A preliminary evaluation into the performance of posterior resin bonded cast metal restorations (adhesive onlays).

Posterior resin bonded cast metal restorations (adhesive onlays) were used in a variety of clinical scenarios including: management of tooth wear and cracked tooth, as retainers for fixed bridge work, for correction of the occlusal plane and in providing cuspal coverage following endodontic treatment. The mean length in service for the examined onlays was 42 months, with a range of 9-75 months. Two restorations in two patients failed resulting in an overall success of 94%. Patient satisfaction was high at 95%. Such restorations seem to be a viable option for managing a number of clinical scenarios.

Surface properties of dental nanocomposites after finishing with rigid rotary instruments.

This study evaluated the surface characteristics of three nanoparticle resin composites (Z350, Heritage 7 Nanohybrid, and Ice) using profilometry and scanning electronic microscopy (SEM) after subjecting them to sequential finishing procedures using rigid rotary instruments. Fifteen 8 mm × 8 mm × 2 mm specimens were fabricated for each tested composite and subjected to one of the following finishing regimens: finishing with green stones followed by white stones, finishing with 45-µm diamond followed by 15-µm diamond, finishing with a 12-fluted carbide followed by a 20-fluted carbide. After finishing, the surfaces were subjected to profilometric testing. Eight parallel tracings were used to scan the finished surface of each specimen. For each recorded profile, the average roughness (Ra) and extreme value descriptor (Rmax) were recorded. On completion of the profilometric testing, two specimens from each group were randomly selected for qualitative assessment by SEM. Profilometric data was analyzed using a one-way analysis of variance and post hoc Scheffe tests. The results demonstrated that the three control groups of the tested nanocomposites behaved as a coherent group with respect to surface roughness. With the exception of the nanohybrid Heritage 7 finished with the carbide instruments, all composites showed an increase in surface roughness. The Z350 and Ice finished with the carbide finishing instruments showed no statistically significant increase in Ra, but both of these composites showed significantly rougher surfaces when finished with diamonds compared with controls. The nanohybrids Ice and Heritage 7 demonstrated significantly higher roughness in terms of Rmax when finished with stones. The SEM correlated well with roughness measurements. The conclusion may be drawn that diamonds and stones produce unacceptable surfaces in terms of roughness on the tested nanocomposites whereas finishing carbides produce acceptable surfaces.

Surface Properties of Dental Nanocomposites After Finishing With Rigid Rotary Instruments

This study evaluated the surface characteristics of three nanoparticle resin composites (Z350, Heritage 7 Nanohybrid, and Ice) using profilometry and scanning electronic microscopy (SEM) after subjecting them to sequential finishing procedures using rigid rotary instruments. Fifteen 8 mm·8mm·2mmspecimens were fabricated for each tested composite and subjected to one of the following finishing regimens: finishing with green stones followed by white stones, finishing with 45-lm diamond followed by 15-lm diamond, finishing with a 12-fluted carbide followed by a 20-fluted carbide. After finishing, the surfaces were subjected to profilometric testing. Eight parallel tracings were used to scan the finished surface of each specimen. For each recorded profile, the average roughness (Ra ) and extreme value descriptor (Rmax ) were recorded. On completion of the profilometric testing, two specimens from each group were randomly selected for qualitative assessment by SEM. Profilometric data was analyzed using aone-way analysis of variance and post hoc Scheffe tests. The results demonstrated that the three control groups of the tested nanocomposites behaved as a coherent group with respect to surface roughness. With the exception of the nanohybrid Heritage 7 finished with the carbide instruments, all composites showed an increase in surface roughness. The Z350 and Ice finished with the carbide finishing instruments showed no statistically significant increase in Ra , but both of these composites showed significantly rougher surfaces when finished with diamonds compared with controls. The nanohybrids Ice and Heritage 7 demonstrated significantly higher roughness in terms of Rmax when finished with stones. The SEM correlated well with roughness measurements. The conclusion may be drawn that diamonds and stones produce unacceptable surfaces in terms of roughness on the tested nanocomposites whereas finishing carbides produce acceptable surfaces.

