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The aim of this study was to examine the quality of master impressions and related materials for fabricating complete dentures in the UK. One hundred and fifty pre-piloted questionnaires were distributed to a number of dental laboratories in the UK with large catchment areas. Information requested related to the quality and choice of techniques for the master impression stage of fabricating complete dentures, as well as prescription of materials for occlusal registration, amongst others. All information was recorded anonymously. One hundred and forty-four completed questionnaires were returned. All items were provided on a private basis. Eighty-three per cent ( n = 119) of master impressions were made using a custom tray, the remainder were made using a plastic stock tray. The most commonly used impression material was zinc oxide-eugenol (42%, n = 60), followed by polyvinylsiloxane (39%, n = 56) and irreversible hydrocolloid (19%, n = 28). Master casts were poured after a minimum of 4 days. Eleven per cent of impressions examined ( n = 16) were judged to have errors. It was reported that 64% of master impressions ( n = 92) examined had been disinfected adequately. While this study revealed evidence of good clinical practice, particularly in relation to the selection of impression trays and quality of master impressions for complete dentures, there were some areas of concern, particularly in relation to the disinfection of the impressions examined. Dental practitioners should aim to provide their patients with high-quality prostheses by observing best clinical practice at all times. [ABSTRACT FROM AUTHOR]

Introduction Concerns regarding the preparedness of dental graduates often focus on the number of procedures undertaken before qualification.Aims To assess the validity of numerical requirements in determining whether a student has sufficient competency to graduate.Materials and methods In total, 50,821 observations of student activity while on the restorative clinic, for two integrated student cohorts (n = 139), were continuously recorded using the LiftUpp system from their third year to graduation. Analysis of data determined the most frequent type, location and difficulty of the direct restorations provided.Results Four groups of students, categorised by the total number of restorations they provided, were identified. Those with the most restorations (70+) had a statistically significantly greater experience in restoring different tooth surfaces, in different quadrants, on different patients than those with the least (40-49). However, increased numbers did not correlate with increasing difficulty, suggesting that students simply became more adept at easier procedures.Discussion Using a derived measure of 'consistency', it was observed that increased performance consistency was not correlated with greater overall experience. Furthermore, only 4% of students were 100% consistent in their performance in their final year.Conclusions These data suggest that a 'numerical requirements' approach cannot be used, in isolation, as a valid measure of the competency of an individual. Further work is needed to validate consistency as a holistic measurement to characterise the performance of graduates.

Dentine hypersensitivity is a frequently encountered patient complaint that can present with a number of associated factors including erosion and abrasion. the hydrodynamic mechanism responsible for dentine hypersensitivity is intimately related to the anatomical and physiological composition of teeth. Alterations to the integrity of the enamel and dentine through processes of trauma, decay and toothwear can increase dentine permeability. This gives rise to symptoms of sensitivity as dentinal fluid movement in response to thermal, chemical and mechanical cues stimulate the pulpal Aδ fibres. Restorative procedures can also rapidly change the architecture of the protective enamel and dentine layers leading to pulpal inflammation and increased thermal sensitivity of the tooth.
Patient-reported symptoms of dentine hypersensitivity can be attributed to a number of possible causes and a definitive diagnosis can therefore be difficult. A full history including social and medical factors such as occupation, diet and/or medication is likely to provide significant information to aid a diagnosis. Consideration of occlusal factors should not be overlooked as these may contribute to symptoms arising from a cracked tooth.
Management strategies are linked to the diagnosis - from topically applied desensitising pastes and resin bonding agents to direct restorations and possibly more advanced restorative procedures such as root canal treatment. Management should, however, be staged to enable more conservative strategies to prevail prior to considering irreversible dental interventions.

The aim of this study was to investigate the quality of communication and master impressions for the fabrication of cobalt chromium removable partial dentures (RPDs) in general dental practice in England, Ireland and Wales in 2009. Two hundred and ten questionnaires were distributed to 21 laboratories throughout England, Ireland and Wales. Information was collected regarding the quality of written communication and selection of master impression techniques for cobalt chromium partial dentures in general dental practice. One hundred and forty-four questionnaires were returned (response rate = 68%). Alginate was the most popular impression material being used in 58% of cases (n = 84), while plastic stock trays were the most popular impression tray, being used in 31% of cases (n = 44). Twenty-four per cent (n = 35) of impressions were not adequately disinfected. Opposing casts were provided in 81% of cases (n = 116). Written instructions were described as being 'clear' in 31% of cases (n = 44). In 54% of cases (n = 76), the technician was asked to design the RPD. Based on the findings of this study, written communication for cobalt chromium RPDs by general dental practitioners is inadequate. This finding is in breach of relevant contemporary legal and ethical guidance. There are also concerns in relation to the fabrication process for this form of prosthesis, particularly, in relation to consideration of occlusal schemes.

Objective: To investigate whether bleaching prior to placement of a composite veneer had an effect on the final shade of the restoration and whether this was affected by the thickness or shade of the veneer., Methods: Twenty bovine teeth were collected, sectioned and divided into two groups. One group was the non-bleached control, while the other was the bleached group. A colour reading was recorded using a spectrophotometer. The bleached group then underwent external bleaching with 38% hydrogen peroxide and a colour reading was recorded. Each of these two groups were further sub-divided into four subgroups, on which composite veneers were placed. These subgroups were: 0.5 m thick A1, 1 m thick A1, 0.5 mm thick A4 and 1 mm thick A4 composite veneers. Colour readings were recorded after veneer placement. Statistical significance was assessed using analysis of variance., Results: There was a difference between the colour produced for the same veneer properties, between the bleached and non-bleached groups. For a thin (0.5mm) A4 veneer bleaching produced a statistically significant difference in the amount of colour change (DeltaE) compared to veneering alone. For A1, non-bleached group there is a significant difference in the DeltaE produced by altering the thickness of the veneer., Conclusion: Within the limitations of this study, we can conclude that bleaching prior to placement of a thin A4 dark veneer produces a significant difference in colour change. If no bleaching is performed, altering the thickness of an A1 veneer produces a significant colour difference DeltaE. However, if bleaching is carried out there is no significant difference.

