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Biomedical subjects

J D Walter

Publications and source records attributed to J D Walter.

At least 19 recordsLinked to original sources
PubMed2006

Impact of wearing an intra-oral lubricating device on oral health in dry mouth patients.

OBJECTIVE: To establish whether an intra-oral lubricating device for dry mouth alters the oral environment. DESIGN: A single-blind randomized cross-over study. METHOD: Twenty-nine dentate subjects from the Sjogren's syndrome clinic attended on five occasions at 4-week intervals. They were randomized, having the device fitted on either the second or the fourth visit for the experimental period, whilst using their preferred method of lubrication throughout the rest of the study. The preferred methods of lubrication were either water (group 1, n = 10) or saliva substitute (group 2, n = 9) or sugar-free chewing gum (group 3, n = 10). At each visit microbiological, unstimulated and stimulated saliva samples were collected. Dry mouth score, speech test and periodontal indices were recorded. RESULTS: The water lubrication group (1) had a resting salivary flow greater than lubrication groups (2 and 3) by post-ANOVA contrasts (P < 0.001). The postdevice data also demonstrated a salivary flow greater than lubrication group (3) by post-ANOVA contrasts (P < 0.05). The epithelial cell count using the Spearman correlation was high, possibly reflecting increased viscosity of the saliva (P = 0.044). The speech test indicated that the experimental subjects had difficulty in speaking (P = 0.001). This was slightly easier postdevice wear. Streptococcus mutans (P = 0.009) and Lactobacillus (P = 0.058) increased in the saliva after wearing the device. Salivary flow rate, Candida albicans, oral dryness, speaking and periodontal indices were unchanged. CONCLUSIONS: The oral environment was altered by wearing a lubricating device with an increase in the numbers of Strep. mutans and Lactobacillus. Clinical dryness and speech test correlated with the mean whole salivary flow suggesting a screening method for xerostomia.

Adult↗
PubMed2002

Patient preferences in a preliminary study comparing an intra-oral lubricating device with the usual dry mouth lubricating methods.

OBJECTIVE: To compare an intra-oral device to relieve oral dryness with the other methods of lubricating the mouth at night. DESIGN: Multidisciplinary single blind randomised cross over study. SETTING: The subjects were drawn from patients attending a dry mouth clinic. MATERIALS AND METHODS: Thirty-four dentate subjects attended on five occasions at intervals of 4 weeks. At the first visit the teeth were scaled and impressions were recorded. The device was fitted either on the second or the fourth visit. At all visits samples were taken of the resting and stimulated saliva for volumetric analysis and the dry mouth score recorded. Data were collected from the lubrication timings and the questionnaire. RESULTS: Ten water, nine saliva substitute and ten sugar-free chewing gum lubricators completed the study. There were 27 female and two male subjects with an average age of 62 years. Nine out of 10 of those lubricating with chewing gum preferred wearing the device (P = 0.037). After the device wearing period the subjects' self assessment of mouth dryness (P = 0.056), speech (P = 0.009) and swallowing (P = 0.031) were more favourable when compared with the alternative lubrication with 66% preferring the intra-oral device to their alternative method of lubrication. CONCLUSIONS: The majority of the subjects preferred wearing the device at night compared with their normal method of lubrication. Subjects' perception of dryness, speech and swallowing became closer to the clinician's assessment after wearing the device.

Adult↗
PubMed2000

An investigation of factors influencing patients' use of new complete dentures using structural equation modelling techniques.

UNLABELLED: A review of the literature demonstrated that research had not identified a set of prognostic indicators for prospective complete denture patients, with different authors publishing contradictory results. OBJECTIVE: To investigate possible relationships between patient and clinical factors and denture wear and use of dentures for eating. METHODS: Patients attending Guy's Dental Hospital, London, for provision of complete dentures were recruited. For each patient relevant history was recorded and an examination of the edentulous mouth and existing dentures, where present, was undertaken at the beginning of treatment. At the first post-insertion appointment the edentulous mouth, previous and new dentures were examined. Three months after the review appointment patients were sent a postal questionnaire to assess patient use of dentures and patient satisfaction. Data were analysed using structural equation modelling techniques. RESULTS: 723 patients were recruited. Significant relationships were found between quality of complete dentures and patients' use of complete dentures and between quality of residual edentulous ridges and patients' use of complete dentures. These results contrast with most previous research into prognostic indicators for success in complete denture treatments. CONCLUSIONS: Quality of residual edentulous ridges and quality of new complete dentures predict patients' use of new complete dentures.

Aged↗
PubMed1999

Exercise testing: improving performance with a ramped Bruce protocol.

