Biomedical subjects

R J Crisp

Publications and source records attributed to R J Crisp.

17 recordsLinked to original sources

PubMed2005

Two-year evaluation of restorations of a packable composite placed in UK general dental practices.

OBJECTIVE: The aim of this study was to assess the clinical performance at two years of 100 Solitaire 2 restorations placed in five United Kingdom dental practices by members of a practice-based research group. METHOD AND MATERIALS: Restorations were assessed after two years by a trained evaluator and the dental practitioner who had placed the material, for anatomic form, marginal adaptation, surface roughness, gingival condition and the presence or absence of secondary caries. In addition, the patients completed a questionnaire requesting details of the comfort and performance of the Solitaire 2 restoration(s). RESULTS: A total of 88 (58 Class II and 30 Class I) restorations of Solitaire 2 placed in 49 patients (mean age 43 years) were assessed. Twelve restorations could not be evaluated because of patient unavailability for the dates of the examinations. Two Class II restorations (2%) had failed by the time of the two-year evaluation and the remaining 86 restorations were found to be intact with no secondary caries. A high percentage of optimal scores were recorded for anatomic form and surface roughness. The colour match of two restorations (2%) was recorded as an obvious mismatch, but otherwise no unacceptable scores were recorded. CONCLUSIONS: After two years of clinical service a high proportion (96%) of the Solitaire 2 restorations that were available for re-examination, placed in general dental practice settings, were found to be performing satisfactorily.

Adhesives↗

PubMed2005

Conducting trials.

Explore the source record for details and available documents.

Clinical Trials as Topic↗

PubMed2002

Research in dental practice: a 'SWOT' analysis.

Most dental treatment, in most countries, is carried out in general dental practice. There is therefore a potential wealth of research material, although clinical evaluations have generally been carried out on hospital-based patients. Many types of research, such as clinical evaluations and assessments of new materials, may be appropriate to dental practice. Principal problems are that dental practices are established to treat patients efficiently and to provide an income for the staff of the practice. Time spent on research therefore cannot be used for patient treatment, so there are cost implications. Critics of practice-based research have commented on the lack of calibration of operative diagnoses and other variables; however, this variability is the stuff of dental practice, the real-world situation. Many of the difficulties in carrying out research in dental practice may be overcome. For the enlightened, it may be possible to turn observations based on the volume of treatment carried out in practice into robust, clinically related and relevant research projects based in the real world of dental practice.

Attitude of Health Personnel↗

PubMed2001

Multiple identities in Northern Ireland: hierarchical ordering in the representation of group membership.

A study was conducted to explore whether participants in Northern Ireland attend to, and process information about, different group members as a function of a single dimension of category membership (religion) or as a function of additional and/or alternative bases for group membership. Utilizing a bogus 'newspaper story' paradigm, we explored whether participants would differentially recall target attributes as a function of two dimensions of category membership. Findings from this recall measure suggested that information concerning ingroup and outgroup members was processed as an interactive function of both religion and gender intergroup dimensions. Religion was only used to guide processing of more specific information if the story character was also an outgroup member on the gender dimension. These findings suggest a complex pattern of intergroup representation in the processing of group-relevant information in the Northern Irish context.

Adult↗

PubMed2001

Wastage of a silicone impression material in a general practice setting: a comparison between hand and automixing methods.

A practice-based, randomised, controlled trial has been undertaken to investigate the wastage of impression material when recording full arch one-stage, polyvinyl siloxane impressions using four techniques: putty and automix light viscosity material, putty and automix regular viscosity material, putty and tubed light viscosity material, and putty and tubed regular viscosity material. A total of 100 maxillary impressions, comprising 25 recorded using each of the four techniques, were obtained according to a predetermined scheme for randomisation. All material wasted in dispensing, mixing and applying each impression was determined by repeated weighing. Statistical comparisons of the mean weights of material wasted for each type of impression revealed that significantly (P < 0.01) less wastage occurred with the automix techniques. It is concluded that automix impression techniques may, in more extensive studies, be found to be more cost effective than tubed impression material techniques when recording impressions of the type investigated.