Objective: To assess the most efficacious method of treating stained teeth: bleaching alone, veneering alone or a combination of bleaching and veneering and whether the choice alters depending on the degree of staining., Methods: Extracted teeth were sectioned to give 117 samples. These samples were split into unstained, lightly and darkly stained groups based on CIE-Lab value L*. The lightly and darkly stained groups were stained using tea. Teeth from each group were then assigned to one of four subgroups (control (C), bleaching alone (B), veneering alone (V), or a combination of bleaching and veneering (BV), each containing 13 samples. Veneering was performed using 0.8-mm thick ceramic veneer of shade B1. CIE-Lab values were recorded using a spectrophotometer and the colour difference (Delta E) was calculated for each intervention. The final colour was compared to the value for obtained from a B1 (Vita) Shade tab. Statistical significance was assessed using analysis of variance., Results: In all three test groups, intervention resulted in a statistically significant colour change compared to the C group (p

Purpose: One of the barriers to restoring an edentulous space may be the supraeruption of an unopposed tooth to occupy some or all of the space needed for prosthetic replacement. The aim of this study was to determine the extent and type of supraeruption associated with unopposed posterior teeth and to investigate the relationship between these and oral and patient factors., Materials and Methods: Diagnostic casts of 100 patients with an unopposed posterior tooth and of 100 control patients were scanned and analyzed to record the extent of supraeruption, together with other clinical parameters. The type of eruption present was defined for each subject as Periodontal Growth, Active Eruption, or Relative Wear. Generalized Linear Models were developed to examine associations between the extent and type of supraeruption and patient or dental factors. The extent of supraeruption for an individual was modeled to show association between the degree of supraeruption and clinical parameters. Three models were produced to show associations between each type of supraeruption and clinical parameters., Results: The mean supraeruption for subjects was 1.68 mm (SD 0.79, range 0 to 3.99 mm) and for controls, 0.24 mm (SD 0.39, range 0 to 1.46 mm). The extent of supraeruption was statistically greater in maxillary unopposed teeth than in mandibular unopposed teeth. Supraeruption was found in 92% of subjects' unopposed teeth., Conclusions: A Generalized Linear Model could be produced to demonstrate that the clinical parameters associated with supraeruption are periodontal growth, attachment loss, and the lingual movement of the tooth distal to the extraction site. Three types of supraeruption, which may be present singly, or in combination, can be identified. Active eruption has an association with attachment loss. Periodontal growth has an inverse association with attachment loss, is more prevalent in younger patients, in the maxilla, in premolars, and in females. Relative wear has an association with increasing age and is more prevalent in unopposed mandibular teeth.

Purpose: Much anecdotal evidence is available on tooth positional changes following loss of an adjacent tooth, but only a few studies are available. In Part 1 of this series, supraeruption was assessed and Generalized Linear Models were made to determine the clinical parameters associated with the supraeruptive process. The models demonstrated that clinical parameters were not only associated with the extent of supraeruption, but also with the type of eruption present. This investigation of tooth positional changes adjacent to sites of posterior tooth loss attempts to provide increased understanding of the magnitude, direction, and associated features that may be helpful in decision making and treatment planning in the clinical setting., Materials and Methods: One hundred patients with an unopposed posterior tooth, with 100 age, sex, and bone level matched controls, were drawn from patients undergoing routine restorative care at Leeds Dental Institute. Study models were scanned, and the extent of eruption, type of eruption of the unopposed tooth, the overbite, overjet, buccal occlusion, and degree of crowding in the dentition, tipping, rotation, and buccal movement of the teeth associated with the edentulous site were recorded. Generalized Linear Models were developed to examine associations between each tooth movement and patient or dental factors., Results: A statistical significance in the degree of tipping of teeth both mesial and distal to the extraction site was detected between the subject and control groups. There was also a significant difference in rotation of the tooth mesial to the site. Four Generalized Linear Models were produced of the types of non-vertical movements found in teeth associated with sites of tooth loss., Conclusions: Teeth adjacent to the site of tooth loss may undergo non-vertical movements. Teeth mesial to the extraction site had a tendency to tip distally. The degree of tipping was increased in upper teeth and in subjects with a cusp-to-cusp buccal occlusion. Rotation of teeth mesial to the extraction site was more prevalent in the lower arch. Tipping of the tooth distal to the extraction site could be extreme and was found to be more prevalent in subjects with a reduced (Code 1) overbite and in the lower arch. Rotation of teeth distal to the extraction site was greater in the upper arch and was also associated with a reduced (Code 1) overbite. It also had an association with rotation of the tooth mesial to the extraction site. Models of non-vertical movement are likely to be of limited value due to overdispersion, indicating a high degree of variability within the model.

Objectives: To ascertain the requirements in restorative dentistry that undergraduate dental students have to fulfil in order to sit the finals examinations in dental schools in the UK and Ireland and to compare those requirements with the competencies stipulated by the GDC in The first five years., Methods: Fifteen anonymised questionnaires, of open and closed question design, were sent by post to academics in the university departments of restorative dentistry in each of the undergraduate dental schools in the UK and Ireland. The first section concerned numerical information regarding total numbers of procedures that were required to be completed in undergraduate restorative dentistry. The second section was designed to ascertain information as to how decisions are made with respect to an undergraduate's readiness to sit the finals examination in restorative dentistry (such as continual assessment and/or competency assessments)., Results: A total of 15 replies were received for analysis, a 100% response rate. Several institutions emphasised that they do not have 'requirements', but provide guidelines as to what should be achieved. Six institutions did not have set numerical requirements for direct placement restorations or bridges. The number of direct placement restorations required at the other nine institutions ranged from 50 to 160. Five institutions did not have numerical requirements for dentures; four institutions did not set numerical targets for crowns, veneers, inlays/onlays or endodontics. In institutions where numerical requirements were not used, forms of competency assessments were completed. The requirements across all institutions for periodontology, integrated treatment planning and completed cases were ill-defined., Conclusions: This study shows that there is a wide disparity amongst institutions in the UK and Ireland with regards to finals requirements in restorative dentistry. Ideally, such requirements should be similar between institutions and should be closely mapped to the GDC's required learning outcomes (The first five years) for the UK institutions.

