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Acrylic partial dentures often do not receive the same attention to detail when being planned compared to cobalt–chromium prostheses. However, if a system of design is followed when planning acrylic dentures, retention, stability and support of the prostheses can be improved, increasing patient satisfaction. The aim of the third part of this series is to demonstrate how the design principles can be put into practice using a series of examples of the most common partially dentate situations encountered at the Birmingham Dental Hospital. CPD/Clinical Relevance: Knowledge of the principles of denture design for mucosal-borne partial dentures as applied to cmmon saddle situations. [ABSTRACT FROM AUTHOR]

Many dental students find the principles of partial denture design difficult to learn. It is also recognized that dentists in general practice within the UK do not always provide sufficient design specification on their laboratory prescription. It therefore seems that confusion about how to come up with a suitable denture design persists after graduation. The aim of the second part of this series relates to design principles of indirect retention, designing the major connector and how to put together all these elements when reviewing the overall design, and how to apply the denture concepts to a case study. This article also discusses recent advances in mucosal-borne partial dentures. CPD/Clinical Relevance: This article revises the principles of partial denture design specifically in relation to mucosal-borne partial dentures. [ABSTRACT FROM AUTHOR]

Many dental students find the principles of partial denture design difficult to learn. It is also recognized that dentists in general practice within the UK do not always provide sufficient design specification on their laboratory prescription. In that regard, it seems that confusion about how to come up with a suitable denture design persists after graduation. The aim of this series of articles is therefore to review the principles of denture design as applied to mucosal-borne dentures. Part 1 focuses on support, retention, reciprocation and bracing. CPD/Clinical Relevance: This article reviews the principles of design in relation to mucosal-borne partial dentures. [ABSTRACT FROM AUTHOR]

The success of complete dentures is highly dependent on the anatomy of the oral cavity. Several conditions can affect the final denture fit. Disorders of the soft tissues, such as denture hyperplasia, denture stomatitis and mucosal pathology may play a role. There are also difficulties related to the shape of the bone, including excessively large undercuts/bony exostoses, tori, enlarged tuberosities and flabby ridges and other factors, such as xerostomia to be considered. The aim of this article is to help diagnose these conditions and to suggest ways of overcoming the individual problems with which patients present before starting denture construction. CPD/Clinical Relevance: The diagnosis of several oral conditions and their appropriate management may help achieve an optimal outcome when constructing complete dentures. [ABSTRACT FROM AUTHOR]

The edentulous ridge classifications most commonly used have their limitations in treatment planning. They do not provide an indication of the complexities that may occur when constructing a new set of complete dentures. The new classification system suggested in this article helps with improved record-keeping, information exchange between colleagues, and communication between patient and clinician. CPD/Clinical Relevance: The new edentulous ridge classification system links the various edentulous ridge shapes to possible complications that could arise during denture construction. [ABSTRACT FROM AUTHOR]

PURPOSE: The aim of this study was to determine the mechanisms of failure of magnets used for denture retention. MATERIALS AND METHODS: Magnets were retrieved from dentures that had failed after 4 to 18 months of clinical use. The magnets were sectioned and the failure modes were evaluated using optical or scanning electron microscopy. RESULTS: The magnetic retention system investigated consists of a neodymium-iron-boron magnet sandwiched in a stainless steel keeper, capped with a titanium dome, and sealed with epoxy resin. The diffusion of moisture through the epoxy seal and the breakdown of the encapsulating material led to corrosion of the magnet. In both cases, a loss in retention occurred as the corrosion products weakened the overall magnetic attraction. CONCLUSION: The failure of magnets may occur by either breakdown of the epoxy seal or breakdown of the encapsulating material. Both problems need to be addressed to prolong the life span of these magnets. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate how clinical students reacted to the use of Podcasts for undergraduate teaching. The most popular way of listening to them was on a computer. Students scored highly the subject matter of the Podcasts and used them for learning around the subject, especially during examination time. Podcasts are a valuable vehicle for delivering learning materials to students: offering flexibility but in tune with students' love of downloading materials to use when they wish. [ABSTRACT FROM AUTHOR]

OBJECTIVES: The primary aim was: 'Does power-driven pocket/root instrumentation offer a clinical advantage over hand instrumentation'? Secondary aim was to update knowledge base of power-driven instrumentation post Tunkel et al. (2002). MATERIAL AND METHODS: A literature search of power-driven instruments (in vitro, in vivo and controlled clinical trials) was performed from April 2001 using similar criteria to Tunkel et al. (2002). Primary outcome was whether power-driven instruments offered an advantage over hand instrumentation; secondary outcomes were effect on root surface, effectiveness of new instrument designs, and role of biophysical effects such as cavitation. RESULTS: From a total of 41 studies, 14 studies involved comparison of power-driven devices with hand instrumentation for non-surgical therapy. These were subdivided into new designs of power instrumentation, full-mouth debridement and irrigation and patient acceptance. Use of power-driven instrumentation provides similar clinical outcomes compared with hand instrumentation. Difficulty of pooling studies continues to hinder the drawing of definitive conclusions. CONCLUSION: Newer designs of powered instruments have not shown any benefit when compared with other ultrasonic devices in non-surgical periodontal therapy. New in vitro research shows there is variation in the performance of different tip designs and generators, but its clinical relevance remains unknown. [ABSTRACT FROM AUTHOR]

