to Ivar A Mjör.

At least 19 recordsLinked to original sources
PubMed2006

The safety of nickel containing dental alloys.

Nickel is a constituent of many dental alloys. This paper reviews mainly papers published after 1985 with regards to biological reactions to nickel in dentistry. Nickel is an allergen, but there is no evidence that individual patients are at a significant risk of developing sensitivity solely due to contact with nickel-containing dental appliances and restorations. Hypersensitivity reactions to nickel are only likely to occur with prior sensitization from non-dental contacts and even these are rare. Clinical evidence has been presented to show that small doses of nickel, e.g. from dental appliances, may induce tolerance to this allergen. The papers reviewed report low rates of release of nickel from dental alloys. Some nickel compounds, which are mildly cytotoxic, have been implicated as carcinogens by inhalation in industrial settings, but these compounds are not present in dentistry-related operations, including dental technology procedures. Nickel-containing alloys and compounds have not been associated with increased cancer risk by oral or dermal routes of exposure. It is concluded that, subject to use according to established techniques, nickel-containing dental alloys do not pose a risk to patients or members of the dental team.

Carcinogens↗
PubMed2006

Two-year clinical evaluation of repair versus replacement of composite restorations.

PURPOSE: To investigate the effectiveness of alternative treatments to the replacement of resin-based composite (RBC) restorations through a prospective longitudinal cohort clinical study. MATERIALS AND METHODS: Forty patients aged 27 to 77 years (mean=55) with 88 RBC restorations, with one or more features that deviated from ideal, participated in the study. They were assigned to five treatment groups: repair (N=25), sealing of defective margins (N=13), resurfacing (N=18), replacement (N=16), and the no-treatment group (N=16). The replacement and no-treatment groups served as comparison groups and received random assignment. Two clinicians examined the quality of the restorations (N=88) prior to the assigned treatment, and at subsequent recalls (1 and 2 years) using a modified Ryge criteria (Alfa, Bravo, and Charlie, meaning clinically excellent, clinically acceptable with one or more features that deviated from ideal, and clinically unacceptable, respectively) that observed (1) color, (2) marginal adaptation, (3) anatomic form, (4) surface roughness, (5) marginal staining, (6) bulk discoloration, (7) contact, (8) secondary caries, (9) postoperative sensitivity, and (10) luster. RESULTS: At 1- and 2-year recalls, 66 (75%) and 58 (66%) restorations were examined. Kruskal-Wallis Test showed significant differences for marginal adaptation and marginal staining for both 1- and 2-year recall exams (p < .05). The repair, sealant, and replacement groups presented significant improvement when compared with the no-treatment group for marginal adaptation. The repair and replacement groups showed superior results when compared with the no-treatment group for marginal staining. CONCLUSION: RBC restorations that present less-than-ideal marginal adaptation and stained margins are better off being repaired. CLINICAL SIGNIFICANCE: Repair of resin-based composite (RBC) restorations is a conservative option for treatment of RBC restorations with inadequate marginal adaptation and marginal staining.

Adult↗
PubMed2006

Two-centre evaluation of a resin composite/ self-etching restorative system: three-year findings.

PURPOSE: This two-centre study evaluated the clinical performance of Class I and Class II restorations of the giomer material Beautifil, placed using Fluorobond, a self-etching adhesive system, to determine the suitability of the test system as an alternative for the restoration of posterior teeth. MATERIALS AND METHODS: A total of 108 restorations, comprising 72 Class II and 36 Class I restorations, was placed predominantly in molars (82%). Evaulations using modified USPHS/Ryge criteria were conducted at baseline and thereafter at 6 months and 1, 2, and 3 years. Die stone replicas of the restored teeth were examined retrospectively. RESULTS: A total of 5 restorations was found to fail during the study-- 3 in the first year and 2 during the third year of the study. Occlusal marginal adaptation was less than ideal at baseline in 11% of cases, primarily as a consequence of overcontouring, as observed in the die stone replicas. The combined percentage Alpha ratings at 3 years were: colour match, 98%; marginal adaptation (occlusal), 78%; marginal adaptation (proximal), 97%; anatomic form (occlusal), 99%; anatomic form (proximal), 95%; surface roughness (occlusal), 100%; surface roughness (proximal), 100%; marginal staining (occlusal), 90%; marginal staining (proximal) 81%; interfacial staining (occlusal), 99%; interfacial staining (proximal), 100%; contacts (occlusal), 95%; contacts (proximal), 93%; sensitivity, 100%; secondary caries, 100%; lustre of restoration, 100%. CONCLUSION: It is concluded that the 3-year performance of Fluorobond-bonded Beautifil for Class I and II restorations demonstrated some marginal changes, but most of the direct evaluation ratings were > 90% Alpha, with the performance observed being similar in the two centres.