Objective: To assess the effects of two polishing techniques on the surface roughness of a commercial and experimental dental ceramic for use in a chairside CAD-CAM system., Methods: A standard onlay was reproduced fifteen times in each of the two materials. Each stub was retained and examined using confocal microscopy in reflection mode. Five random samples of each were polished with Sof-Lex aluminium oxide discs, five polished with diamond impregnated polishing wheels and five left in the as-machined state. Surface roughness parameters were measured for each material group in each condition and statistical analyses carried out to determine the efficacy of the polishing techniques for each material., Results: The as-machined surfaces of both materials had a statistically similar surface finish. Polishing with Sof-Lex discs was effective at reducing surface roughness of both materials. Whilst the polishing wheels were effective in reducing surface roughness for the commercial material, there was no statistically significant difference in the surface roughness of the experimental material in the as-machined or wheel polished states., Significance: Although Sof-Lex discs were effective in reducing surface roughness of the two materials examined in this study, wheel polishing should not be used to reduce surface roughness of the experimental material. This will need to be taken into consideration in any future clinical studies of this material.

Objective: To test the null hypothesis that there is no color change when enamel porcelain thickness is changed and to evaluate the ability of a shade guide to prescribe chroma., Methods: Three shades (3M1, 3M2 and 3M3) were selected from a Vitapan 3D master shade guide. Five disk specimens were prepared for each shade, consisting of three layers (opacious dentin, dentin and enamel) at thicknesses of 0.6, 0.8 and 0.6mm, respectively. The color of each disk was measured using a spectrophotometer. Enamel porcelain was reduced in thickness to 0.3mm and porcelain disks were remeasured., Results: Reducing the enamel thickness of porcelain disk specimens significantly increased L) (p<0.05), b*, metric chroma and hue angle (p<0.001). For the three shades studied (3M1, 3M2 and 3M3) L* values were not significantly different (p>0.05) and chroma increased for 3M1 with the lowest chroma to 3M3 with the highest chroma, which is in line with the shade guide specifications. Although statistically significant (p<0.001) changes in hue angle between the three shades were small (less than 3 degrees overall). The difference in chroma between the three shades 3M1, 3M2 and 3M3 was greatest for the thin enamel layer than the thick enamel layer., Significance: A change in enamel thickness from 0.6 to 0.3mm resulted in a three-unit change in L* and metric chroma and a 4 degrees change in hue angle. A change in enamel porcelain thickness will have a greater effect on higher chromatic shades than those with lower chroma. The ability of the shade guide to prescribe chroma was demonstrated but this could be offset by an anomalous enamel thickness.

Objectives: The objective of this investigation was to determine the materials used in metallic post and core construction and investigate and the modes of failure that occurred resulting in post fracture., Methods: Eighty-five fractured metal posts were clinically retrieved over a 5-year period. The tooth with the fractured post, and relevant clinical details were recorded. Investigation of the fractured posts was undertaken to determine their constituent elements and modes of fracture using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX)., Results: The results showed that 77% of the posts were cast and 23% wrought. The modes of fracture were ductile (67%) or brittle (52%) although some posts exhibited both within the same specimen. In addition, evidence of fatigue was present in 20% of posts and porosity in 48%., Conclusions: A large variety of materials were used in the construction of post and cores although low-gold silver-palladium alloy most commonly encountered. Their failure was predominantly ductile in nature although a significant amount of brittle fracture was also noted. Porosity within castings also appeared to be a contributory factor in some cases and this was particularly evident in high-palladium castings. Evidence of fatigue was noted in a minority of posts.

One hundred and forty one male dental students and staff were screened for colour-defective vision. Ten colour-defective and 20 non colour-defective subjects then carried out a shade matching exercise using nine selected shades and another matched, shade tab (to test for consistency) from Vita shade guides. All shade matching took place under standard lighting conditions. Each subject also completed a short questionnaire relevant to shade matching. There were no significant differences found between colour-defective and non colour-defective subjects in shade matching abilities. Although both subject groups were similar in their shade matching abilities, individuals with colour defective vision perceived it to be a slightly more difficult exercise.

Aims: To compare the views of new vocational dental practitioners (VDPs) and their trainers regarding how undergraduate dental education has prepared them for their vocational training (VT) in England. This study also aims to identify areas of relative weakness in dental undergraduate education that could influence the future training needs of vocational trainees., Method: Structured postal questionnaires were completed by VDPs and trainers from five Deaneries in England. The usable response rate was 71% (n = 186 VDPs and 186 trainers)., Results: The vast majority of VDPs and trainers perceived the undergraduate training in history taking, diagnosis and treatment planning for general practice to have been covered 'well' or even 'very well'. Undergraduate training in routine restorative dentistry, oral pathology and paediatric dentistry was also perceived to have been covered well. However, a large proportion of VDPs and trainers reported that they felt that undergraduate training in orthodontics, molar endodontics, surgical endodontics and surgical extraction of teeth had not adequately prepared them for VT., Conclusions: Newly qualified dentists appear to lack certain competencies recommended by the General Dental Council in The First Five Years. This has implications for dental undergraduate education, but also highlights current training needs during VT.

Production of an appropriate occlusal curve for dentitions which have become deranged because of tooth loss, overeruption, tipping and drifting can present challenges for the dental technician. An earlier paper (J Oral Rehabil, 2005 32: 895-900.) demonstrates that the use of the Broadrick flag method for producing the occlusal curve is relatively accurate for most intact arches. This study demonstrates that when a posterior tooth has remained unopposed for 5 years or more positional changes, which cause deviation from the Broadrick curve, occur. The extent of the deviation may be extreme, potentially leading to difficulties in restoring a harmonious occlusal scheme. This study also demonstrates that the Broadrick curve may provide an accurate reproduction of the occlusal curve, even when the tooth forming the posterior determinant of the curve is tipped. A moderate degree of tipping of this tooth has little effect on the radius of the Broadrick curve.