AIM: During clinical usage, scaler tips may become worn and reduced in length. It is unknown what effect wear has on the magnitude of scaler tip vibrations when they are utilized under typical clinical loads. The aim of this investigation was to assess the effect of simulated wear on ultrasonic scaler tip displacement amplitude, using a scanning laser vibrometer. MATERIALS AND METHODS: A Cavitron SPS (Dentsply) ultrasonic generator and three scaler insert designs (FSI-100, FSI-1000 and FSI-SLI-10S) were selected for the investigation. Tip vibration displacement amplitude was assessed unloaded and then contacting against tooth surfaces with loads of 0.5 and 1.0 N. Tips were then ground down by 1 mm and then 2 mm and scans were repeated. RESULTS: For all tips, load and length were found to be significant variables (p<0.0001). The scaler tips showed a fall in displacement amplitude with a reduction in tip length. However, all scaler tips showed variability in the amount oscillation that occurred. This was most pronounced with FSI-SLI-10S. CONCLUSIONS: This investigation demonstrated that tip wear could affect the performance of dental ultrasonic scaler inserts by reducing their vibration displacement amplitude. Clinicians should be aware of this variability, which may be significant enough to affect clinical procedures. [ABSTRACT FROM AUTHOR]

OBJECTIVES: During ultrasonic scaling procedures, contact of the scaler tip with the tooth surface will produce frictional heating. The aim of this study was to assess this heat generation using an Agema 900 thermal imaging system. MATERIALS AND METHODS: Both the Cavitron sustained performance system (SPS) with TFI-3 tip and the Mini Piezon with P-tip were tested. Handpieces were fixed with their sides facing the thermal camera and thermal image sequences or 'movies' created. Measurements were performed with tips under loads of 25, 50 and 100 g, at water flow rates of 10, 20 and 40 ml/min and low, medium and high generator power settings. A measurement point was superimposed on the resulting thermal images at the tip/tooth contact site and the temperature variation with time recorded. RESULTS: All combinations of instrumentation produced an increase in temperature. An increase in temperature was generally observed with increasing load (for given power/water), power setting (for given load/water) and a decrease in water flow rate (for given load/power). CONCLUSION: Heat generation is minimised by using low/medium power settings and light contact. Care must be taken to ensure adequate water is present at the site of instrumentation to prevent patient discomfort due to excessive heating. [ABSTRACT FROM AUTHOR]

OBJECTIVES: The aim of this investigation was to assess the effect of loading on ultrasonic scaler tip displacement amplitude, using a scanning laser vibrometer. MATERIAL AND METHODS: Four generators were selected for this investigation including: Cavitron Select (Dentsply), Cavitron SPS (Dentsply), Piezon Master 400 (EMS) and Mini Piezon (EMS). The insert designs used with these generators included the TFI-10 and TFI-3 (with the Dentsply generators) and P-tip (with the EMS generators). The insert tips were contacted against tooth surfaces with loads of 0.25, 0.5 and 1.0 N. The scanning laser vibrometer was then used to scan the vibrating scalers at various generator power settings. RESULTS: The tips generally showed an increase in displacement amplitude with increasing power setting, although this increase was often nonlinear. Displacement amplitudes of like tips were generally found to be significantly different from each other at all loads. For individual inserts, loading caused a significant difference in tip response from the unloaded situation and also between loads. CONCLUSIONS: This investigation has demonstrated that there is a high variability associated with dental ultrasonic scaler inserts. Clinicians and researchers should be aware of this variability as it may affect both clinical procedures and future research. [ABSTRACT FROM AUTHOR]

OBJECTIVES: Scanning laser vibrometry is a noninvasive method of measuring the velocity, displacement amplitude and oscillation frequency of vibrating objects. The purpose of this study was to assess, using a scanning laser vibrometer (SLV), the performance of different designs of commercially available ultrasonic scaler generators by measuring the oscillatory characteristics of various scaler tips. METHODS: Four ultrasonic generators were tested (Cavitron SPS and Cavitron Select (Dentsply, York, PA, USA) and Piezon Master 400 and Mini Piezon (Electro-Medical Systems, Switzerland)) with various designs of scaler tip. The tips were positioned with their anterior surface perpendicular to the direction of the laser. A graduated scale, placed over the manufacturer's power dial, enabled incremental power setting selection. For each power setting, the laser beam from the SLV was scanned over the surface of the oscillating tip. RESULTS: The ranges of longitudinal displacement amplitudes (in micrometres) were as follows: Mini Piezon (P-tip): 12.90+/-1.44 to 44.03+/-7.80; Piezon Master 400 (P-tip): 16.02+/-2.66 to 35.85+/-5.29; Cavitron SPS (TFI-10 tip): 7.81+/-0.51 to 29.70+/-1.12; Cavitron Select (TFI-10 tip): 13.13+/-1.44 to 33.77+/-4.27; Cavitron SPS (TFI-3 tip): 5.50+/-0.46 to 31.35+/-3.62. CONCLUSIONS: This study shows that there are differences between commercially available generators and that tip movement varies between tips of the same style as well as between the generator and tip design. Users of ultrasonic scalers should be made aware of this inherent variability that may influence clinical procedures. [ABSTRACT FROM AUTHOR]