A. D. Walmsley

Profile and competences for the graduating European dentist – update 2009

This paper presents the profile and competences for the European Dentist as approved by the General Assembly of the Association for Dental Education in Europe at its annual meeting held in Helsinki in August 2009. A new taskforce was convened to update the previous document published in 2005. The updated document was then sent to all European Dental Schools, ministries of health, national dental associations and dental specialty associations or societies in Europe. The feedback received was used to improve the document. European dental schools are expected to adhere to the profile and the 17 major competences but the supporting competences may vary in detail between schools. The document will be reviewed once again in 5 years time. Feedback to the newly published document is welcomed and all dental educators are encouraged to draw upon the content of the paper to assist them in harmonising the curriculum throughout Europe with the aim of improving the quality of the dental curriculum.

The attitudes of undergraduate students and staff to the use of electronic learning

Background: Computer-aided learning (CAL) offers advantages over traditional methods of learning as it allows students to work in their own time and pace. The School of Dentistry at the University of Birmingham has created an electronic learning website, named the Ecourse. This is designed to be a web-based supplement to the dental undergraduate curriculum.Aim: The aim of this study was to determine the attitudes of third year dental students and members of staff about the Ecourse website.Method: A questionnaire was produced and piloted before being distributed to all 65 third year dental students to obtain their opinions about the Ecourse website. The views of Ecourse were sought from four members of staff by performing qualitative, semi-structured interviews.Results: Lecture handouts and textbooks were reported as the sources used most often, by 96% of students. Eighty-six per cent of students are accessing the Ecourse mainly at the School of Dentistry, but 53% are also accessing it at home. Students liked the multiple-choice questions, downloading extra notes and looking at pictures and animation to explain clinical procedures. The majority of the students (79%) want the Ecourse to be used as a supplement to the undergraduate programme and 7% wanted it to replace formal lectures. Staff recognised the benefits of the Ecourse but were concerned about plagiarism, the effect on lecture attendance and the lack of feedback from students on existing CAL material.Conclusion: Students consider the Ecourse as a positive method of supplementing traditional methods of learning in the dental undergraduate programme. However in contrast teaching staff expressed negative views on the use of e-learning.

Ultrasound in dentistry. Part 2—periodontology and endodontics

Ultrasound in the kHz frequency range is used widely in clinical dentistry. The most common uses are in the fields of periodontology and endodontics. The ultrasonic scaler works by the vibratory chipping action of the oscillating tip and is assisted by the presence of cavitational activity in the associated cooling water. When assessing clinical studies it is often difficult to interpret results from different workers due to the lack of standardization of the ultrasonic scaler. Operators should be aware of the oscillatory pattern of different instruments. Endosonics utilizes an ultrasonically oscillating endodontic file to clean and shape the root canal prior to obturation. The cleaning ability of such files is assisted by the occurrence of acoustic microstreaming forces. The endosonic file is prone to constraint when it contacts the canal wall which alters its oscillatory pattern. Clinical techniques should be modified to reduce this problem.

Magnets in medicine

Abstract As permanent magnet materials have developed, attempts have been made to take advantage of their improved properties in medical applications. Uses of magnets in medical applications range from their simple use for retention, through orthopaedics and fracture healing, to magnetomotive artificial hearts and pioneering brain surgery, where magnets are used to guide catheters. Magnets also find use in applications such as magnetic resonance imaging (MRI) scanners and drug delivery systems. This overview, based on an extensive review of the literature, chronicles the development of magnets in medicine and summarises areas where future research will be beneficial.

Investigations into the use of an ultrasonic chisel to cut bone. Part 1: forces applied by clinicians

OBJECTIVES To measure in vitro the direction and force of applied loads applied by clinicians when using both a conventional slow surgical handpiece (CH) and an ultrasonic chisel (USC) for cutting bone. STUDY DESIGN Five clinicians were asked to cut bovine bone using either an USC or a CH. The bone was placed on a force measurement system that could measure both longitudinal and downward loads. The rate of cut was calculated over a fixed time-period and the depth of cut measured using a penetratometer. RESULTS The magnitude of the longitudinal forces generated varied between 1.48 and 3.22 N (USC) and 0.04 and 4.56 N (CH). The CH had a pulling force directed towards the operator. Both instruments produced a similar range of downward forces although there was intra- and inter-operator variability. The rate of cut varied in a similar manner, however, the CH produced a significantly greater depth of cut (p < 0.05). CONCLUSIONS The force measurement system demonstrated differences in the way clinicians used the USC and CH instruments to cut bone. Of the two cutting methods investigated, the rotary bur is more efficient than the ultrasonic chisel. An ultrasonic chisel does cut bone in a different manner from a conventional bur and clinicians may require training before using it clinically.