Increasingly, clinicians are called upon to restore dentitions, which have become mutilated because of tooth loss, wear, trauma and disease. In many cases, restoration of the occlusal plane may be required. A simple tool, which provides the laboratory technician with an approximation of the patient's original occlusal curve may be useful. The purpose of this study is to determine the accuracy of the occlusal curve designed using the Broadrick flag. A total of 100 patients with intact dental arches were examined, and deviations from the Broadrick curve were measured on scanned study models using a software package. Simple descriptive statistics were used to investigate the data, and intra-examiner reliability was examined using a Bland Altman plot. The results demonstrated little deviation from the Broadrick curve in natural adult dentitions, mean deviation 0.1262 mm, 95% confidence interval -0.32 to 0.2844. Good intra-examiner reliability was achieved. It can be concluded that the Broadrick flag method may be of use in determining an appropriate occlusal curve for dentate individuals with deranged occlusal planes.

Objectives: Traditional teaching has advocated the placement of insulating materials under restorations to protect against 'thermal shock'. Often this involves placement of a thick zinc-oxide eugenol cement lining. The purpose of this in vitro study was to assess the heat transfer through four lining materials and dentine and to relate these findings to the temperature exposures that may be experienced in the oral environment., Methods: Two 'traditional' linings, zinc oxide eugenol cement (ZNOE) and calcium hydroxide paste (CAOH), and two more contemporary materials, a resin modified glass polyalkenoate (RMGP) and dentine bonding system (DBS) were studied in addition to dentine itself. Seven samples of each material were tested by utilising a Lees' Disc apparatus. Incorporation of thermocouples allowed heat transfer through the sample to be recorded. Thermal conductivity (J/m/s/ degrees C) was calculated for individual samples and a mean value obtained for each material. One way ANOVA and post hoc Tukey's tests were applied to the data obtained., Results: In ascending order of thermal conductivity, DBS

The purpose of this investigation was to determine whether non-setting calcium hydroxide [Ca (OH)2] cement placed in the root canal system of premolar teeth would affect the subsequent microleakage of a glass-ionomer restoration (GIC). Following selection, 62 human premolar teeth extracted for orthodontic reasons were accessed and root canals prepared according to a standardized procedure. The specimens were then allocated randomly into two major groups each of 30 teeth. Two other teeth were used as a positive and a negative control. The control group was restored with glass-ionomer cement following drying of the canal and placement of a cotton wool pledget. The test group had all canals dressed with non-setting Ca(OH)2 and then was subdivided, one set (n = 22) being restored following conditioning of the access cavity margins, the other (n = 8) having the margins cleaned with a hand excavator. Samples were assessed for microleakage using a two-point scoring system (leakage or no leakage) in conjunction with a clearing technique using AgNO3. Using Fisher's exact test, a statistically significant difference was found between the control and test groups (P < 0.05) but there was no significant difference between the excavated and conditioned cavities (P=0.55). It is concluded that contamination of access cavity margins with Ca(OH)2 during medication of a root canal interferes with the bond of GIC, resulting in increased microleakage in vitro.

Aim: To assess if a contrast medium improved diagnostic yield of endodontic radiographs., Methodology: Forty-five extracted mandibular premolar teeth were radiographed in bucco-lingual and mesio-distal planes. Access cavities were prepared, pulpal tissue extirpated and Ultravist contrast medium introduced under pressure. Radiographs were retaken and the teeth cleared following perfusion with India ink. Three examiners assessed all the films for: number of roots, number of root canals, curvature of root and/or root canal, presence of lateral canals, presence of a single foramen or apical delta and the presence or absence of canal obstructions. The examiners' interpretations were compared with the anatomy revealed by clearing., Results: Kappa scores were calculated for each of the examiners, for each set of radiographs, to assess the level of intra- and inter-examiner agreement. Only moderate agreement was found throughout (kappa = 0.40-0.61). For multiple root canals a false-positive result was significantly more likely with contrast (P < 0.05). The use of contrast did not significantly improve the sensitivity of diagnosis of lateral canals or a single apical foramen. Contrast significantly increased the risk of falsely perceiving lateral canals (P < 0.002). Overall there was no statistically significant difference in the overall assessment of the anatomy of the root canals using contrast or plain radiographs (P > 0.2)., Conclusions: Plain film radiographs confidently predict the presence of root or canal curvature but apical anatomy was assessed accurately in only 46% of cases. Plain radiographs were insensitive in assessing the number of root canals present, the presence of lateral canals and the occurrence of canal obstructions. The use of Ultravist contrast medium to improve diagnosis of root canal morphology of premolars is not supported.

How the dentition erupts, and what controls it, is fundamental to almost all aspects of clinical dentistry, yet the mechanisms behind this have not yet been fully elucidated. When the process continues into space that has been created through toothwear or tooth loss, problems in placing restorations can be encountered. This review examines the possible mechanisms of tooth eruption. Differences between processes in animals and humans are highlighted. The limitations of conclusions drawn from animal studies are then discussed with reference to human dental conditions. The differing forms of overeruption in humans are described and the treatment options for overerupted teeth, including prevention of the situation arising, are provided with a discussion of the quality of the evidence base behind these.

Aim: To determine any patient, technique or material factors that were significantly associated with post fracture in metallic post systems., Summary: Eighty-five fractured metal posts were retrieved over a 5-year period from a total of 84 patients who attended a dental hospital for treatment. A record was kept of the patient's dentition to identify the tooth with the fractured post, the number of teeth present, the excursive guidance scheme and the likely post design and material. Radiographs of 67 of these teeth were available. The presence or absence of a periapical lesion was noted as was the quality of the root filling. Maxillary lateral incisors, followed by maxillary centrals were associated with most of the fractured posts. The median survival to fracture was 36 months. The number of teeth in the dentition had a mode of 28. The most commonly fractured post design was a serrated and parallel design with an average diameter of 1.2 mm at the site of fracture. Apical lesions were found in 67% of the teeth with radiographs. Only 12% of teeth with a 'good' apical filling as opposed to 55% with a 'poor' apical filling had apical lesions., Key Learning Points: . Maxillary lateral incisors, followed by maxillary central incisors are at greatest risk of having a fractured metallic post. . Having a large number of teeth in the dentition or an adequate length of post was not protective against metallic post fracture. . Teeth with fractured post-retained crowns had a high incidence of apical lesions., (Copyright 2004 International Endodontic Journal)