The use of video-clips as a teaching aide

Introduction: Video-clips of tooth preparations recorded with a digital head-mounted camera replaced live demonstrations midway in a preclinical operative dentistry course. DVDs of the video-clips were made available to the students for home use. Aims: The aim of this study was to determine whether the use of these video-clips had any impact on students' practical examination results and to analyse students' opinions of this new technology and the perceived impact on their learning. Methods: A questionnaire was administered to all students (n = 26) who completed the course, asking their opinions on the video-clips. The results of student practical examinations before the introduction of the camera were compared with those after the video-clips were available and also to the examination outcomes of the previous year's students (ANOVA, P < 0.05). Results: Twenty-one students completed the questionnaire. Sixteen students (76%) preferred the video-clips to the live demonstrations, and 12 students (57%) made and reviewed the DVDs at home. They expressed a preference for the videos to be made available online or as podcasts. Twelve students (57%) felt that one-to-one supervision was more effective developing their competence in tooth preparations when compared to their viewing of the video-clips. There were no statistically significant differences between the practical examination results. Conclusion: In this group of students, video-clips were the preferred method of demonstration of tooth preparations in the preclinical environment. However, students perceived their learning to be facilitated more by one-to-one supervision. The students preferred to have the video-clips made available to them online instead of in the form of a DVD. The introduction of this educational aide did not make a difference in practical examination results.

The use of video-clips as a teaching aide.

INTRODUCTION: Video-clips of tooth preparations recorded with a digital head-mounted camera replaced live demonstrations midway in a preclinical operative dentistry course. DVDs of the video-clips were made available to the students for home use. AIMS: The aim of this study was to determine whether the use of these video-clips had any impact on students' practical examination results and to analyse students' opinions of this new technology and the perceived impact on their learning. METHODS: A questionnaire was administered to all students (n = 26) who completed the course, asking their opinions on the video-clips. The results of student practical examinations before the introduction of the camera were compared with those after the video-clips were available and also to the examination outcomes of the previous year's students (ANOVA, P < 0.05). RESULTS: Twenty-one students completed the questionnaire. Sixteen students (76%) preferred the video-clips to the live demonstrations, and 12 students (57%) made and reviewed the DVDs at home. They expressed a preference for the videos to be made available online or as podcasts. Twelve students (57%) felt that one-to-one supervision was more effective developing their competence in tooth preparations when compared to their viewing of the video-clips. There were no statistically significant differences between the practical examination results. CONCLUSION: In this group of students, video-clips were the preferred method of demonstration of tooth preparations in the preclinical environment. However, students perceived their learning to be facilitated more by one-to-one supervision. The students preferred to have the video-clips made available to them online instead of in the form of a DVD. The introduction of this educational aide did not make a difference in practical examination results.

Dual effects of ß3 integrin subunit expression on human pancreatic cancer models.

BACKGROUND: Pancreatic cancer, the fifth leading cause of adult cancer death in Western countries, lacks early detection, and displays significant dissemination ability. Accumulating evidence shows that integrin-mediated cell attachment to the extracellular matrix induces phenotypes and signaling pathways that regulate tumor cell growth and migration. METHODS: In view of these findings, we examined the role of ß(3) in pancreatic cancer by generating two stable ß(3)-expressing pancreatic human cell lines and characterizing their behavior in vitro and in vivo. RESULTS: Transduction of ß(3) selectively augmented the functional membrane α(v)ß(3) integrin levels, as evident from the enhanced adhesion and migration abilities related to active Rho GTPases. No effects on in vitro anchorage-dependent growth, but higher anoikis were detected in ß(3)-overexpressing cells. Moreover, tumors expressing ß(3) displayed reduced growth. Interestingly, treatment of mice with an α(v)-blocking antibody inhibited the growth of ß(3)-expressing tumors to a higher extent. CONCLUSIONS: Our results collectively support the hypothesis that α(v)ß(3) integrin has dual actions depending on the cell environment, and provide additional evidence on the role of integrins in pancreatic cancer, which should eventually aid in improving prediction of the effects of therapies addressed to modulate integrin activities in these tumors.