BACKGROUND: The standard Bruce protocol was compared with a ramped Bruce protocol in stress testing of a general population of patients. METHODS: We examined hemodynamic responses, test duration, and patient comfort with each exercise protocol. Twenty-three patients completed the study, 14 men and 9 women with a mean age of 51 +/- 12 years. Each patient completed the 2 treadmill protocols in a random manner. RESULTS: Mean peak heart rate, systolic blood pressure, and rating of perceived exertion according to the revised Borg scale were equivalent in both protocols, measuring 157 +/- 15 beats/min, 170 +/- 22 mm Hg, and 8 +/- 1 for the Bruce and 158 +/- 17 beats/min, 175 +/- 20 mm Hg, and 8 +/- 1 for the ramp protocol (P = NS). Duration of test and metabolic equivalents (METs) were greater with the ramp than with the Bruce protocol. For the Bruce duration and METs were 8:25 +/- 3:00 min and 9.6 +/- 3.1, and for the ramp 10:01 +/- 2:32 min and 11.4 +/- 2.7 (P <.0001 for both). Subjective rating of difficulty was assessed on a scale of 1 to 5, 1 being the most difficult and 5 being the easiest. Rating for the Bruce protocol was 2.5 +/- 0.9 and for the ramp 4.1 +/- 0.9 (P <.0001). CONCLUSION: We propose that a ramped modification of the Bruce protocol achieves equivalent hemodynamic goals but with better duration. Patients preferred the ramp with respect to comfort, and exercise data can be correlated easily with standard protocols.

Adult↗
PubMed1999

Association between the accuracy of intermaxillary relations and complete denture usage.

STATEMENT OF PROBLEM: Previous studies have investigated possible associations between the accuracy of intermaxillary relations and complete denture usage with variable results. PURPOSE: This study investigated the association between the intermaxillary relations in new complete dentures and the use of these dentures for daily wear and eating. METHODS: A prospective study of patients (n = 523) attending Guy's Dental Hospital for complete dentures was undertaken. Patients were examined at the beginning of treatment and at the first post insertion visit. Rest vertical dimension and vertical dimension of occlusion were measured with a Willis gauge. Quality of registration of centric relation position was assessed and, 3 months later, a postal questionnaire was sent to investigate patients' use of dentures. Data were analyzed with Pearson's chi-squared test with exact nonparametric inference. RESULTS: Adequate interocclusal rest space was associated with daily wear of dentures (chi2 = 7.97, P =. 018). Quality of registration of centric relation was associated with daily wear (chi2 = 32.43, P <.001) and use of dentures for eating (chi2 = 20.23, P =.003). CONCLUSION: Positive associations were found between the accuracy of intermaxillary relations and complete denture usage.

Aged↗
PubMed1999

Denture plaque and adherence of Candida albicans to denture-base materials in vivo and in vitro.

The aim of this paper is to review our understanding of the mechanisms and clinical significance of adhesion of C. albicans to denture-base materials in relation to denture plaque and denture-related stomatitis. Earlier reports in the literature of a 65% prevalence level of denture-related stomatitis seem to be exaggerated. More recent studies indicate that denture-related stomatitis is considerably less common, particularly in normal healthy subjects. The etiology of the condition is discussed in this review, and although much of the literature supports the view that the condition is strongly associated with C. albicans, this is not always so. In some subjects, the cause appears to be related to a non-specific plaque. This review also considers the role of denture plaque in the pathogenesis of denture-related stomatitis, the sequential development of denture plaque, and its colonization by Candida organisms. Designing controlled in vivo studies is difficult, and as a consequence, many investigators have had to resort to in vitro studies. The majority of these studies have attempted to investigate the hydrophobicity of C. albicans, relating the surface free-energy of denture-base materials, particularly acrylic resin, to that of the organism. Surprisingly little work has been directed at surface roughness and how it affects retention of organisms. Further, no attention has been paid to the properties and character of the surface, other than average surface roughness, as it affects adhesion. A comparison of results from in vitro studies on the effect on adhesion of pre-coating the surfaces of denture-base materials with saliva has produced equivocal conclusions. This is largely due to little standardization of experimental protocols between studies, particularly in the collection and handling of the saliva used. In conclusion, the review strongly supports the suggestion that adherence of C. albicans to denture-base materials in vitro is related to the hydrophobicity of the organism. The clinical significance of the observation and the mechanisms for the development and maturation of denture plaque are yet to be understood. There is a clear need for further investigation of other factors that may moderate the adhesion of organisms and subsequent colonization of denture-base materials.

Acrylic Resins↗
PubMed1999

Operator agreement in the use of a descriptive index of edentulous alveolar ridge form.