Objectives: The aim of this in vitro study was to investigate whether dentin is exposed during tooth preparation for resin-bonded fixed partial dentures and, if so, to quantify the amount of dentin exposure., Method and Materials: Twenty extracted premolars were prepared in the following manner: The palatolingual and proximal axial surfaces were reduced by 0.50 mm. Mesial and distal grooves, 1.00 mm in depth, and mesial and distal occlusal rest seats, measuring 2.00 mm buccolingually x 1.50 mm mesiodistally x 1.00 mm deep, were prepared. The specimens were stained with a modified van Gieson's stain to identify dentin exposure, mounted on a jig to allow standardization, and photographed after 30-degree rotation to create a panoramic image of each tooth. The image was modified and analyzed to measure the percentage of the preparation area that exhibited dentin exposure., Results: Dentin exposure was noted in all specimens. The mean area of dentin exposure was 11.06 mm2 (16.15% of the preparation area). The minimum and maximum areas of dentin exposure were 4.07 mm2 (7.03%) and 19.73 mm2 (27.28%), respectively., Conclusion: Dentin is exposed during resin-bonded fixed partial denture preparation if current tooth preparation guidelines are followed, despite the commonly made recommendation that the preparation remain within enamel. The region of the grooves consistently exhibited exposed dentin; exposure at the cervical margin was variable.

Objective: The aim of this study was to determine whether a dentine bonding agent (DBA) had an effect in reducing fluid filtration under cemented provisional crowns., Methods: Crown preparations on 34 premolars, randomly allocated to two equal-sized test and control groups, were assessed for dentine permeability by a fluid filtration technique. In the test group, prepared crowns were acid-etched and then treated with a DBA (Prime & Bond NT). In the control group, no such DBA was applied. Provisional crowns were cemented on both groups of teeth using non-eugenol zinc oxide cement. Fluid filtration rates were measured repeatedly after crown preparation, at cementation, 1 h, 1 day, 1 week and 3 weeks following crown cementation for both groups. Filtration rates were also measured after acid-etching and dentine bonding for the test group., Results: There was insufficient evidence to suggest any statistically significant differences either between the two groups or, on average, across the five time points in each group in terms of the relative percentage of fluid filtration., Conclusion: The DBA used did not seal dentinal tubules any more than did the smear layer and provisional crowns luted with a non-eugenol ZnO cement.

Objectives: To determine the incidence and extent of overeruption in unopposed posterior teeth; to determine the incidence of occlusal interferences associated with unopposed posterior teeth; and to detect an association between the extent of overeruption and the presence of occlusal interference., Design: The study was a single centre clinical retrospective analysis. Setting The setting was in the Combined Care Clinic of Leeds Dental Institute. The patients were undergoing routine restorative care by final year undergraduate dental students during 2000., Subjects and Methods: All patients over18 years of age with one or more unopposed posterior tooth, were invited to participate. A sample group of 120 subjects were recruited. A clinical occlusal examination was carried out and the presence of initial retruded contact position (RCP) contacts and excursive interferences were recorded. Study models were made and digitally scanned., Outcome Measures: Measurements of overeruption from the curve of Spee were made from the images obtained, by a single observer. Reliability of the measurements was assessed by means of a Bland Altman Plot. The presence and site of RCP contacts and excursive interferences were recorded by a single observer. Reliability of the measurements was assessed by means of Kappa scores. The association between overeruption and the presence of occlusal interference was examined using Spearmans Correlation Coefficient., Results: A total of 120 subjects were recruited, with a total of 155 unopposed sites. Eighty-one of the sites belonged to male subjects, 74 to female subjects. The mean age of the group was 50.9 years, Standard deviation 13.9 Eighty-three per cent of sites displayed overeruption (95% CI 78-90), ranging from under 0.5 mm to 5.4 mm. The reliability of the observations was found to be good. A total of 51.6% (95% CI 44-60) of unopposed teeth were involved in RCP contacts or excursive interferences. Thirty-two sites were involved in more than one contact or interference. The intra-examiner agreement was found to be good, using Kappa. The findings of the Spearman's correlation, show that if an association exists between overeruption and occlusal interference, it is weak, and of no statistical significance., Conclusions: Eighty-three per cent of unopposed teeth are likely to overerupt, and the extent of the overeruption may be marked. The incidence and extent of overeruption is of clinical significance, not only in terms of treatment planning to prevent undesirable vertical movement, but also in the restoration of the edentulous space. The reliability of observations made in the study was found to be good, justifying the methodology. Fifty-one point six per cent of unopposed teeth are likely to be involved in RCP contacts or excursive interferences. The incidence is of clinical significance when planning the restoration of unopposed teeth, or the associated edentulous space. Only a weak statistical association was demonstrated between the degree of overeruption and the presence of occlusal interferences.

Objective: This pilot study was designed to measure tooth wear in a sample of 13 subjects who regularly use amphetamine-like drugs (Ecstasy, amphetamines) and compare the observed wear with a matched sample of nondrug users., Design: The two groups, both composed of 13 undergraduate students, were matched for age and sex. Other factors influencing tooth wear were controlled by matching the groups on their responses to a questionnaire asking about recognised common causes of tooth wear. The participants teeth were examined and the degree of wear scored according to a tooth wear index., Results: Severity of occlusal tooth wear of the lower first molar teeth was significantly greater in the drug user group than in the control group (P<0.05). No other statistically significant differences between the groups were found., Conclusion: Regular use of amphetamine-like drugs could be associated with increased posterior tooth wear.

