Biomedical subjects

D J Witter

Publications and source records attributed to D J Witter.

18 recordsLinked to original sources

PubMed1997

Dentists' attitudes to the shortened dental arch concept.

The aim of restorative dentistry in high-risk groups tends to shift over time from the preservation of complete dental arches towards the preservation of functional dental arches, using a functionally oriented approach. An example of this approach, aimed at limited treatment goals, is the shortened dental arch (SDA) concept. The objective of this study was to investigate dentists' attitudes to the SDA concept in general practice. A questionnaire seeking information pertaining to the attitudes and application of the SDA concept in clinical practice was sent to all dentally qualified members of staff in the field of restorative dentistry in the Nijmegen School of Dentistry (n = 64). From a 64% response, it was found that all but one of the respondents view the SDA concept as having a useful place in clinical practice. Although the respondents indicated only regular or occasional use of SDA in < 10% of patients, the outcome of SDA management was generally satisfactory or at least sufficient, notably in the care of special category patients. The findings support the view that the SDA concept has a role in contemporary clinical practice.

Attitude of Health Personnel↗

PubMed1997

Geroprosthodontics: The Nijmegen and Manchester Dental Schools approach.

If quality of care for elderly patients is to be achieved, thorough and realistic geroprosthodontic treatment planning is essential. This requires mature consideration, incorporating comprehensive patient assessment and selection of the most appropriate treatment option for each patient. The latter should be based on criteria which meet the demands of a healthy dentition and which enable a patient to achieve satisfactory oral function. The Nijmegen and Manchester Dental Schools have evolved simple patient-related treatment guidelines. These start with a problem-oriented approach which leads to a provisional treatment. The provisional treatment is intended to result in a healthy dentition that is monitored over an appropriate period. Evaluation of the provisional treatment leads to three options: extension of the monitoring time, preservation of the natural occlusion or loss of the natural occlusion. Definitive prosthodontic treatment plans are based on the second or third option. In the maintenance of good oral health after prosthodontic treatments, plaque and diet control are essential elements. Recall or maintenance programmes must be carried out if successful treatment is to be achieved and maintained.

Aged↗

PubMed1996

Yeast geranylgeranyltransferase type-II: steady state kinetic studies of the recombinant enzyme.

Rab proteins in mammalian cells, or Ypt1p and Sec4p in yeast, regulate vesicular traffic. Prenylation of these small GTP-binding proteins is required for membrane attachment and subsequent biological activity. Yeast protein geranylgeranyltransferase type-II (PGGTase-II) catalyzes the prenylation of Ypt1p in the presence of an escort protein, Msi4p. The genes encoding the alpha-(BET4) and beta-(BET2) subunits of PGGTase-II were translationally coupled by overlapping the BET4-BET2 stop/start codons and by adding a ribosome-binding site near the 3'-end of BET4 that fused an -EEF C-terminal alpha-tubulin epitope to Bet4p. Active recombinant heterodimer was purified by chromatography on DE52 and anti-alpha-tubulin columns. Recombinant Msi4p with an N-terminal polyhistidine leader was purified on a Ni(2+)-Sepharose column, followed by gel filtration and ion exchange chromatography. An escort protein, Msi4p, was necessary for geranylgeranylation of Ypt1p by yeast PGGTase-II. Michaelis constants for GGPP and Ypt1p were 1.6 and 1.1 microM, respectively; Vmax = 1.7 nmol min-1 mg-1 for yeast PGGTase-II. Typical Michaelis-Menten behavior was also seen for the enzyme for varied concentrations of Msi4p, with a maximal catalytic activity seen for a 10-fold excess of escort protein over enzyme. In contrast to previous reports, PGGTase-II requires both Zn2+ and Mg2+ for maximal activity, although Zn2+ becomes inhibitory at concentrations above approximately 10 microM. Prenylated Ypt1p obtained after incubation of Ypt1p with PGGTase-II, Msi4p, and geranylgeranyl diphosphate was digested with trypsin. The C-terminal peptide fragment from modified Ypt1p was purified by HPLC and analyzed by electrospray mass spectrometry. The mass of the fragment is consistent with the 12-mer C-terminal amino acid fragment predicted from proteolysis by trypsin with both cysteine residues modified by geranylgeranyl moieties.

