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Ultrasonic dental instrumentation
... We modified a dental ultrasonic descaler handpiece [38] ( Fig. 2), which uses a "stack" of piezoceramic rings bolted together with a back mass, front mass, and coupling horn. The piezoceramics are in the form of rings so that a bolt may pass through the center and hold them together. ...
... Another potential issue with the Langevin stack design is that the resonance frequency can drift as the internal elements (front/back masses, piezo stack) change dimension slightly with temperature. The dental descaling handpiece is designed to have water flow internally to keep the entire system cooled [38], and this was not possible with the device as used here. To ensure that the US source was operating at the frequency of maximum output, a separate small water tank (18 × 10 × 10 mm deep) was built with the Reson TC 4038 hydrophone mounted through a sidewall, and a fixture held the source directly above it. ...
This work describes a unique ultrasound exposure system designed to create very localized (~100μm) sound fields at operating frequencies that are currently being used for pre-clinical ultrasound neuromodulation. This system can expose small clusters of neuronal tissue, such as cell cultures or intact brain structures in target animal models, opening up opportunities to examine possible mechanisms of action. We modified a dental descaler, and drove it at a resonance frequency of 96kHz, well above its nominal operating point of 28kHz. A ceramic microtip from an ultrasonic wire bonder was attached to the end of the applicator, creating a 100μm point source. The device was calibrated with a polyvinylidene difluoride (PVDF) membrane hydrophone, in a novel, air-backed, configuration. Experimental results were confirmed by simulation using a monopole model. The results show a consistent exponentially decaying sound field from the tip, well suited to neural stimulation. The system was tested on an existing neurological model,
Drosophila melanogaster
, which has not previously been used for ultrasound neuromodulation experiments. The results show brain directed ultrasound stimulation induces or suppresses motor actions, demonstrated through synchronized tracking of fly limb movements. These results provide the basis for ongoing and future studies of ultrasound interaction with neuronal tissue, both at the level of single neurons and intact organisms.
... Moreover, the acoustic streaming induced by ultrasonic energy enhances the movement of irrigants, promoting deeper penetration into dentinal tubules and dislodging debris more effectively. The improved flow dynamics from acoustic streaming not only aids in the elimination of debris but also ensures thorough contact of the irrigant with all dentin surfaces [54]. For this reason, in the present study, an ultrasonic endodontic tip was used to remove bioceramic sealer residues, which form a strong chemical bond with dentin. ...
Background
Diabetes mellitus can alter the physical and mechanical properties of dentin, compromising bonding. Furthermore, residual sealer on dentin may inhibit the bond strength. The aim of this study was to evaluate and compare the effects of different cleaning protocols on the adhesive bond strength of composite to coronal dentin contaminated with a tricalcium silicate (TCS)based root canal sealer in diabetic and non-diabetic patients.
Methods
Diabetic (n = 50) and non-diabetic (n = 50) teeth were randomly divided into two groups. Coronal dentin surface specimens were obtained. The samples were contaminated with a TCS based sealer and then divided into five subgroups, four different cleaning procedures (dry cotton, wet cotton, ultrasonic-15, ultrasonic-30) and a control group (n = 10). The samples were restored with composite. A standard shear bond strength (SBS) test was performed. All failures were categorized as adhesive, cohesive or mixed. Data were analyzed using Independent Samples t-test and One-Way Analysis of Variance at a significance level of p < 0.05.
Results
SBS values were lower in diabetic dentin group than in non-diabetic dentin group. Dry cotton showed the lowest SBS value in both main groups. Ultrasonic-15 and ultrasonic-30 groups showed equal SBS values in the non-diabetic group (p = 0.001), while the highest SBS was seen in the ultrasonic-30 subgroup in the diabetic dentin group. The highest adhesive failure was observed in the diabetic dentin group, and the dominant failure type was mixed for both groups.
Conclusion
The use of dry cotton was an insufficient method for removing bioceramic root canal sealer residues from coronal dentin in both the diabetic and non-diabetic patients. 15 s of ultrasonic activation was effective for removing bioceramic root canal sealer remnants from the non-diabetic coronal dentin. However, for the coronal dentin in the diabetic group, 30-sec ultrasonic activation was the most effective method for removing bioceramic root canal sealer remnants.
Background
Aerosol and droplet production is inherent to dentistry. Potential for COVID-19 spread through aerosols and droplets characterizes dentistry as having a high risk of experiencing viral transmission, with necessity for aerosol and droplet mitigation.
