Size of the mandibular jaw angle related to age, tooth retention and gender.

The size of the gonial angle was measured in cephalograms of 431 adults attending the Department of Prosthodontics, School of Dentistry, University of Bergen, Norway. The purpose of the work was to conduct a study of the variables often related to the development of the size of the gonial angle, i.e. age, degree of tooth retention, and gender. Descriptive data showed that the edentulous participants had the largest mean angle, the participants in possession of all teeth had the smallest angle, and the partially dentate participants had a jaw angle size between that of the aforementioned groups. Preliminary results of the analysis (ANOVA) showed that the number of teeth had a decisive influence on the size of the gonial angle. The correlation coefficients between size of the gonial angle and age showed that age explained approximately 8-16% of the variation of the angle through its relation with age. Sex differences in age and size of the gonial angle were not statistically significant in any of the three tooth retention categories. Future multiple regression analysis may explain a greater part of the variation of the angle if the analysis is carried out in separate age groups of the three categories.

Re-examination of incisal tooth wear in children and adolescents.

The material presented in this report was derived from a longitudinal study of the development and progress of incisal tooth wear in children and adolescents. The study group was established in 1991-1992 (baseline examination) and consisted of participants between 8 and 15 years of age. They were re-examined in 1993 (interim examination) and in 1994 (final examination). In all, 77 school children (30 females and 47 males) participated in the three examinations. The timespan between baseline and interim was on average 15 months and the period between interim and final examination averaged 16 months. The total observation period was approximately 32 months. Assessments of incisal wear was made on stone casts using the incisal wear index which was shown to have good reproducibility. The results demonstrated that the prevalence and severity of incisal wear had increased significantly with age. In general the rate of incisal wear progression was higher between baseline and interim than between interim and final examination. In this respect certain differences between the tooth types seemed to exist. At baseline the relationship between age and incisal wear was positive and statistically significant for all tooth types. At the final examination the strength of this relationship had decreased for maxillary and mandibular central and lateral incisors. For canine teeth of both jaws the relationship between age and incisal wear was no longer statistically significant at the final examination.

Relationship between incisal tooth wear and the increasing number of permanent teeth in children and adolescents.

The material presented in this report was derived from a longitudinal study of the development and progress of incisal tooth wear in children and adolescents. The study group was established in 1991/1992 and consisted of 77 participants between 8 and 15 years old. All participants were re-examined in 1994. The interval between the first and second examination was approximately 32 months. Each participant was scored for tooth wear of the anterior teeth of both jaws according to the Incisal wear Index (IwI) and the number of permanent teeth and the tooth types present were recorded at each examination. The results showed that the pattern of incisal wear had been maintained during the observation period. Severity of incisal wear increased as the number of teeth increased. The strength of the relationship between incisal wear and the number of teeth decreased during the observation period. At the same time, the number of teeth and the size of the wear increments were negatively correlated indicating that the rate of wear progression decreased as the number of teeth increased.

Relationship between alignment conditions of teeth in anterior segments and incisal wear.

This report describes the alignment condition and incisal wear of the anterior teeth in individuals 16-19 years of age. Tooth alignment and incisal wear were assessed on casts in accordance with two index systems NONAT (non-aligned tooth) and IwI (incisal wear index). Tests of the methods showed that the reproducibility of the assessments of tooth alignment and incisal wear were satisfactory. The results of the study of tooth irregularity demonstrated that the prevalence of non-alignment of one or more of the anterior teeth were much the same (approximately 50%) for the maxillary and mandibular jaws. The highest frequency was found for the maxillary lateral incisors and the mandibular central incisors (approximately 45%). A relationship between the alignment conditions and incisal wear of the anterior teeth was established. It appeared that non-alignment of one or more teeth in one or both jaws was associated with less severe incisal wear of the anterior teeth. This was most pronounced for non-aligned maxillary central incisors and non-aligned mandibular central incisors.

Rehabilitation of mandibular edentulism by single crystal sapphire implants and overdentures: 3-12 year results in 86 patients. A dual center international study.