Cost-Benefit Analysis↗

PubMed2001

One-year retrospective clinical evaluation of hybrid composite restorations placed in United Kingdom general practices.

OBJECTIVE: The purpose of this study was to assess Pertac II restorations placed in general dental practice. METHOD AND MATERIALS: A total of 86 restorations (14 Class I, 10 Class II, 17 Class III, 5 Class IV, and 40 Class V) using a hybrid composite material (Pertac II) placed in 56 patients (mean age, 39 years) in 5 dental practices in the United Kingdom were assessed after 1 year by a trained evaluator and the dental practitioner who had placed the restoration. All the restorations were assessed for anatomic form, marginal adaptation, surface roughness, sensitivity or discomfort, gingival condition, and the presence or absence of secondary caries. RESULTS: Thirty-five (43%) restorations were placed in load-bearing situations, 9% of which were assessed as being in "heavy" occlusion. Five (6%) of the restorations were lost (all Class V restorations), 4 from premolars and 1 from a molar. Four were in wedge-shaped cavities and 1 small restoration was actually dislodged during examination. The remaining 81 (94%) restorations were found to be intact, with no secondary caries detected. A high percentage of optimal scores were recorded for both anatomic form and surface roughness. CONCLUSION: It is concluded that the evaluation demonstrated satisfactory clinical performance of Pertac II restorations after 1 year of clinical service in the wide variety of clinical situations seen in general dental practice. However, the potential for failure of hybrid composite materials in Class V situations appears high. It may be argued that clinicians who wish to use a resin-based material in a Class V situation should use a compomer or microfilled composite.

Adult↗

PubMed2000

Roles of the heparin and low density lipid receptor-related protein-binding sites of protease nexin 1 (PN1) in urokinase-PN1 complex catabolism. The PN1 heparin-binding site mediates complex retention and degradation but not cell surface binding or internalization.

We have previously described thrombin (Th)-protease nexin 1 (PN1) inhibitory complex binding to cell surface heparins and subsequent low density lipid receptor-related protein (LRP)-mediated internalization. Our present studies examine the catabolism of urinary plasminogen activator (uPA)-PN1 inhibitory complexes, which, unlike Th.PN1 complexes, bind almost exclusively through the uPA receptor. In addition, the binding site in PN1 required for the LRP-mediated internalization of Th.PN1 complexes is not required for the LRP-mediated internalization of uPA.PN1 complexes. Thus, the protease moiety of the complex partially determines the mechanistic route of entry. Because cell surface heparins are only minimally involved in the binding and internalization of uPA.PN1 complexes, we then predicted that complexes between uPA and the heparin binding-deficient PN1 variant, PN1(K7E), should be catabolized at the same rate as complexes formed with native PN1. Surprisingly, the uPA.PN1(K7E) complexes were degraded at only a fraction of the rate of native complexes. Internalization studies revealed that both uPA. PN1(K7E) and native uPA.PN1 complexes were initially internalized at the same rate, but uPA.PN1(K7E) complexes were rapidly retro-endocytosed in an intact form. By examining the pH dependence of complex binding in the range of 4.0-7.0, it was determined that the uPA.PN1 inhibitory complexes must specifically bind to endosomal heparins at pH 5.5 to be retained and sorted to lysosomes. These studies are the first to document a role for heparins in the catabolism of SERPIN-protease complexes at a point further in the pathway than cell surface binding, and this role may extend to other heparin-binding LRP-internalized ligands.

Amyloid beta-Protein Precursor↗

PubMed2000

Treatment of dentinal hypersensitivity using a dentine bonding system.