Adult↗
PubMed2005

Research in general dental practice.

Spurred by an initiative by the National Institute of Dental and Craniofacial Research in the USA, this article presents the need for a change in clinical dental research towards practice-based research. It outlines the shortcomings of past and present-day research in dentistry, with emphasis on the lack of clinical relevance of much of the research performed. The slow transfer of sound research findings to clinical practice is also a major problem. The article reviews some problems related to restorative dentistry and how they have adversely affected general dental practice. Practice-based research places emphasis on the problems experienced by clinicians in the routine care of patients. Clinicians should be linked together in research networks. The problems they face in dental practice and the clinical experience they have will form the basis for studies by the network. Experienced clinical researchers will provide guidance and statistical support for the studies initiated by the clinicians.

Dental Care↗
PubMed2005

Clinical diagnosis of recurrent caries.

BACKGROUND: The clinical diagnosis of recurrent caries is the most common reason for replacement of all types of restorations in general dental practice. Marked variations in the diagnosis of the lesions have been reported. The prevention of recurrent lesions by the use of fluoride-releasing restorative materials has not been successful. TYPES OF STUDIES REVIEWED: The author focused on practice-based studies in the literature. These studies are not scientifically rigorous, but they reflect "real-life" dental practice. Few experimental studies on recurrent carious lesions in vivo have been reported, but bacteriological studies indicate that the etiology is similar to that of primary caries. RESULTS: Recurrent carious lesions are most often located on the gingival margins of Class II through V restorations. Recurrent caries is rarely diagnosed on Class I restorations. The diagnosis is difficult, and it is important to differentiate recurrent carious lesions from stained margins on resin-based composite restorations. Over-hangs, even minute in size, are predisposed to plaque accumulation and the development of recurrent caries. The development of recurrent lesions is unrelated to microleakage. CLINICAL IMPLICATIONS: As recurrent carious lesions are localized and limited, alternative treatments to restoration replacement are suggested. Polishing may be sufficient. If not, exploratory preparations into the restorative material adjacent to the localized defect can reveal the extent of the lesion. Such explorations invariably show that the lesion does not progress along the tooth-restoration interface. The defect, therefore, may be repaired in lieu of being completely replaced. Repair and refurbishing of restorations save tooth structure. These simple procedures also increase the life span of the restoration.

Dental Caries↗
PubMed2004

Cariology in Japanese dental schools.

AIM: The aim of this study was to evaluate the teaching of cariology in Japanese dental schools. DESIGN: Postal questionnaires were sent to all Japanese dental schools. PARTICIPANTS: Twenty-five of the 29 Japanese dental schools (response rate: 86%). RESULTS: The results were in many areas similar to those reported from North America. The non-surgical approach to the management of primary caries predominated, but no schools used bacteriological tests in caries diagnosis and only one school recommended antibacterial treatment. Four of the 25 responding schools advocated the treatment of primary enamel lesions by surgical intervention while three awaited operative intervention until the lesions had reached the middle third of the dentine. Recommendation of fluoride treatment was less common than in North America. The use of electronic devices to diagnose occlusal caries lesions was more common than in North America, but 'explorer catch' was the most frequently used method to diagnose primary and secondary caries in dental schools in both regions. CONCLUSION: Research in cariology over the years has led to altered views on how and when to treat caries lesions. The interpretation of research findings and the transfer of knowledge by teachers in dental schools have an impact on the practice of operative dentistry, but the diversity in the teaching of cariology indicates that the interpretation and implementation of modern principles in the treatment of caries differ quite markedly in Japanese dental schools.

Curriculum↗
PubMed2004

The effect of mechanical undercuts on the strength of composite repair.

BACKGROUND: The authors conducted an in vitro study to test the hypothesis that undercuts prepared in old composite restorations could improve the strength between the restoration and a flowable composite as repair material. METHODS: The authors used three composites to fabricate cylinders as repair substrates. The etched-only group was ground, etched, dried and built up with a flowable composite. For the undercut group, the authors introduced arrays of fissures on the surfaces before preparing the specimens for subsequent buildup in the manner described for the etched-only group. They made nonrepaired cylinders for baseline measures of strength. They sliced all finished cylinders into slender bars with a diamond saw. Flexure strength values were determined by a three-point-bending test. RESULTS: Nonrepaired bars exhibited statistically significantly higher flexure strength values than did repaired bars, as determined by Wilcoxon rank sum test. Two-way general linear model showed that both material (P < .0001) and undercut (P = .0207) exhibited a statistically significant influence on the repaired flexure strength. Repair substrate with elastic modulus close to that of repair material exhibited a greater percentage of recovery of the respective cohesive strength. Compared with the etched-only group, the undercut group yielded a higher mean flexure strength with one composite but a lower mean flexure strength with the other two. Examination of the fractured surfaces showed that a significant number of undercuts were filled only partially. CONCLUSION: Flexure strengths of repaired specimens always were lower than the cohesive flexure strengths of the materials being repaired. Undercuts did not generally improve repair strength. CLINICAL IMPLICATIONS: Small undercuts on the surface of composite often are difficult to fill completely, resulting in areas of stress concentration that result in no improvement in the repair strength.