Objective: The aim of this study was to compare the coronal microleakage of conventional and bonded amalgam coronal-radicular (Nayyar) restorations on endodontically treated molar teeth, because coronal seal is a major factor in the long-term success of endodontic treatment., Method and Materials: Forty extracted human molar teeth were root-filled and prepared for coronal-radicular amalgam restorations. Four groups of 10 teeth were restored with Tytin amalgam and Vitrebond, Superbond D Liner II, Panavia 21, or no adhesive agent. The teeth were placed in India ink for 1 week, and then demineralized and rendered transparent. The ink penetration was assessed with a coded scoring system., Results: The bonded amalgam groups produced significantly less leakage than did the nonbonded group. No statistically significant differences in leakage were detected among the bonded amalgam groups., Conclusion: To prevent the reinfection of the endodontically treated molar, it may be preferable to restore the tooth immediately after obturation by employing a bonded amalgam coronal-radicular technique.

Objectives: This in vitro study investigated the effect of selected luting media on the fracture resistance of a flame-sprayed all-ceramic crown., Methods: Three groups of 10 human upper premolar teeth were prepared for crowning using a standardised technique. Flame sprayed crowns were fabricated and cemented onto the preparations using zinc phosphate (ZPC), glass polyalkenoate (GPC) or composite luting cement (CLC). During crown seating, a pressure perfusion system simulated pulpal fluid outflow equivalent to 300mm of H2O. Compressive fracture resistance was determined for each group using a Universal Testing Machine with a crosshead speed of 1mm min(-1). A group of unrestored teeth acted as a control., Results: The fracture resistance of the groups ranked as follows: ZPC>CLC>>GPC=unrestored teeth. The difference between the fracture resistance of ZPC and CLC groups and the control group was statistically significant. The mode of fracture between the luted crowns and natural crowns was markedly different., Conclusions: When tested in compression, a new, flame-sprayed all-ceramic crown, when luted in place using ZPC, GPC or CLC, could produce strengths comparable to or greater than natural unrestored teeth. The luting agent used significantly affected the recorded fracture loads.

The aim of this in vivo pilot study was to record variations in temperature at various sites in a subject's mouth in response to a standardised thermal challenge and to determine a more realistic thermocycling regimen for future use. A volunteer who suffered from no dentinal hypersensitivity had modified study models prepared for constructing vacuum-formed PVC splints. Perforations 2 mm in diameter were placed for thermocouples facially and lingually in the midcoronal sites of the upper and lower central incisors, canines, second premolars, and second molars to measure temperatures at these sites. A standardised drinking regimen was followed of hot black coffee (72.5 degrees C) followed by cold orange juice (6.0 degrees C). Contralateral sites experienced similar temperature changes of short duration. A maximum of 68.0 degrees C and a minimum of 15.4 degrees C were recorded. Less extreme temperatures were experienced posteriorly, and little or no discernible changes were noted at the facial aspects of the upper second molars or lingually on the lower second molars. Most commonly used thermocycling regimens are clinically unrealistic, and temperatures vary widely throughout the mouth when hot or cold drinks are taken.

Objectives: The aims of this in vitro study were to (a) measure fluid flow through teeth restored with one of three dentine bonding systems and a resin composite restoration; (b) measure the distribution of a silver tracer through the same teeth, and make a comparison with fluid flow; and (c) investigate the effect of thermocycling on both measurement types., Methods: Coronal segments of 30 premolars, randomly allocated to three equal groups, were assessed by fluid filtration. Each group was restored with a resin composite restoration in conjunction with Fuji Bond LC (FBLC), Scotchbond Multi-Purpose Plus (SMP+) or Prime&Bond 2.1 (P&B2.1). Fluid filtration rates were measured in the intact crown and then after cavity preparation, conditioning, dentine bonding, restoration and at 2 and 24 h, 1 week and 1 month following restoration. Six specimens from each group were thermocycled at 1 week. After final filtration measurements the specimens were perfused with silver nitrate and cleared before scoring tracer penetration., Results: No significant differences (P > 0.05) in fluid filtration rates were found amongst the different bonding systems or at any restoration stage. Thermocycling was not associated with any significant (P > 0.05) increase in fluid filtration. Final fluid filtration and tracer distribution showed a weak and not statistically significant correlation (P > 0.05). The penetration of silver stain indicated a failure of the restorations to seal the cavity and demonstrated a possible pathway by which in vivo post-operative sensitivity could occur., Conclusions: Although not statistically significant, conditioning of the cavity increased the dentinal permeability but this effect was variable. Thermocycling had no statistically significant effect on microleakage.

Many microleakage studies, in their methodology, employ different tracers which may penetrate around restorative materials to varying extents due to their physical or chemical characteristics. The present series of in vitro studies were designed to compare the ability of freshly obtained microleakage tracers to enter cut dentinal tubules. Tracers selected were 5% eosin, 2% methylene blue, 50% silver nitrate and Indian ink all buffered, where necessary, to a range of pH 6.9-7.2. The solution of Indian ink was further investigated by particle size analysis to determine the range of particle sizes within the solution. Particles ranged from < 1 micron to 600 microns. Buffered and unbuffered solutions of the tracers were applied for 1 h to open cavities, devoid of a smear layer, prepared in 42 premolars. Specimens were sectioned longitudinally through the cavities either with or without water coolant. Penetration into dentinal tubules by the tracer resulted in an area of stained dentine and this area was subsequently measured using image analysis. The results demonstrated that there were few statistically significant differences between the areas of dentinal penetration associated with each tracer. Neither the tracer used, its pH nor sectioning technique had a predictably significant effect on dentinal penetration. Indian ink was observed to be capable of entering dentinal tubules.

This review paper discusses the recognised factors which predispose to cracked-tooth syndrome. In addition, common presenting symptoms and the various methods to aid clinical diagnosis of this problem are examined. The incidence of the condition is reported and the prognosis of the various forms of fracture, as suggested by clinical presentation, are outlined with reference to the available literature. Benefits and relative demerits of traditional and more modern treatment options are presented and recommendations made for future research.

This case illustrates an alternative management of a fractured non-vital incisor using adhesive techniques to avoid the disturbance of, and offer protection to, successful endodontic treatment. The rationale for the maintenance of sound tooth structure and the minimisation of coronal leakage, while adequately restoring aesthetics, is discussed.

