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Objectives This critical review is aimed to investigate the current status of qualitative research in dental implant research and to explore the quality of available information. Material and methods A systematic search was done on the journal databases to identify dental implant research articles that used qualitative methodology during 2006 and 2020. The resulting articles were appraised against the checklist offered by the Critical Appraisal Skills programme (CASP) tool. Also, the theories evolved from the research were reviewed to understand the value of this methodology in dental implant research. Results Twenty-five (25) articles out of the 8,421 original results were identified as using qualitative methodology. The researchers have sought to identify the views of patients about tooth loss, dental implants, and the information they receive from dental professionals, and views of the dentists about dental implant practice. The review found that there were few inconsistencies in the quality of such research especially the qualitative data analysis. Conclusions The quantity of qualitative research in dental implants remains low; however, the quality has improved in the past two decades. Despite these improvements, there is still a lack of research in understanding both patients' and dentists' views on dental implant procedures and management.

OBJECTIVES The aim was to evaluate the effectiveness of a pre-clinical training of ceramic crown preparation using the Virtual Educational System for Dentistry. MATERIAL AND METHODS Fifty-seven dental students were recruited to prepare a ceramic crown under the guidance of the Real-time Dental Training and Evaluation System (RDTES) in order to collect pre-learning data. They participated in the online virtual learning course independently on the Virtual Learning Network Platform (VLNP). One week later, the students were invited to complete their post-learning crown preparation with the RDTES. A questionnaire survey explored students' perceived benefits or drawbacks of the virtual educational system. Students were allocated into Group A (n = 15), B (n = 24) and C (n = 18) based on their pre-learning performance. Differences of assessment results amongst different groups were evaluated by ANOVA and Kruskal-Wallis tests. The pre- and post-learning assessment results in all groups were compared using paired t tests or Wilcoxon signed rank tests. RESULTS The error scores for four assessment items (instrument selection, preparation section, preparation reduction, preparation surface and profile) and total score of outcome assessment after the virtual learning were significantly different with those before the virtual learning (P

It is often the case that good teachers just "intuitively" know how to teach. Whilst that may be true, there is now a greater need to understand the various processes that underpin both the ways in which a curriculum is delivered, and the way in which the students engage with learning; curricula need to be designed to meet the changing needs of our new graduates, providing new, and robust learning opportunities, and be communicated effectively to both staff and students. The aim of this document is to draw together robust and contemporaneous methods of teaching, learning and assessment that help to overcome some of the more traditional barriers within dental undergraduate programmes. The methods have been chosen to map specifically to The Graduating European Dentist, and should be considered in parallel with the benchmarking process that educators and institutions employ locally.

Aim To investigate the effects of ultrasonic activation file type, lateral canal location and irrigant on the removal of a biofilm-mimicking hydrogel from a fabricated lateral canal. Additionally, the amount of cavitation and streaming was quantified for these parameters. Methodology An intracanal sonochemical dosimetry method was used to quantify the cavitation generated by an IrriSafe 25 mm length, size 25 file inside a root canal model filled with filtered degassed/saturated water or 3 different concentrations of NaOCl. Removal of a hydrogel, demonstrated previously to be an appropriate biofilm mimic, was recorded to measure the lateral canal cleaning rate from two different instruments (IrriSafe 25 mm length, size 25 and K 21 mm length, size 15) activated with a P5 Suprasson (Satelec) at power P8.5 in degassed/saturated water or NaOCl. Removal rates were compared for significant differences using non-parametric Kruskal–Wallis and/or Mann Whitney U tests. Streaming was measured using high-speed particle imaging velocimetry at 250 kfps, analysing both the oscillatory and steady flow inside the lateral canals. Results There was no significant difference in amount of cavitation between tap water and oversaturated water (P=0.538), although more cavitation was observed than in degassed water. The highest cavitation signal was generated with NaOCl solutions (1.0%, 4.5%, 9.0%) (P