86 patients, in 2 Scandinavian centers, participated in a prospective study of mandibular edentulism, treated with overdentures supported by Bioceram sapphire implants. Implant success and prosthesis stability as well as parameters for peri-implant health were evaluated. Masticatory function and complications were also documented. The study began in 1991 and clinical treatment of the last patients was completed in 1991. The patients have been followed for at least 3 years, and up to 12 years. 4 patients were lost to follow-up. Of the initial 324 implants, 7 implants failed before prosthetic treatment. 3 patients lost 1 implant each within the 1st year, and 4 patients lost all 4 implants. 16 implants were lost between 36 and 42 months in function, due to lack of osseointegration and pain. The loss of implants could be attributable to an association, not statistically verified, between bone quality and anatomy, with heavy smoking as a risk factor. Based on the remaining implants, the cumulative implant success rates were 95.2%, 91.3%, 91.3%, 91.3% at 3, 5, 10 and 12 year follow-up respectively. The cumulative success rates for overdentures were 96.4%, 92.8% and 92.8% respectively, for the same follow-up periods. Indices for the health of the peri-implant mucosa disclosed no serious inflammatory reactions in the surrounding soft tissues. Patient satisfaction with this form of oral rehabilitation was high in all but 2 patients who experienced discomfort.

A 2-year follow-up study of incisal tooth wear in dental students.

This report was derived from cross-sectional and longitudinal analyses of prevalence, pattern, and severity of incisal wear in 64 dental students who had virtually complete dentitions at the first examination and unchanged dentitions at the re-examination. They were first examined in 1991 and re-examined after 24 months in 1993. The average age of the students in 1991 was 23 +/- 1.7 years. Assessment of incisal wear was made on stone casts based on silicone impression material in accordance with the Incisal wear Index (IwI). The results showed that the prevalence of incisal wear had not changed during the observation period. The severity of incisal wear for maxillary and mandibular central and lateral incisors had remained essentially the same, whereas the severity of wear of maxillary and mandibular canines had increased during the observation period. There was no statistically significant relationship between age and IwI. The wear pattern found for anterior teeth is discussed in relation to the cuspid protection and the group function theories of occlusion.

Longitudinal study of incisal tooth wear in children and adolescents.

This report was derived from a longitudinal study of the development and progress of incisal tooth wear in children and adolescents. The study group was established in 1991/1992 and consisted of 79 participants between 8 and 15 yr. They were reexamined in 1993 and the time span between the first and second examination was 12-14 months. Assessment of incisal wear was made on stone casts based on silicone impression material according to the Incisal wear Index (IwI). The index used was shown to have good reproducibility. The results showed that the pattern of incisal wear had been maintained during the observation period. Prevalence and severity of incisal wear had increased significantly with age. The strength of the suggested linear relationship between age and incisal wear decreased during the observation period. At the same time the growth increments of wear, delta IwI, were negatively correlated with age, indicating that the progression of incisal wear slowed down with increasing age. Description of the true relationship between age and incisal wear outside the age range represented in the sample must await the results of forthcoming studies.

Prevalence, pattern, and severity of incisal wear in dental students.

This paper describes the prevalence, pattern, and severity of incisal wear of anterior teeth in 64 dental students at an average age of 23 +/- 1.7 years with a high number of permanent teeth present. The index used to assess wear on stone casts (IwI) was shown to have good reproducibility. The results indicated that about 98% of the anterior teeth had been worn to various degrees. In both jaws central incisors were most commonly affected by incisal wear, canines followed next in order, and lateral incisors were least commonly affected. Wear of identical teeth on the right and left side tended to be bilaterally symmetrical in both jaws. The results of these initial observations suggest that data from re-examination of this study group will lend themselves to detecting possible changes of the pattern and severity of incisal wear of permanent anterior teeth.

Longitudinal relationship between incisal tooth wear and periodontal condition.

The purpose of the study was to examine the relationship between the longitudinal development of incisal tooth wear and periodontal conditions in 51 persons. Stone casts obtained at the ages of 15 and 27 yr were used to assess incisal wear according to a graded scale, the Incisal wear Index (IwI). The wear increase after 12 yr, delta IwI, was related to the various health index scores at the age of 15 yr, including the Plaque Index (PlI) and Gingival Index (GI) systems. The chi-square tests showed a statistically significant association between delta IwI and periodontal condition in 15-yr-olds. Thus, relatively low PlI and GI values were accompanied by relatively high delta IwI values. It was concluded that in 15-yr-olds, PlI and GI levels are clinical predictors of future wear (delta IwI) of maxillary and mandibular central incisors. Pocket depth (PD) was a less valuable clinical predictor of such wear.

Longitudinal relationship between incisal occlusion and incisal tooth wear.