Analysis of Variance↗
PubMed2004

Esthetic dentistry in North American dental schools.

OBJECTIVES: Esthetic dentistry is among the most dynamic areas of contemporary clinical dentistry. Teaching programs in dental schools have a strong effect on the practice of dentistry, not only for recent graduates, but also for established clinicians, especially with respect to new techniques and concepts. The purpose of the study reported here was to assess the frequency and extent of the teaching of esthetic dentistry in North American dental schools and to report how it differs among the various schools. MATERIALS AND METHODS: A 19-question survey was mailed to 64 North American dental schools. The questions inquired about the priority given to the teaching of esthetic dentistry in the school; how the subject was taught (through regular curricular courses; through a multidisciplinary approach or through elective classes); the duration of the esthetic dentistry course; the nature of the course content (theoretical or practical); the esthetic procedures taught to undergraduate students; the level of interaction among different disciplines in the teaching of esthetic dentistry; and the techniques and commercial materials used. The responses were summarized as percentages based on the number of schools that responded to each question. RESULTS: Fifty-two (81%) of the 64 dental schools completed and returned the questionnaire. Twenty-five of these schools (48%; designated group A) reported having a course exclusively for the teaching of esthetic dentistry. Twenty-seven schools (52%; designated group B) reported that esthetic dentistry was addressed in multiple courses, i.e., no specific course was available. Four schools in group B (15%) were in the process of developing a separate course for esthetic dentistry. In group A schools, esthetic dentistry was taught mainly in the operative dentistry department or division. The most frequent course duration was 4 to 6 months, but there were marked variations. Thirteen (52%) of these 25 schools had didactic and practical teaching at both the preclinical and the clinical levels. The schools in group B reported that only clinical instruction in esthetic dentistry was provided. Several concerns were addressed in the courses offered in group A schools: extrinsic and intrinsic discoloration, bleaching, diastemas, malformation and malpositioning (the latter including rotation, intrusion and labio-linguoversion), and replacement of amalgam and gold restorations. Only 7 (28%) of the group A schools reported having the support of an inhouse laboratory. The esthetic procedures taught were similar for schools in group A and group B. The use of direct posterior composite restorations, all-ceramic crowns and nonvital bleaching was more common among group B schools. Ceramic inlays, onlays and indirect posterior composite restorations were not taught by 4 (16%) of the schools in group A and 7 (26%) of the schools in group B. CONCLUSIONS: The teaching of esthetic dentistry in North American dental schools is highly variable and in many schools is shared among different disciplines. Dental schools should work together to establish the parameters for teaching this subject and should formulate the necessary standards for education and research in this new field.

Canada↗
PubMed2003

Reasons for the placement and replacement of crowns in general dental practice.

AIMS: The purpose of the study was to apply established methods to survey reasons for the placement and replacement of crowns in general dental practice in the United Kingdom. MATERIALS AND METHODS: One hundred and twenty-eight general dental practitioners were recruited. Participants recorded the principal reason for the provision of each initial and replacement crown they provided over a 12-week period. RESULTS: Overall, data were collected from 92 practitioners in respect of 1714 patients and 2164 crowns, of which 1452 (67%) were initial placements and 712 (33%) replacements. The teeth most frequently crowned were maxillary incisors (33%), with 72% of the crowns surveyed being of the porcelain bonded to metal variety. Overall 64% of the initial placement crowns were provided because of restoration failure (26%) or tooth fracture (38%). The most common reason for crown replacement was crown failure (27%). CONCLUSION: It is concluded that surveys of the type reported may provide new insights into the reasons for and pattern of provision of initial placement and replacement crowns in clinical practice. In this study the most common reason for the provision of initial placement crowns was tooth fracture. The most common reason for the replacement of crowns, notably porcelain jacket crowns, was crown fracture.

Chi-Square Distribution↗
PubMed2003

Teaching students the repair of resin-based composite restorations: a survey of North American dental schools.