Alkyl and Aryl Transferases↗

PubMed1995

The role of the shortened dental arch concept in the management of reduced dentitions.

Current research indicates that a more biological approach to dental care is required to cope with current trends in adult health and to make more efficient use of ever dwindling public financial resources. This paper describes the role of the shortened dental arch concept (SDA) in the management of reduced dentitions, including criteria for its application, possible indications and contraindications, and presents a review of research supporting SDA. In light of recent research, it is suggested that SDA will be of increasing importance as a treatment philosophy for the future elderly.

Aged↗

PubMed1994

A 6-year follow-up study of oral function in shortened dental arches. Part I: Occlusal stability.

In this clinical 6-year follow-up study subjects with shortened dental arches (SDA, n = 55), characterized by the absence of molar support, are compared with subjects with complete dental arches (CDA, n = 52) with respect to occlusal stability. In addition, a small group of subjects with SDA and removable partial dentures in the lower jaw (SDA+RPD, n = 19) is included in this study. The aim of this study was to describe effects regarding occlusal stability in subjects with SDA during a 6-year period. The applied parameters for occlusal stability are: number of occlusal contacts in the anterior region, overbite, interdental spacing and alveolar bone support. The results of this study show that: (i) SDA do provide durable occlusal stability; (ii) free-end RPD do not contribute to occlusal stability in SDA; and (iii) SDA with periodontally involved teeth show continuing periodontal breakdown.

Adult↗

PubMed1994

A 6-year follow-up study of oral function in shortened dental arches. Part II: Craniomandibular dysfunction and oral comfort.

In this clinical 6-year follow-up study subjects with shortened dental arches (SDA, n = 55), characterized by the absence of molar support, are compared with subjects with complete dental arches (CDA, n = 52) with respect to items concerning craniomandibular dysfunction and oral comfort. In addition, a small group of subjects with SDA and removable partial dentures in the lower jaw (SDA + RPD, n = 19) is included in this study. Oral comfort is defined using the following criteria: (i) absence of pain and distress, meaning the absence of signs and symptoms of craniomandibular dysfunction: (ii) chewing ability; and (iii) appreciation of the appearance of the dentition in relation to absent posterior teeth. Additionally, complaints about the free-end RPD are described. It is concluded that: (i) a SDA (consisting of 3-5 occlusal units, OU) is not a risk factor for CMD and is able to provide long-term sufficient oral comfort; and (ii) free-end RPD (in the lower jaw) in SDA do not prevent CMD and do not improve oral function in terms of oral comfort.

Adult↗

PubMed1993

Needs for tooth replacement.

The prime objective of dental care is maintaining a natural functional dentition for life. It is expected that a growing group of adults will keep their dentition into old age. Although routine prosthodontic care will still be important in the future the treatment strategy for older adults and elderly people with a reduced dentition does require a different approach. The traditional approach in prosthetic therapy was guided primarily by morphological criteria aimed at preservation of complete dental arches, which resulted in emphasis on quantity in dental care. Nowadays requirements such as aesthetics and functional comfort are considered more important and more easily achieved. In the presented principles for treatment planning the importance of a thorough preliminary treatment is stressed. Furthermore, needs for tooth replacement are discussed and guidelines are given for a preventive prosthodontic treatment approach in severely broken-down dentitions and edentulous patients.

Dental Prosthesis↗

PubMed1991

Shortened dental arches and periodontal support.

The periodontal support of subjects with shortened dental arches (SDA, n = 74), and of subjects with SDA and free-end removable partial dentures in the lower jaw (SDA and RPD, n = 25) was compared with that of subjects with complete dental arches (CDA, n = 72). The periodontal support was determined by tooth mobility and alveolar bone height, measured on a radiograph, of the distal alveolar bone of the premolars. Significant differences in tooth mobility were found between the three groups of subjects. The relative bone height showed a trend towards lower values for the SDA group and the SDA and RPD group. For some teeth these differences were significant. Premolars that are the most posteriorly located occluding teeth in the dental arch tend to have a lower relative alveolar bone height than premolars in an intermediate location. This effect is more marked in the upper jaw than in the lower jaw. Premolars in the lower jaw, that serve as abutment teeth for free-end RPDs, tend to show lower values for the relative bone height. It is concluded that the differences between the three groups with regard to the periodontal support are small. The large amount of crowns and bridges in both the SDA and SDA and RPD groups, and the dental history of these subjects, resulting in SDA, should be taken into account. However, as indicated by the periodontal breakdown of premolars in some subjects with SDA, the combination of an existing severe periodontal involvement and a SDA is considered to be an unfavourable situation.

