Qualitative assessment of stress distribution during insertion of endodontic posts in photoelastic material.

OBJECTIVES: The purpose of this study was to investigate the stress patterns associated with prefabricated endodontic posts during the various stages of insertion according to a number of design characteristics. METHODS: In a photoelastic material with elastic properties comparable to dentin, analyses were performed of the overall stress patterns with polarized light revealing substantial differences in stresses generated by the various posts. The effects of variations in design for certain configurations of the posts were also assessed. RESULTS: One geometric feature was the retentive thread of the post. The stress patterns within the photoelastic material revealed a homogeneous distribution of stress along the entire length of the thread, and more threads induced additional stress. The stress recorded with a vent when the pitch of the thread was 0.8-1.0 mm was classified as minimal-to-mild stress. Another geometric feature considered was the head (coronal extension) of the post. Minimal stress was recorded in the material in contact with the head and the apical end of the post when the contact surface of head was more than 3 mm2. CONCLUSIONS: This study suggests that during insertion of threaded posts the least stress occurs when the head contact surface is sufficient (> or = 3 mm2). A thread with a pitch of 0.8-1.0 mm is most desirable in stress reduction. The number of windings should also be limited (less than six windings) as samples with a substantial number of windings (N = 13 or 30) produce severe stress.

Porosity in resin composite core restorations: the effect of manipulative techniques.

Forty acrylic resin duplicates of an endodontically treated and extracted human molar were restored with two resin composite materials for core restorations. Two different manipulation techniques, bulk insertion and syringe application, were used. In a simulated clinical setup, the core buildups produced by the different manipulation techniques were investigated for voids. In 20 duplicates, a post was placed to simulate a metal post and resin composite core buildup. The syringe technique produced significantly fewer incorporated voids for both resin composite core materials than did the bulk insertion technique. It was not possible to demonstrate a relationship between the presence of voids and the presence of a metal post.

Satisfaction with reduced dentitions in elderly people.

Natural dentitions of elderly people are often reduced and the remaining teeth are heavily restored. It is unknown whether they are satisfied or dissatisfied with this situation. To get more insight into this phenomenon 320 dentate non-institutionalized elderly subjects were clinically examined and interviewed by means of a questionnaire. Analysis of the data showed that only 13% of the subjects had at least a complete dentition from the right first molar to the left first molar; 50% had less than four occlusal units, 39% of the subjects were wearing a removable partial denture. Ninety per cent of the subjects was satisfied with the dental state and nearly all subjects mentioned they could chew well (97%), despite the fact that 91% of the subjects mentioned they had to deal with one or more dental discomforts. Satisfaction decreased significantly when the number of the occlusal units was reduced or a removable partial denture was present. The conclusion is drawn that although the dentitions of the elderly are often reduced they are, in general, satisfied with their dental state.

Clinical performance of different post and core systems--results of a pilot study.

During the period 1974-1986, 112 post and core build-ups were inserted in 74 patients. The build-ups consisted of a metal prefabricated post (Dentatus, Unimetric or Radix) in combination with a composite core. After an average follow-up period of 7.9 years, 14 failures (12.5%) were noticed. Eight teeth could be rerestored and six teeth had to be extracted. However, when correction was made for teeth with a bad initial prognosis and for extractions not related to the build-up restoration, eight failures remained caused by failure of the build-up (7.5%). The Dentatus posts seemed to increase the risk for failure.

Survival rate and failure characteristics of the all metal post and core restoration.

In this retrospective study 516 teeth restored with a cast post and core build-up were followed from 1970 till 1990. The data was derived from the dental records of 283 dental clinic patients treated by senior students. The survival rate was found to be 82% after 10 years for post and cores in the anterior region. The most frequent failure characteristic was recementation (46%), followed by rerestoration (32%). The solitary provisions in posterior teeth showed a relative high survival rate, compared with other tooth-types and locations.

Oral function in dentate elderly with reduced dentitions.

This study covers the characteristics of reduced dentitions in a population of elderly people. The sample consisted of 329 independently living individuals between 55 and 75 years of age. They all had one or more natural teeth and were all interviewed and investigated clinically. The findings showed that 13% of the subjects had a natural dentition with at least the first molars; 4-7 natural occlusal units (defined as 'pairs of opposing teeth that support the occlusion') occurred in 37% of the subjects; 1-4 natural occlusal units in 41% and 0 units in 9% (only anterior contacts). A removable partial denture was worn by 39% of the subjects; most of them were acrylic based dentures (61%). The percentages of restored teeth per subject were high. The need for further restorations, however, was low. Periodontal problems were uncommon; 25% of the subjects had one pocket above 5 mm; 8% had severe problems. Poor oral hygiene was present in a quarter of the cases. Most of the subjects (70%) had no pain or noises in the temporomandibular joint. Only 10% of subjects had more than one sign of craniomandibular dysfunction. Most of the subjects (85%) visit their dentist regularly and 65% had their last tooth extraction more than three years ago. A majority mentioned that they have never had problems with their dentition in the past; 50% had had no real toothache for the last five years. However, problems with food-packing were often mentioned. It can be concluded that, although the dentitions of the elderly in this population are often reduced, their dentitions are in general in good condition and few give TMJ problems.

[The clinical behavior of metal-composite post and core build-up. Results of a pilot study]. / Het klinisch gedrag van metaal-composiet stiftopbouwen. Resultaten van een pilot-studie.

During the period 1974-1986 112 post and core buildups were inserted in 74 patients. The buildups consisted of a metal prefabricated post (Dentatus, Unimetric or Radix) in combination with a composite core. After an average follow-up period of 7.9 years 14 failures (12.5%) were noticed. Eight teeth could be rerestored and six teeth had to be extracted. However, when correction was made for teeth with a bad initial prognosis and for extractions not related to the buildup restoration, eight failures remained caused by failure of the buildup (7.5%). Half of these concerned Dentatus posts.

Cingulum bar as a major connector for mandibular removable partial dentures.

In the international literature and textbooks, the cingulum bar as a mandibular major connector is often neglected. It is a viable alternative to a lingual bar where the distance between the marginal gingivae and the mucolingual fold is restricted. It also provides indirect retention and thereby eliminates the need for a conventional indirect retainer. Patient comfort with an RPD with a cingulum bar seems acceptable because the connector forms one unit with the anterior teeth. The replacement of a lost natural anterior tooth with a denture tooth is not difficult. The metal bulk of the bar may be a disadvantage and esthetics may be compromised if spacing is present. Marked lingual inclination of the anterior teeth prevents the use of a cingulum bar. Different laboratory requirements are discussed.

[The cingulum bar as major connector for removable partial dentures]. / De frameprothese met cingulumbar.

In the international literature, the dental connector as major connector is often neglected. This major connector seems to be preferable in many cases, as is discussed in this article.

[Natural dentition of the elderly. An occlusal concept]. / De natuurlijke dentitie van de oudere mens. Een occlusieconcept.

Treatment of the impaired dentition of the elderly has to be focused on maintaining the strategic natural teeth. This means not necessarily the preservation of all teeth. At least a minimal functional level should be preserved.

Twenty years of dental treatment in the Dutch Armed Forces.

A mixed longitudinal descriptive survey has been designed to answer some questions regarding the effectiveness of dental health care. For a period of 20 years the dental records of 845 Dutch servicemen have been analyzed with regard to the amount of dental treatment per tooth and surface. Cross-sectional results of this study are compared with those of other studies. Generally the results of this study concerning restorations and extractions per tooth type accord with the literature. The provision of full dentures is relatively low in the Army.

Prosthodontic treatment and retreatment of 845 servicemen.

Results of the fixed prosthodontic treatment of 845 servicemen have been shown. Similar to other studies, most crowns were placed in the maxilla. Differences and similarities to other studies were found regarding the fixed prosthodontic treatment per tooth type. The fact that 15% of the crowns placed in the period 1958 to 1977 needed retreatment should be a subject for further analysis.