The purpose of the study was to evaluate the longitudinal relationship between incisal wear of central incisors and the size of vertical overbite (OB) and horizontal overjet (OJ). Stone casts of 51 subjects were used for the determinations. Casts were obtained when the subjects were 15 and 27 years old. Statistical analysis was performed with the t test for paired samples, the chi-square test of association. Pearson's product moment correlation coefficient, and Spearman's rank correlation coefficient. Both overbite and overjet diminished after 12 years, and incisal wear increased. It was concluded that increase in age, incisal wear, vertical overbite and incisal occlusion (OB/OJ) are clinical predictors of wear of maxillary and mandibular central incisors in adolescents.

Adaptation of resin facings to cast gold alloy restorations in the mouth.

The occurrence of marginal spaces between the resin facing and gold alloy framework in 176 crowns and bridge retainers was studied. The restorations were made for canine teeth. The assessment of spaces at the cervical alloy-resin junction was carried out by examining slides of the buccal surfaces taken after application of disclosing agent. Spaces at the incisal alloy-resin junction were assessed by examining resin models under the stereomicroscope. Randomly selected restorations were grouped and examined with reference to length of clinical service (1, 3, 6, and 9 years). The methods were tested for reliability and consistency. The results showed that the frequency of cervical spaces tended to increase with length of clinical service, whereas the frequency of the incisal spaces seemed to remain unchanged. The most severely worn facings had the highest frequency of cervical spaces. In contrast, the least worn facings seemed to have the highest frequency of incisal spaces. For both the cervical and the incisal spaces the highest frequencies were found for relatively long resin facings.

The pattern and severity of wear of resin facings in fixed prosthetic restorations in vivo.

Wear of prosthodontic resin facings in 176 metal-resin canine crowns and retainers for fixed partial dentures was studied in clinical photographs and assessed using a graded scale. Four cross-sectional groups of restorations were studied according to length of clinical service (1, 3, 6, and 9 years). The criteria used during the examination described loss of substance in relationship to the metal cast framework. The method was tested for reliability and consistency. The results showed that the extent of wear increased with increasing time of clinical service (P less than .05). More severe wear scores were assigned to restorations in female patients than to those in male patients (P less than .05), to the mandibular facings compared to those in the maxillae (P less than .05), and the incisal areas of the facings compared to the cervical areas (P less than .05). Patients instructed in oral hygiene measures tended to show more severe wear than noninstructed individuals. A significant association was established between the ratio of vertical and horizontal overlap and the wear scores. Increasing VO/HO ratios seemed to be accompanied by increasing wear.

Fixed restorations produced for recipients of dental prosthodontic treatment. A comparison between general dental practice and a dental school.

Fixed prosthodontic work ordered by general dental practitioners was examined through registrations made in commercial dental laboratories. A comparison was made with similar data from student files on fixed prosthodontic treatment at the University Clinic in Bergen, Norway, which is located in the same geographic area. The results indicated that the distributional pattern of fixed restorations within the dentition was much the same in the individuals attending the general dental practitioners as in those treated at the dental school. While the practicing dentists preferred metal-ceramics in most cases, most of the restorations inserted at the dental school were based on the metal-resin technique.

Changes over time in the clientele and restoration pattern in a dental school prosthodontic department.

The clientele and the production of single artificial crowns and fixed partial dentures in the Department of Prosthodontics were compared from 1964/68-1982/87. In the first period 65 per cent of the single crowns were made for women versus 55 per cent in the second. In the first period 69 per cent of the crowns were placed in the upper jaw as against 60 per cent in the second period. On average 1.6 crowns were made per female patient in the first period versus 1.4 per male patient. In the second period both sexes averaged 1.8 units. In both jaws the percentage of root-filled crowned teeth had increased in the second period to 60 per cent from 48 per cent in the upper jaw and 46 per cent in the lower jaw. In both sexes maxillary and mandibular teeth were crowned on average 13 years later in the second period than in the first. Sixty per cent of the fixed partial dentures were made for women in the first period versus 55 per cent in the second. In the first period 74 per cent of the bridges were made for the upper jaw as against 70 per cent in the second period. The mean pontic to abutment ratio was 0.7 in both periods. The maximum number of bridges in the first period were made for patients 40-59 years of age versus 50-69 years in the second period.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial mouth recording of plaque, gingivitis and probing depth in adolescents.