Effect of reduced exposure times on the microhardness of nanocomposites polymerized by QTH and second-generation LED curing lights.

This study investigated the effectiveness of polymerization of various curing regimes on five nanocomposite restorative materials­Z350, Grandio, Clearfil Majesty Esthetic, Ice and Tetric EvoCeram­by utilizing microhardness measurements. Five (n=5) disc-shaped specimens of each material were subjected to one of three curing regimes: curing with a halogen light for 20 seconds, curing with an LED light for 20 seconds and curing with an LED light for 10 seconds. Immediately following curing, hardness measurements were made with a Vickers indenter at five different locations on both the top and bottom surfaces of each disc. The mean for each surface was calculated. Data were analyzed using a one-way ANOVA and post-hoc Tukey HSD (α=0.05). The results demonstrated that among the Z350 composite samples, top and bottom microhardness values showed no statistical differences when cured with the halogen 20 second or LED 20 second regimes (p>0.05). Comparison of the top and bottom values of discs cured with the LED 10 second regime demonstrated significant differences (p<0.0001). Grandio samples cured with the halogen 20 second regime showed no statistical differences between top and bottom microhardness values (p>0.05); however, the bottom values of Grandio discs cured with the LED 20 second and 10 second regimes were significantly lower when compared with top surface values (p=0.001 and p<0.0001, respectively). Clearfil Majesty Esthetic, Ice and Tetric Evo Ceram samples cured with the halogen 20 second regime produced significantly lower bottom microhardness values, while both LED regimes produced top and bottom surfaces that were statistically comparable. The conclusion may be drawn that LED 10 second curing regimes were insufficient to cure Z350 and Grandio, while they were adequate for curing Clearfil Majesty Esthetic, Ice and Tetric EvoCeram.

Effect of Reduced Exposure Times on the Microhardness of Nanocomposites Polymerized by QTH and Second-generation LED Curing Lights

This study investigated the effectiveness of polymerization of various curing regimes on five nanocomposite restorative materials­Z350, Grandio, Clearfil Majesty Esthetic, Ice and Tetric EvoCeram­by utilizingmicrohardnessmeasurements. Five (n=5) disc-shaped specimens of each material were subjected to one of three curing regimes: curing with a halogen light for 20 seconds, curing with an LED light for 20 seconds and curing with an LED light for 10 seconds. Immediately following curing, hardness measurements were made with a Vickers indenter at five different locations on both the top and bottom surfaces of each disc. The mean for each surface was calculated. Data were analyzed using a one-way ANOVA and post-hoc Tukey HSD (α=0.05). The results demonstrated that among the Z350 composite samples, top and bottom microhardness values showed no statistical differences when cured with the halogen 20 second or LED 20 second regimes (p>0.05). Comparison of the top and bottom values of discs cured with the LED 10 second regime demonstrated significant differences (p<0.0001). Grandio samples cured with the halogen 20 second regime showed no statistical differences between top and bottom microhardness values (p>0.05); however, the bottom values of Grandio discs cured with the LED 20 second and 10 second regimes were significantly lowerwhen comparedwith top surface values (p=0.001 and p<0.0001, respectively). Clearfil Majesty Esthetic, Ice and Tetric EvoCeram samples cured with the halogen 20 second regime produced significantly lower bottom microhardness values, while both LED regimes produced top and bottom surfaces that were statistically comparable. The conclusion may be drawn that LED 10 second curing regimes were insufficient to cure Z350 and Grandio, while they were adequate for curing Clearfil Majesty Esthetic, Ice and Tetric EvoCeram.