Objectives: Maintaining oral health around titanium implants is essential. The formation of a biofilm on the titanium surface will influence the continuing success of the implant. These concerns have led to modified ultrasonic scaler instruments that look to reduce implant damage while maximising the cleaning effect. This study aimed to assess the effect of instrumentation, with traditional and modified ultrasonic scalers, on titanium implant surfaces and to correlate this with the oscillations of the instruments. Materials and methods: Two ultrasonic insert designs (metallic TFI-10 and a plastic-tipped implant insert) were selected. Each scaler probe was scanned using a scanning laser vibrometer, under loaded and unloaded conditions, to determine their oscillation characteristics. Loads were applied against a titanium implant (100g and 200 g) for 10 s. The resulting implant surfaces were then scanned using laser profilometry and scanning electron microscopy (SEM). Results: Insert probes oscillated with an elliptical motion with the maximum amplitude at the probe tip. Laser profilometry detected defects in the titanium surface only for the metallic scaler insert. Defect widths at 200 g high power were significantly larger than all other load/power conditions (P

Background: Online discussion boards may enhance critical analysis and reflection, and promote the acquisition of knowledge. Aims: To assess the effectiveness of online discussion board as a pedagogical tool in augmenting face-to-face teaching in dental education. Method: Data were collected from a discussion archive offered through the E-course website of the School of Dentistry, University of Birmingham, UK in 2008. A multi-component metric included; participation, social learning, cognitive processing, role of instructors, and quality of discussion. Messages were coded for 14 variables to evaluate these dimensions. Data were analyzed using content analysis methodology and a complete message was uses as the unit of analysis. Results: There were no significant difference in participation between students and instructors (P

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.

Background: The Objective Structured Clinical Examination (OSCE) is a method of assessing the clinical skills of undergraduates in medicine, dentistry and other health sciences and is employed increasingly in postgraduate education. Aim: To describe the application of the OSCE to the development of Lifelong Learning and Continuing Professional Development (CPD) for General Dental Practitioners (GDPs). Methods: A postgraduate course was designed as an OSCE for GDPs. The OSCE comprised 12 stations covering different aspects of general dentistry. After an introductory seminar outlining the aim of the course, the participants spent 7 min at each station. Each question or task required 10 answers and was designed to highlight areas of weakness or interest and to stimulate further study of the presenting topic. Solutions and answers were provided at each station for self-assessment along with a list of locally presented courses related to that subject. Participants were invited to leave contact details and to make suggestions for future postgraduate courses. The final session consisted of a group discussion and participants were invited to complete an evaluation form to express opinions on the course. Results: The evaluation demonstrated that most candidates found participation in the OSCE stimulated their interest in CPD. The OSCE also highlighted areas of weakness in knowledge of certain clinical procedures. Group discussion confirmed that practitioners found the hands-on component valuable and that they were likely to participate in further OSCEs to enhance their CPD. Suggestions received during the discussion were used to modify the course. Conclusions: The OSCE course fulfilled its aim of assisting practitioners to organise their CPD. The reflective nature of the course was helpful in evaluating clinical knowledge and the unique multidisciplinary style fulfilled its objective in promoting thoughts regarding future study.

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.

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.

Background: The ultrasonic dental scaler is a valuable tool in the prevention of periodontal disease; however, this equipment has a number of hazards with which it is associated. These include heating of the tooth during scaling, vibrational hazards causing cell disruption, possible platelet damage by cavitation, associated electromagnetic fields that can interrupt pacemakers, auditory damage to patient and clinician and the release of aerosols containing dangerous bacteria. Objective: To collate the research reported on the various hazards associated with the ultrasonic dental scaler and discuss possible future research areas. Data Sources: The scientific literature was searched using Web of Science, EMBASE and Medline, and the results of these were then hand-searched to eliminate nonrelevant papers. Conclusions: This review outlines some of the research conducted into these areas of associated hazard in order to assess their significance in the clinical situation, and discusses ideas for future research. Suggestions of recommendations are given, which have been previously investigated for their aid in reducing possible hazards, to ensure the safe working of ultrasonic scalers in the dental practice.