Selection of teeth representative of the whole dentition has been used in clinical and epidemiological investigations. The present study was carried out to assess the relationship between 3 different subsets of teeth and the whole dentition for the plaque index, gingival index and probing depth. The selections were: the subset described by Ramfjord (16, 21, 24, 36, 41, 44), the CPITN Alternative I subset (17, 16, 11, 26, 27, 37, 36, 31, 46, 47) and the CPITN Alternative II subset (16, 11, 26, 36, 31, 46). The comparisons were performed on data obtained for 15-year-old adolescents. A strong correlation was observed between the whole dentition and each of the subsets for all assessments. The distribution of scores of the Ramfjord selection and the whole dentition was not statistically different. Corresponding comparisons showed that the distribution of scores of the CPITN selections and the whole dentition was statistically different. Plaque and gingival index scores of these selections underestimated 0 scores and overestimated 2 + 3 scores. Probing depths less than or equal to 2 mm were underestimated and probing depths greater than or equal to 4 mm overestimated. The bias associated with the CPITN Alt I was more pronounced than that of the CPITN Alt II subset of teeth in the adolescents examined.

Clinical and radiographic observations after 6 years on bridge abutment teeth carrying pinledge retainers.

A group consisting of 108 bridge recipients (71 female, 37 male) with a total of 114 bridges retained solely (n = 40) by pinledges or retained by a combination (n = 74) of pinledges and complete crowns was examined clinically and radiographically 6 years after completion. The study was to review evidence of any displacement of bridges as well as the incidence of periapical changes and carious lesions of those abutment teeth fitted with pinledges (n = 210). The results showed that bridges retained solely by pinledges had become displaced more frequently than bridges retained by a combination of crowns. The failure rates (%/year) for bridges retained solely by pinledges was 2.5% and for bridges with a combination of retainers 0.25%. Three teeth (1.4%) experienced pulp exposure during the preparatory work and 6 teeth (2.8%) had been or had to be rootfilled after 6 years. Carious lesions had developed in 6 abutments (1.9%).

Alveolar bone loss in bridge recipients after six and twelve years.

For a long time the major emphasis in prosthetic dentistry was placed on the technical and mechanical aspects of the different procedures and material used. The relationship between the prosthetic treatment and the periodontal tissues received less attention. As a consequence early results of epidemiological studies were not encouraging since they revealed that prosthetic treatment may be an important contributory factor in the aetiology of periodontal diseases. Research during the last two decades into the aetiology and pathogenesis of these diseases has revealed major principles and finer details relating to the mechanisms of their initiation and progression. Recent research has shown that cooperation between the prosthodontist and the periodontist, based upon agreed fundamental concepts, may give encouraging results in the prosthetic replacement of lost teeth. The study reported here assesses the effects upon the periodontal tissues of fixed bridges over a six and twelve year period.

Margin fit of metal crowns and bridge retainers.

The margin fit of metal crowns and bridge retainers was examined radiographically in individuals who were registered to receive treatment at the School of Dentistry, University of Bergen. One sample consisted of 184 individuals registered in 1967-68 and another one of 232 individuals registered in 1982-83. In all, 2057 proximal surfaces could be examined. The margin fit was scored as excess, deficit, or satisfactory. In the 1967-68 single-crown sample margin excess was recorded for 66%, margin deficit for 8%, and satisfactory fit for 26%, on the average. In the 1982-83 single-crown sample margin excess was recorded for 36%, margin deficit for 5%, and satisfactory fit for 59%. In the 1967-68 sample bridge retainer margins on the average scored 60% excess, 10% deficit, and 30% satisfactory fit. In the 1982-83 bridge retainer sample margin excess amounted to 33%, margin deficit to 4%, and satisfactory fit to 63%. The possible reasons for the differences between the two samples are discussed.

Marginal adaptation of resin veneers to gold castings.

The magnitude of the fissures between resin facing materials and gold castings was measured by light microscopy. Two different products and two different processing procedures were used. The effect of water sorption on the fissure size was also studied. Mean fissure sizes varied between 3 and 25 microns. The best adaptation between the resin material and the gold alloy was obtained by the conventional closed flasking technique compared with free processing in a pressure vessel. When processed by closed flasking the product that did not contain microfiller showed fissure widths approximately one fourth of those resulting from the open processing technique. The other product, containing microfiller, was less sensitive with regard to processing. The effect of water sorption on the fissure width was most evident in the test groups containing specimens processed in flask.