Dual effects of ß3 integrin subunit expression on human pancreatic cancer models.

BACKGROUND: pancreatic cancer, the fifth leading cause of adult cancer death in Western countries, lacks early detection, and displays significant dissemination ability. Accumulating evidence shows that integrin-mediated cell attachment to the extracellular matrix induces phenotypes and signaling pathways that regulate tumor cell growth and migration. METHODS: in view of these findings, we examined the role of ß3 in pancreatic cancer by generating two stable ß3-expressing pancreatic human cell lines and characterizing their behavior in vitro and in vivo. RESULTS: transduction of ß3 selectively augmented the functional membrane αvß3 integrin levels, as evident from the enhanced adhesion and migration abilities related to active Rho GTPases. No effects on in vitro anchorage-dependent growth, but higher anoikis were detected in ß3-overexpressing cells. Moreover, tumors expressing ß3 displayed reduced growth. Interestingly, treatment of mice with an αv-blocking antibody inhibited the growth of ß3-expressing tumors to a higher extent. CONCLUSIONS: our results collectively support the hypothesis that αvß3 integrin has dual actions depending on the cell environment, and provide additional evidence on the role of integrins in pancreatic cancer, which should eventually aid in improving prediction of the effects of therapies addressed to modulate integrin activities in these tumors.

Disseminated nocardiosis: a rare infectious complication following non-heart-beating donor liver transplantation.

Nocardiosis is an infrequent disease that affects patients who display a cellular immunodeficiency, such as transplant recipients on immunosuppressive treatment, but uncommonly associated with high morbidity and mortality rates. Disseminated Nocardiosis affecting the central nervous system (CNS), abdomen, skin, and lungs has been described in bone marrow, lung, and kidney transplant recipients. However, to our knowledge, no cases involving all of these structures have been reported in liver transplant recipients. Herein, we have reported a case of CNS, pulmonary, and cutaneous nocardiosis in a liver transplant recipient who experienced hepatitis C virus-related cirrhosis and hepatocellular carcinoma and received the organ from a non-heart-beating donor. At posttransplantation month 7 the patient was admitted to the emergency department with poor general health status, fever, edema, and subcutaneous nodules in the legs. A computed tomography scan revealed multiple nodules disseminated through both lungs, abdomen, brain, and subcutaneous tissue. A needle biopsy was performed into one of the subcutaneous nodules. Cultures of the material tested positive for Nocardia farcinica. Thus, we started treatment with intravenous sulfamethoxazole-trimethoprim (SMZ-TMP), shifting after 1 month to oral therapy. Radiological examination performed after 2 weeks of treatment showed a 70% reduction in subcutaneous, pulmonary, and cerebral lesions. After 6 months of SMZ-TMP treatment, the patient remained free of the symptoms with involution of the subcutaneous nodules and significant radiological improvement. Among opportunistic infections appearing in liver transplant recipients, Nocardia species should have special consideration according to the success of early treatment and the bad prognosis in cases of delayed diagnosis.

The prevalence and severity of non-carious cervical lesions in a group of patients attending a university hospital in Trinidad.

Non-carious cervical lesions (NCCLs) are often encountered in clinical practice and their aetiology attributed to toothbrush abrasion, erosion and tooth flexure. This paper aims to determine the prevalence and severity of NCCLs in a sample of patients attending a university clinic in Trinidad and to investigate the relationship with medical and dental histories, oral hygiene practices, dietary habits and occlusion. Data were collected via a questionnaire and clinical examination. Odds ratios were used to determine the association of the presence of lesions and the factors examined. One hundred and fifty-six patients with a mean age of 40.6 years were examined of whom 62.2 per cent had one or more NCCLs. Forty five per cent of the lesions were sensitive to compressed air. Younger age groups had a significantly lower correlation with the presence of NCCLs than older age groups. Other significant factors included patients who reported heartburn, gastric reflux, headaches, bruxism, sensitive teeth and swimming or had a history of broken restorations in the last year. There was also significant correlation of NCCLs in patients who brushed more than once a day or used a medium or hard toothbrush. Patients with vegetarian diets and those who reported consuming citrus fruits, soft drinks, alcohol, yoghurt and vitamin C drinks were associated with the presence of lesions. Significant associations were also found in patients with group function, faceting, clicking joints or those who wore occlusal splints.