The Internet is an increasingly popular medium for delivering educational material. The aim of this study was to determine the attitudes of students and their clinical teachers to the use of the Internet within a dental school in the UK. Questionnaires were distributed to undergraduate dental students in the three clinical years and to all their clinical academic teachers. All students and staff have access to computers and Internet at the university. The majority (72%) of students have access to a computer and 53% also have access to the Internet at home. Of the academic staff, 91% have a computer and 68% have access to the Internet at home. The reasons for use of the Internet differed between staff and students. Whilst equal proportions of students used the Internet for dentistry (38%) and for pleasure (35%), a higher proportion of staff used the Internet more for dentistry (36%) than for pleasure (14%). Students highlighted cost and time as barriers to Internet use, whereas staff lacked confidence in their ability to use the Internet. Less than half (44%) of the students are confident in the accuracy of information from the Internet compared to almost two-thirds (64%) of staff. This study revealed differences in the attitudes of staff and students to the use of Internet as a resource for dentistry. Students are positive to the suggestion that lectures should be presented on the web. Most students (74%) did not see that this would influence attendance at lectures whilst 91% of staff stated that it would decrease lecture attendance. In conclusion, this study revealed differences in the attitudes of staff and students to the use of Internet as a resource for dentistry.

Aim To evaluate smear layer removal by different irrigating solutions under ultrasonic agitation. Methodology Twenty recently extracted mandibular incisors with a single root canal were divided into four equal groups. Three groups were instrumented using the modified double-flared technique, the fourth remained unprepared. Each group was irrigated with either distilled water, 1.0% sodium hypochlorite alone or associated with 15% EDTAC between each file size. The final group was not instrumented but irrigated with 1.0% sodium hypochlorite and 15% EDTAC. A size 15 file energised by ultrasound was used with small amplitude filing movements against the canal walls in all groups. The teeth were split longitudinally and the roots measured to provide three sections of the same size (cervical, middle and apical). Samples were examined under the scanning electron microscope and assessed for the amount of smear layer by three independent and calibrated examiners. The scoring system ranged from 1 (no smear layer) to 4 (all areas covered by smear layer). Due to the non-parametric nature of the data, Friedman’s test was used for statistical analysis. Results Canal walls were covered with smear layer in the group irrigated with 1% sodium hypochlorite alone and the group irrigated with distilled water. Canals irrigated with 1.0% sodium hypochlorite associated with 15% EDTAC had less smear layer throughout the canal (P

Background: Powered brushes were first introduced commercially in the 1960s. A recent systematic review suggested the superiority of certain modes of powered over manual toothbrushing for plaque and gingivitis reduction. That review did not allow for direct comparison between different modes of powered toothbrush. Objectives: To compare different modes of powered toothbrushing against each other for plaque reduction and the health of the gingivae. Other factors to be assessed were calculus and stain removal, cost, dependability and adverse effects. Search strategy: The following databases were searched: Cochrane Oral Health Group’s Trials Register (to 26 July 2010); Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 3); MEDLINE via OVID (1950 to 26 July 2010); EMBASE via OVID (1980 to 26 July 2010); CINAHL via EBSCO (1982 to 26 July 2010). There were no language restrictions. Selection criteria: Trials were considered for inclusion with the following criteria: random allocation of participants; no compromised manual dexterity; unsupervised powered toothbrushing for at least four weeks. The primary outcomes were the plaque and gingivitis scores after powered toothbrush use during trial period. Data collection and analysis: Data extraction was performed independently and in duplicate. The authors of trials were contacted to provide missing data where possible. The effect measure for each meta-analysis was the standardized mean difference (SMD) with 95% confidence intervals (CI) using the random-effects model. Potential sources of heterogeneity were assessed. Main results: The review included data from 15 trials with 1015 participants. Due to the dearth of trials assessing the same mode of action, no definitive conclusions can be stated regarding the superiority of one mode of powered toothbrush over any other. Only minor and transient side effects were reported. Cost, dependability were not reported. Authors’ conclusions: Further trials of good quality are required to establish if any mode of action has superiority over the other modes of action for powered toothbrushes. PLAIN LANGUAGE SUMMARY Different types of powered toothbrushes for plaque control and healthy gums Powered brushes were first introduced commercially in the 1960s. A previously published Cochrane systematic review suggested one type of powered brush was superior to manual toothbrushing for the removal of plaque and reduction of gum inflammation. That review did not allow direct comparison between the different types of powered toothbrushes. This review included data from 15 trials with 1015 participants. Due to the low numbers of trials using different types of powered brushes, no definitive conclusions can be drawn regarding the superiority of any one type of powered toothbrush over another. Only minor and transient side effects were reported. Cost and reliability of the brushes were not reported in the trials. Further trials of good quality are required to establish if any type of powered brush has superiority over the other types of action for powered toothbrushes.