Methods
Simulations of restorative treatment were completed on a dental manikin with a high-speed handpiece and high-volume evacuation suction. Variable experimental conditions with use of an extraoral vacuum suction at different distances from the simulated patient's mouth and different vacuum settings were tested to evaluate extraoral suction ability for droplet reduction.
Results
Using the extraoral suction unit during dental procedure simulations reduced droplet spatter at the dentist’s eye level, as well as the level of the simulated patient's mouth. When the extraoral suction unit was used at level 10 and 4 inches from the simulated patient's mouth, less spatter was detected.
Conclusions
Extraoral suction units are an effective method of reducing droplet spatter during operative dental procedures and can be useful in helping reduce risk of experiencing COVID-19 spread during dental procedures.
Practical Implications
During the pandemic, dentistry and its aerosol-generating procedures were placed on hold. The process to getting back to patient care is multifactorial, including personal protective equipment, patient screening, and mitigating aerosol spread.
The use of cavitation for improving biofilm cleaning is of great interest. There is no system at present that removes the biofilm from medical implants effectively and specifically from dental implants. Cavitation generated by a vibrating dental ultrasonic scaler tip can clean biomaterials such as dental implants. However, the cleaning process must be significantly accelerated for clinical applications. In this study we investigated whether the cavitation could be increased, by operating the scaler in carbonated water with different CO2 concentrations. The cavitation around an ultrasonic scaler tip was recorded with high speed imaging. Image analysis was used to calculate the area of cavitation. Bacterial biofilm was grown on surfaces and its removal was imaged with a high speed camera using the ultrasonic scaler in still and carbonated water. Cavitation increases significantly with increasing carbonation. Cavitation also started earlier around the tips when they were in carbonated water compared to non-carbonated water. Significantly more biofilm was removed when the scaler was operated in carbonated water. Our results suggest that using carbonated water could significantly increase and accelerate cavitation around ultrasonic scalers in a clinical situation and thus improve biofilm removal from dental implants and other biomaterials.
Purpose:
Piezoelectric bone surgery was introduced into clinical practice almost 20 years ago as an alternative method for cutting bone in dental surgical procedures, in an attempt to reduce the disadvantages of using conventional rotary instruments. The aim of this Consensus Conference was to evaluate the current evidence concerning the use of piezoelectric surgery in oral surgery and implantology.
Materials and methods:
Three working groups conducted three meta-analyses with trial sequential analysis, focusing on the use of piezoelectric surgery in impacted mandibular third molar extraction, lateral sinus floor elevation and implant site preparation. The method of preparation of the systematic reviews, based on comprehensive search strategies and following preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, was discussed and standardised.
Results:
Moderate/low evidence suggests that piezoelectric surgery is significantly associated with a more favourable postoperative course (less pain, less trismus) after impacted mandibular third molar extraction than conventional rotary instruments. Moderate evidence suggests that implants inserted with piezoelectric surgery showed improved secondary stability during the early phases of healing compared with those inserted using a drilling technique. Strong/moderate evidence suggests that piezoelectric surgery prolongs the duration of surgery in impacted mandibular third molar extraction, sinus floor elevation and implant site preparation, but it is unclear whether the slight differences in duration of surgery, even if statistically significant, represent a real clinical advantage for either operator or patient. Weak evidence or insufficient data are present to draw definitive conclusions on the other investigated outcomes.
Conclusions:
Further well-designed trials are needed to fully evaluate the effects of piezoelectric surgery, especially in implant site preparation and sinus floor elevation.
The aim of this study was to evaluate whether piezoelectric bone surgery (PBS) for impacted lower third molar extraction reduces the surgical time and risk of intra- and postoperative complications in comparison with conventional rotary instruments. This meta-analysis followed the PRISMA guidelines and was registered in the PROSPERO database. The PubMed, Embase, Scopus, and OpenGrey databases were screened for articles published from January 1, 1990 to December 31, 2018. Selection criteria included randomized controlled trials (RCTs) comparing PBS with conventional rotary instruments for impacted lower third molar extraction and reporting any of the clinical outcomes (intra- and postoperative complications and duration of surgery) for both groups. A risk of bias assessment was performed using the Cochrane Collaboration tool. A meta-analysis was performed, and the power of the meta-analytic findings was assessed by trial sequential analysis (TSA). Strong evidence suggests that PBS prolongs the duration of surgery and low evidence suggests that PBS reduces postoperative morbidity (pain and trismus) in comparison with rotary instruments. Data were insufficient to determine whether PBS reduces neurological complications and postoperative swelling in comparison with burs.