The prevalence and severity of non-carious cervical lesions in a group of patients attending a university hospital in Trinidad.

Non-carious cervical lesions (NCCLs) are often encountered in clinical practice and their aetiology attributed to toothbrush abrasion, erosion and tooth flexure. This paper aims to determine the prevalence and severity of NCCLs in a sample of patients attending a university clinic in Trinidad and to investigate the relationship with medical and dental histories, oral hygiene practices, dietary habits and occlusion. Data were collected via a questionnaire and clinical examination. Odds ratios were used to determine the association of the presence of lesions and the factors examined. One hundred and fifty-six patients with a mean age of 40.6 years were examined of whom 62.2% had one or more NCCLs. Forty five per cent of the lesions were sensitive to compressed air. Younger age groups had a significantly lower correlation with the presence of NCCLs than older age groups. Other significant factors included patients who reported heartburn, gastric reflux, headaches, bruxism, sensitive teeth and swimming or had a history of broken restorations in the last year. There was also significant correlation of NCCLs in patients who brushed more than once a day or used a medium or hard toothbrush. Patients with vegetarian diets and those who reported consuming citrus fruits, soft drinks, alcohol, yoghurt and vitamin C drinks were associated with the presence of lesions. Significant associations were also found in patients with group function, faceting, clicking joints or those who wore occlusal splints.

Tooth surface loss in adult subjects attending a university dental clinic in Trinidad.

OBJECTIVES: To determine the prevalence of tooth surface loss (TSL) in a sample of subjects attending a university dental clinic in Trinidad and to investigate the relationship to tooth brushing, medical history, parafunction and dietary habits. DESIGN: Tooth surface loss was measured clinically by the index used in the 1998 UK, Adult Dental Health Survey. SETTING: Trinidad, West Indies. PARTICIPANTS: Convenience sample of adult subjects attending The University of the West Indies Dental School Polyclinic, Mount Hope. METHODS: A questionnaire was administered and tooth surface loss measured clinically. MAIN OUTCOME MEASURES: mild, moderate and severe tooth surface loss. RESULTS: 155 subjects were examined (mean age 40.6 years) of whom 72% had some degree of TSL with the majority (52%), exhibiting mild, 16% with moderate and 4% with severe TSL. There were associations found between TSL and age (OR=3.14), reflux (OR=1.37), parafunction (OR=1.06), weekly consumption of citrus fruits (OR=1.31) and soft drinks (OR=1.78), daily consumption of alcohol (OR=1.40) and a vegetarian diet (OR=2.79). CONCLUSIONS: Tooth surface loss in this Trinidadian population group appears to be common. Data supports an association between TSL and age, reflux parafunction and certain dietary patterns.

An in vitro evaluation of shear bond strengths of glass ionomer/amalgam combinations

Purpose: The purpose of this study was to assess the shear bond strength of amalgam when bonded to dentine with various cements. Materials and Methods: Eighty human molars were divided into five groups and ground dentine surfaces treated, with one of five cements (Fuji I, Vitrebond, Rely X, Fuji II and Panavia F). Spherical amalgam (Tytin) was condensed onto the unset cement and shear bond strengths were measured after one week. Results: The mean shear bond strength of Panavia F (25.3 MPa) was significantly higher compared with Fuji I (16.8 MPa), Fuji II (10.3 MPa) and Vitrebond (5.1 MPa) however there was no significant difference with Rely X (19.0 MPa). Conclusion: The combination of a resin modified glass ionomer luting cement with a spherical alloy may enhance bonding of amalgam to dentine.