The use of web browser technology allows the construction of computer-aided learning programs which will have a familiar interface to dentists. This paper reports on the evaluation of a web-based CAL program which covered the topic of tooth wear with an emphasis on the rôle of erosion in its aetiology. Evaluation of the software was made by 50 dentists contacted by an electronic mailing list. They completed a questionnaire which evaluated aspects of the functionality of the program educational objectives. The average age of the dentists was 39 years (range 24-70) and 82% were male. The average time of use was 1 h 10 min (range 15 min to 3 h). A significant change in their knowledge of tooth wear before and after using the program was recorded. Both the use of patient cases and leaflets scored highly with other aspects such as treatment planning and patient advice receiving high marks. All dentists commented that they had gained greater knowledge with particular reference to treatment and advice of tooth wear problems. 34 dentists (68%) found the web interface easy to use. Negative comments were mainly attributed to the quality of the pictures (4/50) which were corrected in the final release version. Respondents were asked to compare the program to other educational media on the same subject. 80% rated this CAL program as better than video, and 14% claimed it was as good as video. 84% rated it better than books, and 14% said it was as good as books. 98% preferred it to audio tapes and 86% preferred it to journals. The average amount that they would pay for a CAL package such as "tooth wear" would be 42 ECU. It is concluded that web browser software is a suitable medium for the use of a CAL program and this is reflected in its ease of use by dentists.

This study investigated the internal anatomy of 65 human mandibular canines with two well-defined roots. The teeth were decalcified and injected with gelatin coloured with india ink. Diaphanization was carried out using clear resin to allow permanent preservation. It was found that all mandibular canines with two roots had two root canals. Lateral canals were found in 68.9% of teeth and 19.7% had lateral canals at the bifurcation. The results of the external measurements (cusp tip to root apex) showed that the average buccal root length was 23.0 mm and the average lingual root length was 22.7 mm. The maximum and minimum buccal lengths were 26.7 mm and 17.9 mm respectively and the maximum and minimum lingual lengths were 27.2 mm and 17.1 mm respectively. The buccal root was the larger of the two in 47.7% of teeth and 43.1% had roots of equal size. The lingual root was larger than the buccal root in 9.2% of cases. Clinicians should be aware of the anatomical variation that exists for mandibular canines.

The aims of this investigation were to measure the thickness and taper of the different files (Heliosonic 15-40. Shaper 15-40 and Rispisonic 1-6) supplied with the MM1500 sonic instrument and relate this to their stiffness. The diameter of the files (n = 5 for each file type) was measured at 2 mm intervals using light microscopy and a calibrated graticule (mag x 120). A model system was developed for the stiffness testing. The file was held 3 mm from its tip and the load in g required to produce a 45 degrees deflection of the file was recorded. Measurements of file diameter showed that the width of the Heliosonic and Shaper increased in a linear manner and that the file taper was the same for increasing file sizes in accordance with ISO recommendations. The Rispisonic files however showed differing widths and degrees of taper which were not consistent with ISO standards. The stiffness testing results showed the Heliosonic files to be less flexible than the Rispisonic and Shaper files for all sizes (ANOVA, p < 0.001). The differences in stiffness of the Heliosonic, Shaper and Rispisonic files were due to the variation in cross sectional area of metal. In conclusion sonic endodontic files do not have the same taper and stiffness.

Endosonic files vary in their oscillation when operated in air with the greatest displacement at the unconstrained tip. It was the aim of this study to investigate how files of different lengths and sizes varied in their ability to cut dentine. Single rooted teeth were sectioned to produce 1 mm dentine discs. These were positioned on a plastic block connected to a load transducer. Endosonic K-files (#15 to 25) were used to cut the disc for 10 s using operator assisted movement. The files contacted the disc at the following points along their length; apical (3 mm from tip), middle (8 mm from tip) and coronal (13 mm from tip) under applied loads of 30 and 50 g. The depth of cut produced by each file was measured using light microscopy. The #15 and #25 were similar in their pattern of dentine removal. The #20 file produced a large variation in its cutting ability and was also susceptible to fracture. The tip of the files was prone to constraint at higher loading with the thicker part of the file producing more cutting. It was concluded that the pattern of dentine removal of endosonic files was affected by the amount of load applied. The displacement amplitudes of endosonic files in air would not appear to be a good indicator of file cutting ability.