Investigations into the use of an ultrasonic chisel to cut bone. Part 2: cutting ability

OBJECTIVES Ultrasound may offer a possible alternative to rotary instruments for removing bone. This study was undertaken to analyse in vitro the various factors that influence the cutting of bone by an ultrasonic chisel. STUDY DESIGN A block of bovine femur was moved in a longitudinal direction under a stationary ultrasonic chisel. The force and depth of the cut was recorded for cutting rates of 28-112 mm/min and with increasing rake angles of 0 to +20 degrees. The pressure exerted by the chisel was recorded for different cutting rates. RESULTS When the cutting rate increases there is a corresponding increase in the downward force which is followed by a decrease in the force at rates greater than 56 mm/min. The depth of the cut increases up to a rate of 56 mm/min after which it decreases. Both the longitudinal and downward forces do not change when the rake angle changes from 0 to +10 degrees. The downward force decreases when the rake angle increases from +10 to +20 degrees. CONCLUSIONS The bone is cut slowly with the ultrasonic chisel, but this would assist in precision. Where such an instrument is used for cutting bone the clinicians should be aware that both low forces and cutting rates are required, and the instrument should be held at a low rake angle.

Vibration characteristics of ultrasonic scalers assessed with scanning laser vibrometry

OBJECTIVES Scanning laser vibrometry is a non-invasive method of accurately measuring the vibratory characteristics of oscillating objects. The aim of this study was to observe, using a scanning laser vibrometer (SLV), the vibration patterns of dental ultrasonic scaler tips and to assess the effects of water flow rate and power setting on these patterns whilst operating the tips in an unloaded environment. METHODS A 30kHz ultrasonic scaler (TFI-10, Dentsply) was fixed in position and a laser beam from the SLV was focused onto the tip. The laser, guided by a virtual measurement grid, was scanned over the oscillating tip surface. Scans were taken with the laser beam perpendicular to the long axis of the front face of the tip. RESULTS Oscillation frequencies and the displacement amplitude at the unconstrained end of the tip were measured for various power/water settings. Vibration nodal positions were recorded for the various settings and were found to occur approximately 4mm from the free end of the tip. At low and medium power settings, tip displacement amplitude was reduced by increased water flow. At high power settings, combined with a high flow rate, the water leaves the body of the instrument as a jet. This left the tip relatively unconstrained, allowing it to oscillate at increased displacement amplitudes. CONCLUSIONS This study shows that the SLV is able to accurately characterise the movement of oscillating ultrasonic scaler tips. The tips are affected by power setting and water flow rates.

Implant supported overdentures — the Birmingham experience

OBJECTIVES The use of an implant retained overdenture with magnets offers a simple treatment approach to the problem of instability of the complete denture. Advantages with magnets include a simplified clinical technique and reduced lateral stresses on the abutments. This paper reports on a long-term study undertaken at Wordsley Hospital and Birmingham Dental teaching hospital in the West Midlands. METHODS Twenty-one patients received implant-retained overdentures with magnets over a 5-year period. The average age of the patients was 63 years (range 44-83 years). Seventy-eight Astra (Astra Tech AB, Mölndal, Sweden) implants were placed: 17 patients had four, two had three and two had two implants placed. RESULTS During the 5-year study, 11 implants were lost, one from infection, and the remaining 10 were lost because of a failure of osseointegration. This equates to an 86% success rate which increases to 97% when implants shorter than 1 cm are discounted. Over this period, the average number of dentures constructed per patient was 2.3. The main reason for denture replacement was a loss of function of the magnets. When the steel casing around the magnets was breached, then corrosion resulted. The life expectancy of the magnets over the 5-year period was 77 weeks (+/-50 weeks). One denture was replaced due to problems of instability. Patient satisfaction with the treatment remains high, and all patients can now wear dentures satisfactorily. CONCLUSIONS The use of a magnet retained overdenture offers a simple reconstructive approach to complete denture instability. Methods are currently being investigated to improve the clinical function and durability of the magnets. The success rate with the implants remains good after 5 years in function.

Ultrasonic Scaler Oscillations and Tooth-surface Defects

Damage to tooth root surfaces may occur during ultrasonic cleaning with both piezoelectric and magnetostrictive ultrasonic scalers. It is unclear which mechanism causes more damage or how their mechanism of action leads to such damage. Our null hypothesis is that tooth-surface defect dimensions, resulting from instrumentation with ultrasonic scalers, are independent of whether the scaler probe is magnetostrictive or piezoelectric. Piezoelectric and magnetostrictive ultrasonic scaler probes were placed into contact against polished dentin samples (100 g/200 g). Resulting tooth surfaces were evaluated with a laser metrology system. Ultrasonic instrumentation produced an indentation directly related to the bodily movement of the probe as it made an impact on the surface. Load, generator power, and probe cross-section significantly affected probe vibration and defect depth/volume. Defect dimensions were independent of generator type. Magnetostrictive probes oscillated with greater displacement amplitudes than piezoelectric probes, but produced similar defects. This may be due to the cross-sectional shape of the probes.

Inherent variability of the performance of the ultrasonic descaler

Abstract The displacement amplitudes of three different ultrasonic descaler probe tips were compared when driven by the same ultrasonic generator. Each descaling tip design gave different displacement amplitudes at the same instrument setting. This may be reflected in a difference in clinical effectiveness. A single design of probe tip also gave different displacement amplitudes when used with different generators supplied by the same manufacturer. Furthermore, during operation each particular design of probe tip exhibited differing patterns of oscillation superimposed on the expected longitudinal mode. Therefore, there is a need to measure the displacement amplitude of different probe tips to give a true indication of the acoustic power output of the instrument. Such calibration measurements must be made if users of ultrasonic descalers wish not only to rationalize and improve their clinical performance with the instrument, but also so that any investigative results can be compared in a meaningful manner with those obtained by other workers.