BACKGROUND: The purpose of this study was to evaluate whether North American dental schools teach students to repair resin-based composite, or RBC, restorations and to compare the findings with those from similar European surveys. MATERIALS AND METHODS: The authors mailed a 15-item questionnaire to 64 dental schools in the United States, Canada and Puerto Rico. The survey asked whether the school taught repair of RBC restorations and inquired about the respondent's experience with such procedures. Questions also elicited reasons why schools taught or did not teach repair, information in regard to relevant decision-making processes, criteria for deciding whether to perform repairs and the nature of the instruction (theoretical, practical, preclinical or clinical). RESULTS: Fifty-two (81 percent) of 64 schools participated in the survey. Thirty-seven (71 percent) of the respondents reported that they taught undergraduate students repair techniques as an alternative to replacing failing RBC restorations. Twenty-seven (73 percent) of these 37 schools reported that such teaching was at the clinical level, while only three schools (8 percent) reported that it was included in formal lectures as part of preclinical courses. The major reasons given for teaching students how to repair RBC restorations were tooth structure preservation and reduction of potentially harmful effects on the pulp. Indications included the correction of marginal defect and marginal discoloration. CONCLUSIONS: More than one-half of the respondents reported that they taught repair of RBC restorations and that patients were willing to accept such treatment. Most schools considered the repair of RBC restorations to be a definitive measure and reported that, on average, expected a repaired RBC restoration to have a longevity of four years.

Canada↗
PubMed2003

Defective direct composite restorations--replace or repair? A survey of teaching in Scandinavian dental schools.

A questionnaire based survey was undertaken in Scandinavian dental schools to investigate aspects of the teaching of the repair of failing direct composite restorations, as a conservative alternative to total restoration replacement. The findings indicate that all undergraduate students in Scandinavian schools are taught and gain clinical experience in the repair of direct composite restorations. Although the findings reveal general agreement in relation to the teaching of reasons and operative procedures for the repair of direct composite restorations, variations were found in relation to the teaching of indications for, and the expected longevities of such repairs.

Attitude of Health Personnel↗
PubMed2002

Placement and replacement of restorations in primary teeth.

This practice-based study aimed to record the use of restorative materials, the type of restoration by class, and the reason for and the age of failed restorations in primary teeth by means of a survey of placement and replacement of restorations in 1996 and 2000/2001. Written alternative criteria for placement and replacement of restorations were provided for the participating clinicians. Details on 2281 restorations showed that primary caries was the main reason for inserting restorations in primary teeth. Replacements of failed restorations represented 14% of the fillings (n = 2040) in 1996 and 9% in 2000/2001 (n = 241). More than 80% or the fillings in primary teeth were of tooth-colored material, predominantly of the light-cured type. About 50% of failed amalgam and glass ionomer-type restorations were replaced due to secondary caries. The median age of amalgam restorations (3 years) was significantly higher than that of tooth-colored restorations (2 years). Any possible advantage of a cariostatic effect of glass ionomer-type materials is apparently annulled by their short longevity compared with amalgam.

Child↗
PubMed2002

Self-etching primer and resin-based restorative material: two-year clinical evaluation.

PURPOSE: This study was undertaken to evaluate the performance of posterior restorations placed using a self-etching primer (Fluorobond, Shofu Inc., Kyoto, Japan) and a universal resin-based restorative material (Beautifil, Shofu Inc., Kyoto, Japan). MATERIALS AND METHODS: The 61 restorations evaluated were 26 Class I and 35 Class II that were placed by two clinicians in 31 patients. Two other calibrated clinicians evaluated the restorations using United States Public Health Service (USPHS)/Ryge criteria observing the following characteristics: color match, marginal adaptation, anatomy, roughness, marginal staining, interfacial staining, contact, secondary caries, and luster. Restorations were placed under rubber dam isolation. Chi-squared and Fisher's exact tests were used for statistical analysis (p = .05). RESULTS: All the restorations were assessed at baseline and alfa scores predominated for all criteria. At the 12-month recall examination, one patient dropped out of the study and two restorations were replaced by a clinician not involved in the project. At 24-month recall, 58 restorations were examined (23 Class I and 35 Class II). From baseline to 24 months, 19 of the 44 restorations changed from alfa to bravo and 13 from bravo to alfa for a variety of reasons. No significant differences were found for any of the clinical criteria (p > .05). The 2-year recall substantiated the 1-year results. CONCLUSION: Beautifil and the self-etching primer Fluorobond provided satisfactory restorations after a 2-year observation period. CLINICAL SIGNIFICANCE: Beautifil restorative material and Fluorobond bonding system provided satisfactory results when placed in Class I and Class II preparations for a period of 2 years.

Acid Etching, Dental↗