This study examines the effect of a chlorhexidine irrigant during ultrasonic scaling and root planning and compares clinical results with those obtained using a water irrigant. The irrigant was delivered either through a conventional or a recently-introduced ultrasonic scaler, which allows the irrigant solution to be passed through the inside of the scaler tip. The study utilizes a split-mouth design and contrasts the effectiveness of both instruments in improving periodontal health, as measured by standard clinical indices. A preliminary investigation of patient tolerance to treatment performed throughout the clinical trial was also undertaken. Statistical analysis at the 3 and 6 month post-treatment stage revealed no significant differences between the 4 experimental groups in respect of probing attachment levels (P > 0.5), bleeding index (P > 0.1), or plaque index (P > 0.05). Clinical attachment gain assessed by probing ranged from 0.6 to 0.9 mm. Chlorhexidine increased patient tolerance in 77% of cases and the new model ultrasonic scaler was favored over the traditional model in 70% of cases. The magnitude of the tolerance differences was however not statistically significant. The possible potential of the new scaler and of chlorhexidine as an irrigant to reduce patient discomfort is worthy of further investigation than was possible in this study.

Acoustic microstreaming is known to be an important phenomenon associated with the use of clinically available endosonic systems. However, it has proved difficult to calibrate its pattern and effectiveness around the oscillating file. An in-vitro model system consisting of slow setting plaster was developed to demonstrate the activity of streaming around both ultrasonically and sonically activated files. For ultrasonic files, streaming occurred mainly in front of and behind the file, in contrast to the sonic file, where the plaster was disturbed evenly around it. With both types of file most activity occurred around the file tip, and became reduced towards the driver. Streaming patterns associated with the ultrasonic device were found to be dependent on the power setting of the instrument and whether the side of the file was constrained or lightly touched. The sonic device produced a large disturbance around the freely oscillating tip. Under load this streaming occurred along the whole length of the file, and was unaffected by constraint. This investigation demonstrated that streaming does occur with the instruments currently available, although it is dependent on their operating conditions. Clinical users of such equipment should be aware of the characteristic three-dimensional patterns of streaming that occur around these endosonic files, in order to maximize their efficiency.

The purpose of this study was to investigate the changes that occur in the dentogingival area during experimental gingivitis using a replication technique and scanning electron microscopy (SEM). The upper 1st premolars of 20 subjects were examined prior to plaque accumulation, after plaque had become clinically visible and after 3 weeks plaque accumulation. 3 distinct zones were examined: the tooth surface and its integuments, the gingival crevice and the oral gingiva. Surface features such as perichymata, pits, depressions and cracks were rapidly covered by plaque deposits. These had a raised globular surface with occasional embedded desquamated epithelial cells. Raised plaque colonies were frequently seen by the end of the study. Initially, the gingival crevice presented a layered undulating appearance. With plaque accumulation many desquamating epithelial cells were seen and variations occurred in the width of the crevice. These changes were mirrored in the oral gingiva. The junctional epithelium was initially smooth with occasional pores and emigrating leucocytes. As plaque accumulated, the presence of pores and leucocytes increased and considerable disruption by desquamating epithelial cells was noted. No subject proved resistant to the influence of plaque-induced changes.

A method of assessing the damaging effects of non-surgical instrumentation was developed. To test the technique, the effect of cavitational activity in the water supply of an ultrasonic sealer was investigated in an in vivo situation. Using a replication technique for the scanning electron microscope, it was shown that the water supply of the ultrasonic sealer caused superficial disruption of the surface of the gingiva, distant from the area of damage caused by mechanical contact. The results indicated that further investigations of this phenomenon using the technique were required.