CAWOOD & HOWELL have proposed a classification of the anatomical form of the residual alveolar processes of edentulous patients. The purpose of this study was to test observer agreement in the clinical assessment of edentulous alveolar ridge form using this classification. This was tested in a pilot study involving 57 edentulous patients, and subsequently in a study of 557 edentulous patients. High levels of observer agreement were found when using this classification for upper and lower edentulous alveolar ridges, suggesting that the classification may be useful as a research tool.

Alveolar Bone Loss↗
PubMed1999

Comparison of patients' appreciation of 500 complete dentures and clinical assessment of quality.

To compare patients' appreciation and clinical assessment of quality of complete dentures 500 patients attending a dental teaching hospital for provision of new complete dentures were recruited. In each case denture quality was assessed by an experienced prosthodontist using a validated classification of aspects of denture quality. Patients graded their appreciation of features of the dentures on a four point scale. Multiple correspondence analysis demonstrated close correspondence between dentist and patient appreciation of dentures when the dentures were rated as poor, but little or no correspondence when dentists or patients rated the dentures highly.

Attitude of Health Personnel↗
PubMed1998

Adherence of Candida albicans to denture-base materials with different surface finishes.

OBJECTIVES: To assess the in vitro adherence of Candida albicans to heat-cured hard and soft denture-base materials with varying surface roughness, and to observe the effect of a mixed salivary pellicle on candidal adhesion to these surfaces. METHODS: In vitro adhesion assays on heat-cured acrylic resin (Trevalon), Molloplast B and Novus using the type strain of C. albicans (NCPF 3153A). Surfaces for the assays were prepared using clinically appropriate rotary instruments. Unstimulated, pooled and clarified whole saliva was used to assess its effect on adhesion. RESULTS: Significantly greater adhesion of C. albicans to rough rather than smooth surfaces was found (P < 0.001), as well as increased adhesion to the machined soft lining materials compared with acrylic. Pre-coating denture-base materials with saliva reduced candidal adhesion on all materials. CONCLUSIONS: Rough surfaces on denture-base materials promote the adhesion of C. albicans in vitro. However, saliva reduces adhesion of C. albicans and thus diminishes the effect of surface roughness and free surface energy differences between materials.

Acrylic Resins↗
PubMed1998

Factors associated with the presence of denture related stomatitis in complete denture wearers: a preliminary investigation.

Various factors have been associated with the presence of denture related stomatitis. These include local factors such as continuous denture wear, trauma from dentures and poor denture hygiene Systemic factors, use of various pharmacological agents and smoking have also been implicated. This investigation involved history taking and examination of 250 patients attending Guy's Hospital for the construction of complete dentures. No association was found between systemic factors, use of pharmacological agents or smoking and the presence of denture related stomatitis. Night wear of complete dentures was found to be significantly associated with the prevalence of denture related stomatitis.

Chi-Square Distribution↗
PubMed1997

The effects of surface machining on heat cured acrylic resin and two soft denture base materials: a scanning electron microscope and confocal microscope evaluation.

STATEMENT OF PROBLEM: Rough surfaces promote the adhesion and colonization of denture plaque, therefore it is important to know the character of the surface left by rotary instruments on denture base materials. As a single microscopic technique can introduce artifact, complementary microscope techniques need to be used. PURPOSE: This study investigated the surface characteristics of the machined surfaces of heat-cured acrylic resin, Molloplast B and Novus. MATERIAL AND METHODS: Scanning electron microscopy and confocal microscopy were used to investigate surfaces that had been prepared with appropriate clinical rotary instruments. Thirty samples of each material were prepared with steel and tungsten carbide burs, Molloplast stones, and Arbor bands. An analysis of variance, with the Scheffe multiple comparison of means test, was used to compare average surface roughness of the individual surfaces. RESULTS: The tungsten carbide bur produced a smoother nongrooved surface than the steel bur on acrylic resin. The roughest surfaces were produced on the soft lining materials by the Arbor band and Molloplast stone. CONCLUSIONS: The confocal microscope is a valuable complementary instrument to scanning electron microscopy and provides surface roughness data by using a noncontact method. Each type of rotary instrument produces its own characteristic surface on denture base materials.

Acrylic Resins↗
PubMed1997

An investigation of debonding between heat-cured PMMA and titanium alloy (Ti-6A1-4V).