Objective:
Irrigant activation has been claimed to be beneficial in in vitro and clinical studies. This systematic review aims to investigate the clinical efficiency of mechanically activated irrigants and conventional irrigation.
Methods:
A literature search (PROSPERO registration number: CRD42018112595) was undertaken in PubMed, Cochrane and hand search. The inclusion criteria were clinical trials, in vivo/ex vivo on adult permanent teeth involving an active irrigation device and a control group of conventional irrigation. The exclusion criteria were studies done in vitro, animals and foreign language. Adult patients requiring endodontic treatment of permanent dentition and irrigant activation during the treatment were chosen as the participants and intervention respectively.
Results:
After removal of duplicates, 89 articles were obtained, and 72 were excluded as they did not meet the selection criteria. 6 devices (EndoVac, EndoActivator, Ultrasonic, MDA (manual dynamic agitation), CUI (Continuous Ultrasonic Irrigation) and PUI (Passive Ultrasonic Irrigation)) and 6 variables of interest (Post-operative pain, periapical healing, antibacterial efficacy, canal and/or isthmus cleanliness, debridement efficacy and delivery up to working length) were evaluated in the 17 included articles. The risk of bias and quality of the selected articles were moderate. Results showed that mechanical active irrigation reduces post-operative pain. It improved debridement, canal/isthmus cleanliness. It also improved delivery of irrigant up to working length. Bacterial count was more with active irrigation, though not significant. There is no effect on long-term periapical healing.
Conclusion:
It may be concluded that mechanical active irrigation devices are beneficial in reducing post-operative pain and improving canal and isthmus cleanliness during Endodontics.
In‐vitro studies suggest that electromagnetic interference can occur under specific conditions involving proximity between electronic dental equipment and pacemakers. At present, in‐vivo investigations to verify the effect of using electronic dental equipment in clinical conditions on patients with pacemakers are scarce. This study aimed to evaluate, in vivo, the effect of three commonly used electronic dental instruments – ultrasonic dental scaler, electric pulp tester, and electronic apex locator – on patients with different pacemaker brands and configurations. Sixty‐six consecutive non‐pacemaker‐dependent patients were enrolled during regular electrophysiology follow‐up visits. Electronic dental tools were operated while the pacemaker was interrogated, and the intracardiac electrogram and electrocardiogram were recorded. No interferences were detected in the intracardiac electrogram of any patient during the tests with dental equipment. No abnormalities in pacemaker pacing and sensing function were observed, and no differences were found with respect to the variables, pacemaker brands, pacemaker configuration, or mode of application of the dental equipment. Electromagnetic interferences affecting the surface electrocardiogram, but not the intracardiac electrogram, were found in 25 (37.9%) patients, especially while using the ultrasonic dental scaler; the intrinsic function of the pacemakers was not affected. Under real clinical conditions, none of the electronic dental instruments tested interfered with pacemaker function.
Purpose:
To evaluate the negative auditory and non-auditory effects developed immediately after using ultrasonic scalers and their potential role in the development of permanent hearing loss.
Materials and methods:
The auditory functions of 60 dental clinicians were evaluated with the pure tone audiometry test (PTA), tympanogram and the otoacoustic emission test (OAE) before and immediately after using ultrasonic scalers. The paired t-test was used to evaluate the difference in the pre- and post-exposure recordings for all three tests.
Results:
There was a significant increase in the PTA and tympanogram test results, along with reduced OAE values immediately after using ultrasonic scalers. Hearing ability dropped by 63% to 66% immediately after using ultrasonic scalers. The maximum hearing disability was noted for low-frequency thresholds. The reduction was greater in the left than in the right ear.
Conclusions:
Noise-emitting devices such as ultrasonic scalers produce significant immediate auditory and non-auditory changes. It is important that dentists recognise the initial signs of hearing damage and adopt appropriate measures while working to prevent the development of permanent hearing impairment in future.
Cavitation occurs around dental ultrasonic scalers, which are used clinically for removing dental biofilm and calculus. However it is not known if this contributes to the cleaning process. Characterisation of the cavitation around ultrasonic scalers will assist in assessing its contribution and in developing new clinical devices for removing biofilm with cavitation. The aim is to use high speed camera imaging to quantify cavitation patterns around an ultrasonic scaler. A Satelec ultrasonic scaler operating at 29 kHz with three different shaped tips has been studied at medium and high operating power using high speed imaging at 15,000, 90,000 and 250,000 frames per second. The tip displacement has been recorded using scanning laser vibrometry. Cavitation occurs at the free end of the tip and increases with power while the area and width of the cavitation cloud varies for different shaped tips. The cavitation starts at the antinodes, with little or no cavitation at the node. High speed image sequences combined with scanning laser vibrometry show individual microbubbles imploding and bubble clouds lifting and moving away from the ultrasonic scaler tip, with larger tip displacement causing more cavitation.
New measurements indicate that the public are being exposed, without their knowledge, to airborne ultrasound. Existing guidelines are insufficient for such exposures; the vast majority refers to occupational exposure only (where workers are aware of the exposure, can be monitored and can wear protection). Existing guidelines are based on an insufficient evidence base, most of which was collected over 40 years ago by researchers who themselves considered it insufficient to finalize guidelines, but which produced preliminary guidelines. This warning of inadequacy was lost as nations and organizations issued 'new' guidelines based on these early guidelines, and through such repetition generated a false impression of consensus. The evidence base is so slim that few reports have progressed far along the sequence from anecdote to case study, to formal scientific controlled trials and epidemiological studies. Early studies reported hearing threshold shifts, nausea, headache, fatigue, migraine and tinnitus, but there is insufficient research on human subjects, and insufficient measurement of fields, to assess what health risk current occupational and public exposures might produce. Furthermore, the assumptions underpinning audiology and physical measurements at high frequencies must be questioned: simple extrapolation of approaches used at lower frequencies does not address current unknowns. Recommendations are provided. © 2016 The Author(s) Published by the Royal Society. All rights reserved.
Ultrasonic instruments have been used in dentistry since the 1950's. Initially they were used to cut teeth but very quickly they became established as an ultrasonic scaler which was used to remove deposits from the hard tissues of the tooth. This enabled the soft tissues around the tooth to return to health. The ultrasonic vibrations are generated in a thin metal probe and it is the working tip that is the active component of the instrument. Scanning laser vibrometry has shown that there is much variability in their movement which is related to the shape and cross sectional shape of the probe. The working instrument will also generate cavitation and microstreaming in the associated cooling water. This can be mapped out along the length of the instrument indicating which are the active areas. Ultrasonics has also found use for cleaning often inaccessible or different surfaces including root canal treatment and dental titanium implants. The use of ultrasonics to cut bone during different surgical techniques shows considerable promise. More research is indicated to determine how to maximize the efficiency of such instruments so that they are more clinically effective.
MicroCT allows the complex canal network of teeth to be mapped but does not readily distinguish between structural tissue (dentine) and the debris generated during cleaning. The aim was to introduce a validated approach for identifying debris following routine instrumentation and disinfection.
The mesial canals of 12 mandibular molars were instrumented, and irrigated with EDTA and NaOCl. MicroCT images before and after instrumentation and images were assessed qualitatively and quantitatively.
Debris in the canal space was identified through morphological image analysis and superimposition of the images before and after instrumentation. This revealed that the removal of debris is prohibited by protrusions and micro-canals within the tooth creating areas which are inaccessible to the irrigant. Although the results arising from the analytical methodology did provide measurements of debris produced, biological differences in the canals resulted in variances. Both irrigants reduced debris compared to the control which decreased with EDTA and further with NaOCl. However, anatomical variation did not allow definitive conclusions on which irrigant was best to use although both reduced debris build up.
This work presents a new approach for distinguishing between debris and structural inorganic tissue in root canals of teeth. The application may prove useful in other calcified tissue shape determination.
Remaining debris may contain bacteria and obstruct the flow of irrigating solutions into lateral canal anatomy. This new approach for detecting the amount of remaining debris in canal systems following instrumentation provides a clearer methodology of the identification of such debris.
Pathology of the peri-implant tissues, namely peri-implant mucositis and peri-implantitis are conditions that are often encountered and can threaten the long term survival of the implants.
This study aimed to compare the attitudes of registered specialists in periodontology in Australia and the UK towards aetiology, prevalence, diagnosis and management of mucositis and peri-implantitis.
A validated questionnaire was used and the sample consisted of UK and Australian specialists.
There were differences in the demographics of specialists in the two countries, with the Australian specialists being significantly younger. Most specialists in both countries identified the prevalence of peri-implant pathology between 0-25%. Although there was agreement as to the role of plaque in the aetiopathogenesis of the diseases, UK specialists were more likely to include adverse loading and smoking as etiological factors. There were significant differences in the management of the disease between the groups, including the use of mouth rinses, local and systemic antibiotics. Australians were more likely to use systemic antibiotics than in the UK.
The results suggested that differences in professional demographics, educational resources and market factors, and the absence of consensus treatment standards can significantly affect the treatment modalities patients finally receive.
Oral implantology is the branch of dentistry focused on the reconstruction of missing teeth and their supporting structures with natural or synthetic substitutes. Conventional instruments used during oral implantation exhibit severe operational limitations, especially in the presence of limited surgical access, anatomically delicate bone structures, and proximity to soft tissues, because of the high risk of injury. This paper illustrates the design and performance characteristics of two novel ultrasonic devices developed to improve the implantation process. The working frequency of both systems is in the 25 to 26 kHz range and the acoustic power is modulated in line with the specific operations. The first tuned device presented in this work relies on a planar vibration at its tip to drill holes in bone. The second exploits a longitudinal-flexural composite vibration mode which facilitates the insertion of dental implants into the jawbone. The vibration characteristics of the proposed systems are investigated using finite element (FE) models subsequently validated by experimental modal analysis (EMA). Ultimately, the operational benefits of the investigated devices are supported by clinical evidence.
Ultrasonic scalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the scaler. The vibratory motion of three designs of scaler tip in a water bath has been characterised by laser vibrometry, and compared with the spatial distribution of cavitation around the scaler tips observed using sonochemiluminescence from a luminol solution. The type of cavitation was confirmed by acoustic emission analysed by a 'Cavimeter' supplied by NPL. A node/antinode vibration pattern was observed, with the maximum displacement of each type of tip occurring at the free end. High levels of cavitation activity occurred in areas surrounding the vibration antinodes, although minimal levels were observed at the free end of the tip. There was also good correlation between vibration amplitude and sonochemiluminescence at other points along the scaler tip. 'Cavimeter' analysis correlated well with luminol observations, suggesting the presence of primarily transient cavitation.
Introduction
Targeted Endodontic Microsurgery (TEMS) replaces freehand carbide or diamond bur osteotomy and root end resection with a guided approach using an end-cutting trephine bur rotated within a guide tube. TEMS departs from traditional endodontic microsurgery (EMS) in osteotomy size, control of resection level and bevel, surgical time and resection method, yet the impact of these departures upon clinical outcomes has yet to be assessed. The aim of this study is to assess clinical outcomes of TEMS surgeries at least one year after treatment.
Methods
Potential cases were retrospectively identified from a secure database of all patients that received TEMS in the Air Force Postgraduate Dental School from June 2017 to May 2019 with a postsurgical follow-up exam at 1 year or beyond (23 patients with 24 teeth). Two board certified endodontists completed a calibration exercise prior to assessing radiographs. A retrospective outcomes assessment was conducted considering follow-up clinical and radiographic findings to assign one of three healing designations: complete healing, reductive healing, or failure.
Results
Combined clinical and radiographic data led to 20 designations of complete healing, 2 designations of reductive healing and 2 failures (91.7% success rate). Considered alone, radiographic criteria for complete healing were met for 20 cases, reductive healing by 3 cases with 1 radiographic failure.
Conclusions
This limited retrospective outcomes assessment is an early indication that TEMS guided trephine bur root end resection leads to similar success as is established for freehand carbide and diamond bur resection. Controlled clinical trials with long-term follow-up are warranted.
Objectives
Ultrasonic scalers often cause an uncomfortable feeling to patients during the procedure. This study was conducted to compare patient complaint levels between magnetostrictive (M‐USSC) and piezoelectric ultrasonic scalers (P‐USSC) during supragingival scaling.
Methods
This study enrolled 82 subjects who received supportive periodontal therapy for at least 2 years. At each recall visit, probing pocket depth (PPD), bleeding on probing (BOP) and O’Leary plaque control record (O’PCR) were recorded. Then, supragingival scaling was performed using P‐USSC (Varios or Petit Piezo) at the first visit and M‐USSC (Cavitron) at the second visit. After each treatment, a questionnaire survey was performed using the Wong‐Baker Faces Pain Scale for six items, which included the typical complaints occurring during ultrasonic scaling.
Results
The scores for all the six items related to patient complaints were greater for P‐USSC than for M‐USSC (p < 0.001). Patient complaints such as discomfort, pain, sound, vibration, hyperesthesia and length of treatment time were ameliorated in 74%, 65%, 80%, 67%, 57% and 53% of subjects using M‐USSC, respectively. On the other hand, only <5% of subjects showed deterioration in terms of each complaint.
Conclusion
This study suggested that M‐USSC causes fewer patient complaints during supragingival scaling than P‐USSC. M‐USSC may improve patient motivation and compliance and may contribute towards achieving successful treatment outcomes. However, this result could differ depending on the shape of the tip and the insert and treatment site. Further research will be required under various conditions.
Data sources Non-systematically compiled data.
Study selection No formal in- or exclusion criteria.
Data extraction and synthesis Not described; narrative synthesis.
Results SARS-CoV-2 is near ubiquitously present in saliva samples of infected individuals; the saliva is hence a potential source for infection for both dental professionals and dental patients given possible transmission routes involving saliva-containing aerosol, splatter or droplets for COVID-19.
Conclusions Dental professionals should be aware of that transmission route and should undertake protective measures accordingly.
Purpose:
This study aimed to assess the stability and survival rate of dental implants inserted with different site preparation techniques-piezoelectric inserts versus traditional rotary instruments.
Materials and methods:
Correlative research was located by searching articles in PubMed, EMBASE, and the Cochrane Library. This was accomplished independently by two different reviewers and supplemented by a manual search. Only prospective studies evaluating piezoelectric vs conventional implant site preparation in dental implantation were included in this review. A meta-analysis was performed on the stability and survival rate of implants.
Results:
One thousand fifty-five articles were identified following the search strategy, of which five studies were finally included in this meta-analysis. With regard to the survival rate of implants, there was no statistically significant difference between piezoelectric and conventional implant site preparation (RR = 0.98, 95% CI: 0.94, 1.03; I2 = 0%, P = .86). On the other side, the piezoelectric group had better stability in the eighth week (MD = 4.24, 95% CI: 1.36, 7.12; I2 = 0%, P = .80) and 12th week (MD = 3.33, 95% CI: 0.59, 6.08; I2 = 0%, P = .87) compared with the conventional group.
Conclusion:
Within the limitations of this study, it suggests that the survival rate of implants may not be influenced by the site preparation techniques (piezoelectric vs conventional), but the piezoelectric group may achieve better stability than the conventional group.
Objectives
Current instruments cannot clean in between dental implant threads and effectively remove biofilm from the rough implant surface without damaging it. Cavitation bubbles have the potential to disrupt biofilms. The aim of this study was to see how biofilms can be disrupted using non-contact cavitation from an ultrasonic scaler, imaged inside a restricted implant pocket model using high speed imaging.
Methods
Streptococcus sanguinis biofilm was grown for 7 days on dental implants. The implants were placed inside a custom made restricted pocket model and immersed inside a water tank. An ultrasonic scaler tip was placed 0.5 mm away from the implant surface and operated at medium power or high power for 2 s. The biofilm removal process was imaged using a high speed camera operating at 500 fps. Image analysis was used to calculate the amount of biofilm removed from the high speed images. Scanning electron microscopy was done to visualize the implant surface after cleaning.
Results
Cavitation was able to remove biofilm from dental implants. More biofilm was removed at high power. Scanning electron microscopy showed that the implant surface was clean at the points where the cavitation was most intense. High speed imaging showed biofilm removal underneath implant threads, in areas next to the ultrasonic scaler tip.
Significance
A high speed imaging protocol has been developed to visualize and quantify biofilm removal from dental implants in vitro. Cavitation bubbles from dental ultrasonic scalers are able to successfully disrupt biofilm in between implant threads.
Bacterial biofilm accumulation is problematic in many areas, leading to biofouling in the marine environment and the food industry, and infections in healthcare. Physical disruption of biofilms has become an important area of research. In dentistry, biofilm removal is essential to maintain health. The aim of this study is to observe biofilm disruption due to cavitation generated by a dental ultrasonic scaler (P5XS, Acteon) using a high speed camera and determine how this is achieved. Streptococcus sanguinis biofilm was grown on Thermanox™ coverslips (Nunc, USA) for 4 days. After fixing and staining with crystal violet, biofilm removal was imaged using a high speed camera (AX200, Photron). An ultrasonic scaler tip (tip 10P) was held 2 mm away from the biofilm and operated for 2s. Bubble oscillations were observed from high speed image sequences and image analysis was used to track bubble motion and calculate changes in bubble radius and velocity on the surface. The results demonstrate that most of the biofilm disruption occurs through cavitation bubbles contacting the surface within 2s, whether individually or in cavitation clouds. