[Extension of (extremely) shortened dental arches by fixed or removable partial dentures]. / Verlenging van (extreem) verkorte tandbogen met vaste of uitneembare prothetische constructies.

Whether a shortened dental arch needs to be extended depends on the degree of the shortening. Four categories of shortened dental arches can be distinguished: 1. slightly shortened dental arches; 2. moderately shortened dental arches; 3. extremely shortened dental arches; and 4. asymmetrical extremely shortened dental arches. Decision-making on extending a shortened dental arch should be based on oral function and the patient's perceived impact on oral health-related quality of life. According to this principle, there is no evidence for extending slightly shortened dental arches. Extending moderately shortened dental arches is indicated in exceptional cases, especially for aesthetic reasons. In the case of (asymmetrical) extremely shortened dental arches there are reasons for extension. The extension can be restricted to restoring the arch to the level of a moderately shortened dental arch. With this treatment strategy, it is possible in many cases to conform to the current trend of using fixed partial dentures rather than removable partial dentures.

A systematic review of single-tooth restorations supported by implants.

OBJECTIVES: To make an inventory of clinical studies on single-tooth restorations supported by implants using a systematic review procedure and to aggregate overall survival results. DATA SOURCES: Papers referring to single-tooth implants were located by a MEDLINE search 1990 to April 1998. Three hundred and twenty references were found, and they were subjected to a systematic review procedure. STUDY SELECTION: A three-step inclusion/exclusion procedure was applied to identify papers that represented: good scientific practice (GSP), reported results of all patients, implants and crowns for more than 2years, and had sufficient data to generate life-table analyses. The outcomes were 'implant failure' and 'crown completion'. Nine studies survived. These data showed an overall mean GSP of 0.37 with a predicted 4year implant survival of 97% (n=459), and an uncomplicated crown maintenance of 83% (n=240). CONCLUSION: Single-tooth implants show an acceptable short-term survival of 4years, but crown complications are common.

[The convergence angle of crown preparations with clinically satisfactory retention]. / De convergentiehoek van kroonpreparaties met klinisch voldoende retentie.

A method was developed to measure the convergence angle on dies of complete crown preparations. The 132 dies measured revealed a surprising range in the convergence angles (15.5 to 30.2 degrees). The mandibular molar preparations had the greatest convergence angle. The design of mandibular molar preparations should be the subject of additional research.

An experimental porcelain repair system evaluated under controlled clinical conditions.

Twenty metal ceramic crowns on upper premolars in 12 patients were purposely fractured before seating with temporary cement. The fractured crowns were repaired in situ with an experimental porcelain repair system. The initial results were satisfactory both esthetically and functionally. However, only 50% of the repairs were intact by the end of the 12-month follow-up period. The system is considered to be suitable only for intermediate repairs of metal ceramic crowns that are in occlusal contact.

[Tooth replacement in the anterior region: specific problems and standard options]. / Tandvervanging in het front: specifieke problemen en standaardoplossingen.

The problems involved in the loss of anterior teeth differ essentially from those in the premolar/molar region. Firstly, missing anterior teeth result in unacceptable changes in appearance and speech, making treatment mandatory. Secondly, the dentist has to consider specific aspects, such as aesthetics, resorption of the alveolar bone, loading of the abutment teeth, form of the clinical crown and incisal guidance. Treatment options comprise orthodontic closure, periodontally supported removable and fixed appliances and appliances supported by implants. The advantages and disadvantages of the different options are indicated.

Clinical performance of resin-bonded bridges: a 5-year prospective study. Part III: Failure characteristics and survival after rebonding.

A total of 203 resin-bonded bridges were inserted under controlled clinical conditions and evaluated over a period of 5 years. During the evaluation period there were 47 dislodgements and 30 pontic fractures. The majority of the failures were retreated successfully. Dislodgement was in most cases due to fracture at the resin/retainer interface. The small number of fractures at the resin/tooth interface indicate that the clinical procedures, as used in this study, were satisfactory. Dislodged and rebonded resin-bonded bridges had a lower retention than original bonded bridges, indicating that patients with a dislodged bridge are a risk group for the retention of rebonded bridges. However, possible factors that may be responsible for this higher risk could not be demonstrated. The bridges which were removed for repair of the pontics and rebonded showed an acceptable retention. There was no relationship between the failure characteristic and the retainer type or the cementation material used.

Clinical performance of resin-bonded bridges: a 5-year prospective study. II. The influence of patient-dependent variables.

A total of 203 resin-bonded bridges was inserted under controlled clinical conditions and evaluated for a number of patient-dependent variables over a period of 5 years. Of the variables evaluated only 'initial occlusion of the abutment teeth' and 'location in the dental arch' had a significant influence on the retention of resin-bonded bridges. Anterior resin-bonded bridges were more durable than posterior bridges. Mandibular posterior bridges showed the lowest retention ratio. It is concluded that the design of posterior resin-bonded bridges should include tooth preparation or a wrap-around design of the retainers.

Clinical performance of resin-bonded bridges: a 5-year prospective study. I. Design of the study and influence of experimental variables.

A total of 203 resin-bonded bridges were inserted under controlled clinical conditions and evaluated over a period of 5 years. The study included two experiments to test the influences of retainer type, cementation material and operator on the success rate of resin-bonded bridges. The overall survival at 5 years was 75%. Micromechanical retainers were better than macromechanical retainers. For inserting micromechanical retainers, the cementation materials Clearfil F and Panavia Ex were better than Conclude. An operator effect was not found in this study.

The metal post and composite core combination.

Restoring broken down non-vital teeth implies in general the provision of a post and core foundation. Many materials and techniques have been introduced for this purpose in recent years. In this article the advantages and disadvantages of the cast and the non-cast post and core are discussed. The problems involved with the application of the post and core are reviewed. An efficient procedure for restoring a broken down tooth with a prefabricated post in combination with a composite core is presented.

Methodological aspects in clinical evaluation of cast restorations with colour slides.

In a methodological investigation colour slides were used for the clinical evaluation of crowns. Four criteria, described in a criteria list or recorded by means of reference slides, were used. In assessing the clinical characteristics of crowns to a certain extent colour slides turned out to be a useful instrument. Shortcomings of the method are discussed and improvements are suggested.