AIMS AND OBJECTIVES: Many agents have been used in treatment of dentinal hypersensitivity in the past, but dentine bonding systems have recently been suggested as being effective. This study examined the effectiveness of a dentine bonding system in the treatment of dentinal hypersensitivity in dental practice conditions. METHODS: Dentists in two dental practices agreed to carry out the project. One practice was in the UK, the other in India. A total of 34 patients who were diagnosed to have dentinal hypersensitivity were treated using the dentine bonding system. Patients were requested to record their perception of their pain on a 100mm linear scale, pre-treatment, one day and one week post-treatment. RESULTS: All patients experienced relief of pain, both 1 day and 1 week after treatment. Profile plots of the patients' perceived pain scores for the two practices separately indicated that there was a general trend across both practices for these to fall quite sharply one day after treatment and then generally level out one week post-treatment. There was evidence indicating a possible difference in pain perception in the two communities from which the patients were drawn. CONCLUSION: The dentine bonding system evaluated was successful in reducing the pain of dentinal hypersensitivity, at least in the short term.

Analysis of Variance↗

PubMed2000

One-year clinical evaluation of compomer restorations placed in general practice.

OBJECTIVE: This study evaluated the in-service performance, after 1 year, of a sample of F2000 compomer restorations placed by 10 general dental practitioners as part of handling evaluation of this material. METHOD AND MATERIALS: Five general dental practitioners who participated in the handling evaluation were asked to cooperate in the 1-year assessment of the restorations. The practitioners were requested to contact patients and inquire if they were willing to attend at a specified time for examination of their restorations by a trained evaluator who would travel to the various practice locations. A total of 84 restorations were presented for examination. The mean age of the restorations at examination was 14 months. The restorations were assessed for anatomic form, marginal adaptation, surface roughness, sensitivity or discomfort, gingival condition, and presence or absence of secondary caries. RESULTS: Eighty-two restorations were intact. No secondary caries was detected. Optimal scores were obtained in a high proportion of the assessments. All patients reported satisfaction with the restorations, both in appearance and surface texture, and no symptoms were reported. CONCLUSION: The F2000 compomer restorations, placed in conjunction with its bonding system in general practice conditions, were found to be performing satisfactorily after 1 year.

Adult↗

PubMed2000

A clinical evaluation of Class II composites placed using a decoupling technique.

PURPOSE: This study was undertaken to evaluate the three-year clinical performance of Class II restorations of a fine particle hybrid composite placed using a decoupling placement technique, whereby polymerization shrinkage stresses at the cervical tooth-restoration interface were minimized by separating the initial gingival increment of composite from the body of the restoration using a polyurethane varnish. MATERIALS AND METHODS: The study was a practice-based explanatory, single-center clinical trial. A minimum of 40 Class II restorations of the material under investigation (Tetric) was required to be placed in predominantly molar teeth in selected patients. The restorations were placed using a decoupling incremental technique, bonding being accomplished using Syntac and Heliobond. The restorations were reviewed within 1 month of placement, thereafter at 18 months, then at 2 and 3 to 4 years using predetermined codes and criteria. Impressions and photographic records were used to obtain retrospective, third-party assessments of the restorations. RESULTS: Of 43 restorations originally placed and found to have ideal characteristics at baseline review, 41 (95%) were reviewed at 18 months, 36 (84%) at two years, and 31 (74%) at 3 to 4 years. None of the restorations were found to have suffered significant deterioration, notwithstanding three restorations having been lost to the study because of the replacement of part of the restored tooth for causes other than the catastrophic failure of the material. No secondary caries or postoperative sensitivity was recorded. CONCLUSION: It was concluded that the findings support the use of the material under investigation in the restoration of moderate- to large-sized Class II preparations in selected patients. The decoupling placement technique employed may be found to be an effective means to limit postoperative sensitivity and to contribute to the favorable in-service performance of restorations of the type investigated. Good practice would now require a multicentered, randomized controlled trial to investigate the effectiveness of the material and, in particular, the decoupling technique under the conditions of everyday practice.

Acrylates↗

PubMed1999

Analysis of a structural determinant in thrombin-protease nexin 1 complexes that mediates clearance by the low density lipoprotein receptor-related protein.

We recently identified a synthetic peptide, Pro47-Ile58, derived from the mature protease nexin 1 (PN1) sequence, that inhibited the low density lipoprotein receptor-related protein (LRP)-mediated internalization of thrombin-PN1 (Th-PN1) complexes. Presently, we have analyzed this sequence in Th-PN1 complex catabolism using two independent approaches: 1) An antibody was generated against Pro47-Ile58, which inhibited complex degradation by 70% but had no effect on the binding of the complexes to cell surface heparins. This places the structural determinant in PN1 mediating complex internalization by the LRP outside of the heparin-binding site. 2) Site-directed genetic variants of PN1 with a single Ala substitution at His48, or two Ala substitutions, one at His48 and another at Asp49, were expressed in Sf9 insect cells. The catabolic rate of complexes formed between Th and the singly substituted and doubly substituted variants was lowered to 50 and 15%, respectively, when compared with the catabolic rate of native Th-PN1 complexes. This is the first analysis of a structural determinant in a serine protease inhibitor (SERPIN) required for LRP-mediated internalization and in part may explain the cryptic nature of this site in the unreacted serine protease inhibitor.

Amino Acid Sequence↗

PubMed1999

Upper extremity augmentation of lower extremity kinetics during countermovement vertical jumps.

Twenty-five volleyball players (14 males, 11 females) were videotaped (60 Hz) performing countermovement vertical jumps with and without an arm swing. Ground reaction force and video-based coordinate data were collected simultaneously. The resultant joint force and torque at the hip, knee, ankle and shoulder for two trials per subject per condition were computed and normalized. Average kinematic, resultant joint force and torque data were compared using repeated-measures analysis of variance. Larger values were recorded for the vertical velocity of the centre of mass at take-off in the jumps with (mean 2.75, s = 0.3 m.s-1) versus without (mean 2.44, s = 0.23 m.s-1) an arm swing. The jumps with no arm swing produced larger torques at the hip during the first third of the propulsive phase (from zero to maximum vertical velocity of the centre of mass). During the final two-thirds of the propulsive phase, the arm swing augmented hip extensor torques by slowing the rate of trunk extension and placing the hip extensor muscles in slower concentric conditions that favoured the generation of larger forces and resultant joint torques. During the first two-thirds of the propulsive phase, knee extensor torque increased by 28% in the jumps with an arm swing, but maintained a relatively constant magnitude in the jumps with no arm swing.

Adult↗

PubMed1999

A short-term clinical evaluation of a tricure glass-ionomer system as a transitional restoration and core buildup material.

OBJECTIVE: A general dental practice study investigated the use of a resin-modified glass ionomer material as a transitional restoration and as a core buildup material. The study also assessed a resin-modified glass-ionomer luting system. METHOD AND MATERIALS: Fifty-one badly broken-down vital permanent molar teeth in 44 patients were restored. No dentin pins were placed; however, preexisting pins were retained in 7 teeth. Following baseline and 3-month assessments, complete veneer gold crowns were placed on the selected teeth. The preparations involved ferruling in sound tooth tissue. The completed crowns were reviewed 3 and 12 months after placement. Modified US Public Health Service criteria were used for assessment throughout. Clinical assessment was complemented by examination of photographic records and replicas obtained from silicone impressions. RESULTS: All 51 transitional restorations were found to be clinically satisfactory at the 3-month review. Nineteen (37%) transitional restorations had limited defects that were eliminated in crown preparation. Of the 51 permanent crowns, 46 (90%) were reviewed at 3 months and 44 (86%) at 1 year. All the crowns reviewed at 3 and 12 months were clinically satisfactory. The luting system investigated showed favorable handling characteristics and excellent short-term performance. CONCLUSION: The materials investigated are, over a period of at least 12 months, effective in the restoration of broken-down molar teeth destined to be crowned. With the use of these materials and ferruling, the use of dentin pins may be unnecessary in selected cases.

Adolescent↗

PubMed1998

Evaluation of the handling of a new compomer and novel dispensing system in general dental practice.

OBJECTIVE: Easy handling of materials is essential to the production of good clinical results. The handling properties of a new compomer material and its novel primer/adhesive-dispensing system were tested in clinical use. METHOD AND MATERIALS: Ten general dental practitioners used the new material and dispenser for 3 weeks and completed a questionnaire regarding the handling, esthetics, and ease of use. They were asked to compare the new material to the compomer, resin composite, and glass-ionomer materials normally used in their own practice. RESULTS: The material scored a mean of 4.4 for dispensing convenience on a linear scale of 1 (inconvenient) to 5 (convenient) and 4.6 for ease of use (5 = easy to use, and 1 = difficult to use). The dispensing system achieved a high rating of 4.9 for convenience (5 = convenient, and 1 = inconvenient). CONCLUSION: The new material received ratings that were superior to those of the glass-ionomer and compomer materials normally used by the evaluators and similar to ratings of the resin composite normally used.

Adult↗

PubMed1997

Teaching of all-ceramic restorations in central European dental schools: a survey.

The teaching of all-ceramic restorations in Central European dental schools in the mid 1990s has been surveyed. Based on a 65% response, the findings indicate that the majority of undergraduate (pre-doctoral) students receive instruction in all-ceramic restorations with >75% gaining clinical experience in the use of such restorations prior to graduation. When clinical experience was not received, formal instruction, either in the regular curriculum or in elective studies was generally available. All the schools, with one exception, anticipated that the importance of teaching all-ceramic restorations would increase or at least stay the same. In general, the findings were similar to those reported in studies of the teaching of all-ceramic restorations in North America, Scandinavia, and the UK and Ireland, especially in relation to luting systems, contraindications and finishing instrumentation. However, clinical requirements for all-ceramic restorations in Central European dental schools were more common than in dental schools in North America, Scandinavia and the UK and Ireland.

Clinical Competence↗

PubMedDate not supplied

A practice-based assessment of the handling of a fast-setting polyvinyl siloxane impression material used with the dual-arch tray technique.

OBJECTIVE: The purpose of this study was to assess a new impression material used in conjunction with the dual-arch technique. METHOD AND MATERIALS: Ten members were selected at random from the Product Research and Evaluation by Practitioners (PREP) panel, a United Kingdom-based group of dental practitioners who are prepared to undertake research projects in their practices. Explanatory letters, a questionnaire, packs of the impression material, and dual-arch trays were distributed to the evaluators, together with instructions on the use of the materials. The practitioners were asked to use the materials and return the questionnaire after using the materials for a minimum of 10 impressions. RESULTS: Three evaluators had not previously used the dual-arch technique, six had used it in the past or occasionally, and one used the technique routinely. A total of 115 impressions were recorded with Quick Step. The overall rating for ease of removal of impressions from the mouth was 4.7 on a linear scale in which 5 represented easy to remove and 1 represented difficult to remove. Four of the evaluators rated the working time as excellent and the remaining six as good. Eight of the evaluators stated that the quality of fit of the single-unit restoration constructed with the combined-arch tray was the same as that obtained when a conventional tray technique was used. CONCLUSIONS: The impression material under test scored highly for application in circumstances where the fields above and below the preparation margin were dry or had limited moisture problems. Eighty percent of the evaluators considered the impression and dual-arch tray technique to be of benefit to their practice.

Dental Impression Materials↗

PubMedDate not supplied

A practice-based, randomized, controlled clinical trial of a new resin composite restorative: one-year results.

This study evaluated the performance of a low-shrinking resin composite compared with an amalgam for restoration of Class I and II cavities of moderate size in posterior teeth in a general practice setting. Fifty-two pairs of test and control restorations were placed in 49 patients. Clinical evaluations and assessments of replica models were carried out at baseline, six months and one year. Patients recorded their level of satisfaction with the restorations by means of visual analog scales. Apart from one control restoration that failed due to a fractured cusp, all of the restorations reviewed at six months and one year were intact with no unacceptable scores for any of the evaluation criteria. It was concluded that the resin composite evaluated, when used in conjunction with the recommended adhesive system, may be an appropriate alternative to amalgam in the restoration of posterior teeth over one year in clinical service.

Adolescent↗