The search to improve the properties of dental adhesives has lead to the development of light-cured glass ionomer cements. Using human teeth in vitro, the present study tested the shear/peel bond strengths of two light-cure materials ('Variglass VLC' and 'Fuji Lining LC') against a 'no-mix' composite orthodontic adhesive ('Right-On') and a chemically cured glass ionomer cement ('Ketac-Cem'). The light-cured materials were found to have an inferior bond strength compared with the two control adhesives. Based on the findings of this study, there is no evidence to support the use of the materials tested for the bonding of orthodontic brackets.

To find out whether adhesive techniques could have a role in bone fixation in selected cases an in vitro comparison between the current 'Champy' miniplate system and bonded stainless steel was undertaken using cyanoacrylate or dental composite cement. 33 bovine ribs were sectioned to simulate fracture separation, divided randomly into three groups, and immobilised by one of the three treatments. Distraction across the 'fracture' was produced using a universal testing apparatus, and forces at failure were recorded in Newtons (N). Image analysis enabled the contact area of the adhesive to be determined in mm2, so the bond strength in N/mm2 was derived. The Champy system failed at a significantly greater force (N) than the adhesives (p = 0.000). There was no significant difference in bond strength between either of the adhesive systems tested.

Objectives: This in vitro study aimed to examine the depth of preparation and incidence of dentine exposure resulting from the use of a 'freehand' technique to prepare maxillary central incisors for porcelain veneers., Methods: Twenty-two maxillary central incisors were selected. Prior to preparation an index of the labial surface of each tooth was recorded and the tooth secured in a jig to permit accurate relocation. Two operators each prepared 11 teeth aiming to reduce the labial thickness evenly by 0.5 mm. Low viscosity silicone impression material was then placed on the index and the teeth relocated into the jig. Upon removal, this material was sectioned in the cervical, middle and incisal thirds of the tooth and its thickness measured using a toolmaker's microscope. The teeth were acid etched and also stained with a dentine dye to identify any area of dentine exposed during preparation., Results: Significant differences (P < 0.001) in the depth of preparation at different sites, with least reduction in the mid-incisal region, were found. Greater reduction was found at the cervical and proximal margins with areas of dentine exposed at those sites in the majority of teeth., Conclusions: In view of the incidence and position of dentine exposure found in this study, the use of a dentine bonding system during the placement of porcelain veneers would appear essential when employing a 'freehand' preparation technique.

The aim of this study was to determine whether radiographs provide an accurate representation of the degree of root canal obturation following a cold lateral condensation technique. A total of 40 extracted single-rooted lower premolar teeth were prepared using either a standardized step-back technique or an ultrasonic device by one of two operators. The four groups each of 10 teeth were obturated using lateral condensation by a third operator. To assess apical leakage the obturated teeth were coated with nail varnish to within 2 mm of the apex and immersed in methylene blue for 48 h. The teeth were then radiographed in bucco-lingual and mesio-distal planes prior to subsequent sectioning in a bucco-lingual plane. Sections and radiographs were analysed using an image analysis apparatus to determine the proportion of root canal occupied by gutta-percha, void and/or sealer. Mean percentages of void calculated from the bucco-lingual radiographs, mesiodistal radiographs and tooth sections were 4.14%, 5.98% and 4.98%, respectively. Statistical analysis showed no significant differences between the radiographic views and the tooth sections (P > 0.05). Both planes of radiograph accurately represented the proportion of void when compared with the tooth section.

This study was undertaken to compare the quality of root canal obturation following preparation by endosonic or hand instrumentation. Forty single-canal, extracted lower premolar teeth were selected. One group of 20 teeth was prepared using a standard step-back technique, the other 20 teeth were prepared with an ultrasonic machine. The groups were subdivided, with two operators preparing 10 teeth of each group. The teeth were obturated by a third operator using cold laterally condensed gutta percha. The root apices were then immersed in methylene blue dye for 48 h and the teeth sectioned longitudinally. Image analysis recorded the amount of sealer and void within the obturated canal. The linear distance of dye penetration was measured to provide an indication of apical seal. Examination of the root canal shape resulting from the different preparation techniques used was also undertaken. No significant difference was noted in the percentage of sealer and void present in the root canals obturated after endosonic or hand instrumentation. There was a slightly greater although not significant increase in the degree of linear penetration of dye in canals prepared endosonically. The endosonic technique used in this study appeared to produce a canal preparation of slightly less continuous taper than that obtained with hand preparation.

The aim of this study was to examine whether it is more difficult to achieve complete obturation of the root canal in teeth from different age groups, using the measurement of voids within the obturated canal to determine the quality of endodontic therapy. One-hundred and fifty-two single-rooted premolar teeth extracted from patients of known age were collected. Following cleaning and storage the teeth were decoronated and radiographed. Forty selected teeth were allocated to one of four age-groups, (under 20, 20-35, 36-50, over 50 years) each consisting of 10 teeth. The working length was determined radiographically and preparation was carried out using the step-back technique. Each canal was obturated using cold lateral condensation with Tubliseal cement. The roots were then sectioned longitudinally and photographed. Sections and transparencies were subjected to image analysis to determine the total areas of root canal, sealer and voids respectively and statistical analysis of the differences between the various age groups was undertaken. There was a trend towards a reduction in the areas of sealer and sealer plus void with respect to increasing age group, although no significant differences existed. A significant relationship (P < 0.05) was found between the area of voids found in the youngest group when compared with all other groups, the greatest cumulative area of voids being found in the youngest teeth.

The aim of this study was to determine which dental cavity lining material exhibited least microleakage when used under amalgam. Extracted premolar teeth, prepared with Class II cavities, had one of three lining materials (cavity varnish, zinc oxide-eugenol or light-cured glass-ionomer) placed. Following restoration the teeth were immersed in eosin and sectioned. Sections were subjected to image analysis measuring the linear leakage and area of spread into coronal dentine. Percentages in relation to restoration length and the area of crown dentine were calculated. Light-cured glass-ionomer cement liner significantly (P < 0.05) reduced all aspects of the microleakage parameters studied.