Aim To correlate the vibrations of a retro tip under a range of loads and generator powers with its cutting ability. Methodology A scanning laser vibrometer was used to measure the maximum vibration displacement amplitude of a KiS 2D tip (Obtura Spartan, USA) under loads of 10–50 g (10 g increments). Loads were applied by contacting the tip against a polished root dentine surface (1200 grit) and were measured using a load cell (RDP Electronics, UK). A calibrated scale was placed over the power dial of the generator (Piezon Master 400; EMS, Switzerland) which enabled incremental power settings (1–5) to be selected between minimum and quarter power of the total generator output. Ten repeat scans were made for each load and generator power combination. The retro tip was then used to create cavities in polished dentine surfaces. The tip was operated using the same experimental conditions as described above (five power settings, 10–50 g loads). For each condition, the tip was contacted against surfaces for 5 s and used to make 10 repeat cavities. Cavities were scanned with a 3D laser profilometer (TaiCaan, UK), enabling the maximum width and length of the cavity to be measured. The same generator and handpiece were used throughout the experiment. Results Load significantly reduced tip vibration displacement amplitude at 30–50 g (P

Aim To evaluate the variability in power output between Piezon-Master 400 generators (EMS) with different Analytic handpieces (Analytic). The displacement amplitude of an unloaded KiS 2D (Obtura Spartan) root end preparation tip was measured using a Scanning Laser Vibrometer (SLV; Polytec) over a range of generator power settings. Methodology Four Piezon-Master 400 ultrasound generators were each used in conjunction with four analytic handpieces. A graduated scale was positioned over the power dial of each of the ultrasound generators to enable incremental power settings to be selected (six settings were used between the minimum and the 9 o'clock position). The handpiece with a KiS 2D tip was fixed in position so that the anterior surface of the tip was vertical and perpendicular to the scanner head of an SLV. Previous investigation showed that the maximum displacement amplitude of the oscillating tip occurred at the unconstrained end. The laser from the SLV was therefore scanned over this point to assess the maximum displacement amplitude. Scans were repeated 10 times for each power setting. The whole process was then repeated for all generator/handpiece combinations. Throughout the investigation, irrigation was used at a constant flow rate of 20 mL min−1. Results Linear trend lines fitted to all tip data showed that none of the generator/handpiece combinations produced a linear increase in tip displacement amplitude with increasing power setting. A univariate analysis of variance (general linear model) showed that generator, handpiece and power were all significant variables (P 0.66). No significant differences were found between handpieces 1 and 4 (P > 0.98) and handpieces 2 and 3 (P > 0.82). All other handpieces were significantly different from each other (P

Summary. Ultrasound has recently been introduced into endodontics to aid in the biomechanical preparation of the root canal. Although there are numerous investigations into the clinical efficacy of the endosonic system, there has been a poor understanding of the possible role of the biophysical aspects of ultrasound. Such areas where clarification is required are the possible roles of cavitation and acoustic microstreaming together with the ‘synergistic’ effect of the combined use of ultrasound and irrigant (usually sodium hypochlorite). Furthermore the oscillation of the file within the root canal may be prone to the load applied to it and this will greatly affect its efficiency. The present article aims to clarify these areas and to provide a guide to some of the biophysical terms used within the ultrasound discipline. Further investigations are required however to understand fully the action of the instrument, and it is hoped that this article will provide a basis for a scientific appraisal of endosonics.

Summary. When operated in air, the sonic endodontic instrument produced a movement at the driver head which resulted in a large elliptical oscillation of the file. This motion had similar properties to ultrasonically operated files in that there was a distinct variability in the magnitude of the vibratory motion between files of different design, length and thickness. When the sonic file was loaded, the elliptical motion was eliminated leaving a pure longitudinal file oscillation. This mode of vibration was particularly efficient as it was largely unaffected by loading, with the displacement amplitude being similar for different types of file used. The oscillatory pattern of the sonic file may offer a useful mode of mechanically assisted root canal preparaton.

Photomicrographs of the surfaces of recently extracted teeth stained with erythrosin dye were obtained. The stained surfaces were treated with an ultrasonic sealer using two different types of scaling tips driven by the same instrument operated at a medium power setting. Small areas of stained plaque removal occurred when the stationary scaling tip was operated without water cooling. Additional areas of removal were observed where a water coolant was present, which were larger than those produced by the non-water cooled tip. These additional areas were influenced by the type of scaling tip used, it's orientation to the tooth surface and it's displacement amplitude. Cavitational activity in the cooling water supply of the ultrasonic sealer is able lo remove dental plaque from tooth surfaces and may be a useful adjunct to the mechanical action of the instrument.