Alveolar Bone Loss↗

PubMed1990

Shortened dental arches and masticatory ability.

In a previous study concerning oral function with shortened dental arches, it was found that approximately 10 per cent of the patients investigated complained of impaired masticatory ability despite a substantial reduction in arch length and, as a consequence, food platform area. This finding differs from those of studies relating masticatory performance to food platform area. From a review of pertinent literature, it is concluded that impairment of masticatory ability is manifest when less than 10 occluding pairs of teeth are present. Shortened dental arches are not associated with shifts in food selection adversely affecting general health.

Dental Arch↗

PubMed1990

Oral comfort in shortened dental arches.

In this study, the oral comfort was compared between subjects with shortened dental arches (SDA, n = 74), subjects with SDA and free-end removable partial dentures (SDA + RPD, n = 25) and subjects with complete dental arches (CDA, n = 72). Oral comfort was measured by (i) absence of pain or distress; (ii) chewing ability; (iii) appreciation of the appearance of the dentition. Additionally, the history of free-end RPD over a period of nearly 7 years was taken into consideration. On the whole, the results did not reveal any significant differences between the three groups with respect to pain or distress. Only 8% of the subjects with SDA reported impairment of chewing ability, and 11% had aesthetic complaints, due to missing posterior teeth in the upper jaw. Of the subjects with SDA + RPD, 20% had complaints about the RPD. In addition, the repeated necessity for repair or replacement of free-end RPD and the fact that some subjects (20%) stopped wearing the RPD during the observation period, confirm the poor performance of this dental provision. It is concluded that the oral comfort of subjects with SDA in this study is compromised to a small extent but remains on an acceptable level. Free-end RPDs do not appear to help oral comfort in these cases.

Adult↗

PubMed1989

The effect of removable partial dentures on the oral function in shortened dental arches.

In this study the effect of free-end removable partial dentures (RPD) on oral function was investigated by comparing subjects with shortened dental arches (SDA, n = 55) and a group of subjects with SDA and RPD (n = 25). In addition, a group of subjects were selected who had worn an RPD in the past (n = 19). All subjects had a remaining natural dentition consisting of an intact front region and three to five occlusal units (OU) in the posterior area. On the whole, subjects with RPD had less natural OU compared with subjects without RPD. However, this is also true for those who had worn an RPD in the past. The oral functions of subjects with SDA did not differ significantly when compared with subjects with SDA and RPD. Significantly more subjects who had an RPD in the past reported a limited mobility of the mandible, an impaired chewing capacity and chewing with the front teeth. They also reported more aesthetic complaints due to missing posterior teeth. It is concluded that within the populations investigated in this study oral function is not evidently improved by the insertion of a free-end RPD.

Adult↗

PubMed1988

Signs and symptoms of mandibular dysfunction in shortened dental arches.

In this study subjects with shortened dental arches (SDA, n = 60), characterized by the absence of molar support, are compared with subjects with a complete dentition (n = 72) with respect to signs and symptoms of mandibular dysfunction. The subjective examination consisted of questions related to pain, noises within the joints and mobility of the lower jaw. The objective examination consisted of the registration of clicking of the temporomandibular joint (TMJ) by bilateral palpation and measuring the maximal mouth opening. In spite of the finding that significantly more subjects of the SDA group under 40 years of age reported pain in or around the TMJ, it is concluded that in the population studied no convincing evidence was found that a SDA provokes signs and symptoms of mandibular dysfunction.

Adult↗

PubMed1987

Migration of teeth in shortened dental arches.

In shortened dental arches (SDA) the remaining premolars tend to migrate distally. This may lead to a decrease of the vertical dimension, resulting in an increased load on the anterior teeth. Consequently the number and intensity of the occlusal contacts between the front teeth increase. This may result in interdental spacing in the upper front region. In this study the pattern of migration of the teeth in subjects with SDA (n = 60) is described. The SDA group is compared with subjects having complete dental arches (n = 72). Although a systemic effect of SDA has been found on interdental spacing for subjects under 40 years of age, it is concluded that this migration is within acceptable levels.

Adult↗

PubMed1987