Microleakage is commonly assessed using restored teeth, sectioned through the midline of the restoration. It is impossible to determine if this is representative of the leakage throughout the whole tooth. This pilot study examined the feasibility of calculating areas and volumes of leakage using serial sections of restored teeth which had been subjected to dye immersion and image analysis. Using the sections, perspex models of the teeth were constructed to present the pattern of the dye leakage into dentine. This appears to be a viable technique for the three-dimensional assessment of microleakage.

One hundred maxillary premolar teeth were randomly allocated to ten groups. Each group was restored with one of ten different restorative techniques. The teeth were stored in deionized water for 7d prior to longitudinal sectioning in a mesio-distal plane. Following sectioning, ten specimens from each group were chosen at random from the 20 available sections. The sectioned surfaces were polished using 600-grit SiC abrasive paper and etched for 10 s with 50% phosphoric acid to remove the smear layer produced by sectioning. Five tooth sections from the dentin bonding resin groups were allowed to dry at 20 degrees C for 24h. The glass ionomer-based groups were reimmersed in deionized water during this period. The remaining five sections from each group were replicated using an addition-cure vinyl polysiloxane impression material and an epoxy resin. A comparison was made of the sections and the replicas. All tooth specimens were sputter-coated with gold for 4 min and examined using a scanning electron microscope. Replicas were gold-coated for 3 min. Different tooth/restoration interfaces, associated with different materials, were observed. A marked difference between the replicas and tooth sections was observed for glass ionomer-based restorations but not for resin-based bonding systems. Representative samples of replicas and specimens are shown, and the significance of the observed differences is discussed.

The study aimed to determine the base/restoration combination which allowed the least microleakage in Class II cavities. One hundred premolar teeth were prepared with a standardized, minimal two-surface cavity and randomly ascribed to ten equal groups. The cavities were restored by use of one of ten different material/technique combinations. Restored teeth were sealed to within 1 mm of the restoration margins with nail varnish prior to the immersion of the crowns in 5% (buffered) eosin for 48 h. The teeth were then hemisected longitudinally, in a mesio-distal plane, through the midline of the restoration by means of a diamond disc with water coolant, and one half of each tooth was then photographed. The transparencies were examined by image analysis programmed to facilitate calculation of the percentage of the tooth/restoration interface and of the crown dentin exhibiting dye penetration. Light- and chemically-cured glass-ionomer-based restorations showed similar amounts of leakage when expressed as a percentage area of crown dentin. This was significantly (p less than 0.05) less than that shown by cavities both etched and bonded. Cavities restored without enamel etching or involving the use of a bonding system exhibited significantly (p less than 0.05) greatest leakage.

Fifty sound premolar teeth, extracted for orthodontic purposes and stored at room temperature in physiological saline since extraction, were prepared with a standardized minimal two-surface Class II cavity. The teeth were then ascribed randomly to five groups, each of ten teeth. Each of four groups was restored using a different dentine bonding system and the associated posterior composite resin according to the manufacturer's instructions. The fifth group was restored with Superbond C & B dentine bonding system and Occlusin composite. After immersion in de-ionized water for at least 7 days, the teeth were sealed with nail varnish to within 1 mm of the margin of the restoration. The teeth were then immersed in 5 per cent buffered Eosin for 48 h. Following mesiodistal sectioning the sections were photographed and subjected to image analysis to establish the length of dye penetration at the tooth/restoration interface and the amount of dye penetration into the crown dentine. Tripton/Occlusin and XR Bond/Herculite XR groups showed a significantly (P less than 0.05) smaller amount of leakage than Gluma/Lumifor or Scotchbond 2/P50 combinations when assessed as a percentage of the tooth/restoration interface exhibiting leakage. When the percentage of crown dentine showing dye penetration was considered, the Tripton/Occlusin group showed less leakage than the other material combinations. It is concluded that Tripton, when used with the recommended composite, will allow significantly less microleakage than Gluma/Lumifor, Scotchbond 2/P50 or Superbond C & B/Occlusin combinations and a similar amount to XR Bond/Herculite XR in vitro.

Premolar teeth with Class II amalgam restorations placed after the application of cavity varnish (Group A), a light cured glass ionomer base (Group B) and 40 per cent polyacrylic acid as a pretreatment agent, followed by unset cermet cement (Group C) were examined for marginal leakage using dye penetration and image analysis. Including amongst the parameters examined were linear leakage length and leakage area, which were found to have no consistent correlation. Group A and C did not generally show significant differences in the parameters examined, whereas Group B exhibited significantly less linear leakage (P less than 0.001), and significantly less leakage area when the stained area was expressed as a percentage of available dentine (P less than 0.001). While allowing some linear leakage, it was found that the light cured glass ionomer base appeared to prevent the dye from entering the dentine. It is concluded that an assessment based solely on the leakage length is inadequate and that some measurement of penetration into dentine should be included in order to fully assess the microleakage potential of a material or technique.

The shear/peel bond strength of a new material, a 'hybrid' of a composite resin and a glass ionomer cement, was compared in vitro with the bond strengths of a composite resin and of a glass ionomer cement. The new material had a significantly greater bond strength than the other materials tested and its properties were very similar to the composite resin. Unlike the glass ionomer cement, etching of the enamel before applying the adhesive is required. The clinical indications for using this new cement are discussed.

This study reports on the current status of the gold inlay in the undergraduate curriculum of Dental Schools in the UK and at the Prince Philip Dental Hospital, Hong Kong, to determine if the decline in the use of the cast gold inlay over the past 20 years is reflected in teaching at undergraduate level. A questionnaire, which was mailed to all the heads of departments of conservative dentistry in the UK, was designed to determine current teaching in respect of cast inlays. The results show that although the majority of UK dental schools continue to teach direct and indirect inlay techniques, a minority (4 and 5 respectively) no longer incorporate a practical exercise in this teaching. Reasons cited for the discontinuation of the technique are varied but the availability of simpler, more conservative techniques is emphasized. Examination of the treatment records at the Prince Philip Dental Hospital, Hong Kong, where the Class II inlay technique is taught both theoretically and practically, shows that only a small proportion of all posterior cast restorations fitted between May 1983 and April 1988 were inlays (4.6 per cent).