OBJECTIVES: The bonding of acrylic resin to dental prostheses constructed from metal has been the subject of extensive research in recent years, much of it between base-metal alloys such as Ni-Cr alloys and dental composite. The development of techniques for the manufacture of dental appliances from titanium and titanium alloys has opened new avenues for investigation of the metal/acrylic resin bond. METHODS: In this study, a bond strength comparison between two PMMA products, Trevalon and Metadent, and discs of titanium alloy, Ti-6A1-4V, was investigated using a four-point bend test configuration. Trevalon is a standard, commercially available, heat-cured acrylic resin, while Metadent is an acrylic resin incorporating a chemical bonding agent, 4-META. A comparison was made between two processes that are routinely used to enhance the bond between metal and acrylic, namely sandblasting of the metal surface and using the Silicoater system following sandblasting. Each of the samples was paired, thus allowing a further comparison to be made between samples that had undergone thermocycling in a water bath, with those that had been held at a constant temperature. RESULTS: The study revealed that a superior metal/acrylic bond was achieved by the use of the silicoating system when either Trevalon or Metadent was used both before and after thermocycling. Reduced debonding loads were recorded for all samples that had undergone thermocycling. CONCLUSIONS: Highest bond strengths were recorded for Trevalon or Metadent processed against a silicoated Ti-alloy surface.

Acrylic Resins↗
PubMed1997

Scanning electron microscopy of the development of structured aerial mycelia and satellite colonies of phenotypically switched Candida albicans.

Candida albicans is an asexual diploid fungus that can express high frequency phenotypic switching. Switched variants can develop structured aerial mycelia (SAM) and cultures that have been grown for a protracted period exhibit satellite colonies. This study investigated the development of both SAM and satellite colonies by means of a freeze-drying technique and scanning electron microscopy. The results show that SAM may develop due to hyphae developing in the colony at the base of the structures. The development of satellite colonies is a result of cells that have grown deep into the agar re-emerging on to the agar/air surface and producing a new colony. Although both SAM and satellite colonies are often seen together on mature colonies, their cause and development are different.

Candida albicans↗
PubMed1997

Exercise-induced ventilatory abnormalities in orthotopic heart transplant patients.

STUDY OBJECTIVE: The purpose of this investigation was to compare multiple ventilatory responses of heart transplant patients (HTP) with normal subjects (NL) at rest, at absolute and relative submaximal exercise levels, and at peak exercise. DESIGN: Ten male HTP and 10 matched NL were tested under similar conditions on a treadmill with the use of an incremental protocol to symptom-limited maximal levels while breath-by-breath measurements of gas exchange and ventilation were obtained. RESULTS: At an absolute carbon dioxide (VCO2) level of 1 L.min-1, minute ventilation (VE) was significantly higher in HTP compared with NL (38.4 +/- 1.9 versus 29.3 +/- 0.9 L.min-1). However, when compared at similar relative levels (i.e., 40% and 60% of the peak oxygen consumption [VO2 peak]), VE was found to be significantly higher in NL compared with HTP (25.5 +/- 1.4 versus 21.2 +/- 1.0 L.min-1 at 40%; 39.9 +/- 3.1 versus 32.1 +/- 2.0 L.min-1 at 60%, respectively). The reduced VE was the result of a significantly lower tidal volume (VT) in HTP compared with NL at 40% (1.14 +/- 0.08 versus 1.33 +/- 0.05 L) and 60% (1.40 +/- 0.10 versus 1.85 +/- 0.06 L) of VO2 peak, since breathing frequency (BF) was not different between the groups at these levels. CONCLUSIONS: These data demonstrate that HTP have abnormal ventilatory responses to incremental exercise that are largely explained by a diminished VT response. While mechanical factors known to affect VT cannot be ignored, it is likely that the abnormal VT response of HTP during exercise is secondary to respiratory muscle weakness and may be due to hypoperfusion, long-term deconditioning, and/or the long-term use of corticosteriods.

Adult↗
PubMed1996

New design for an artificial saliva reservoir for the mandibular complete denture.

Wearing dentures can be an extremely uncomfortable experience for people with xerostomia. Despite several ingenious designs, the problem of combining saliva substitutes with a simple, effective, and readily cleanable dispensing system has not been satisfactorily resolved. The previous difficulties were analyzed and methods of overcoming them were devised. A new design for a reservoir denture is presented that maximizes capacity and is easily maintained by the wearer.

Denture Design↗
PubMed1995

Occlusal variables, bruxism and temporomandibular disorders: a clinical and kinesiographic assessment.

Seventy-five patients suffering from myofascial pain, headaches and anterior disc displacement were assessed clinically and with a kinesiograph. Twenty-eight asymptomatic dental staff served as a control group. The prevalence of awareness of bruxism was significantly greater in our TMD patients than the controls. Bruxism patients recorded a higher prevalence of incisor dentine wear suggestive of a forward mandible posture. Class II, Division 1 malocclusions formed a significantly higher proportion of the TMD patient group than the controls. Kinesiographic recordings showed that the vertical and lateral components of movement from postural position to intercuspal were significantly greater in the patient group.

Adolescent↗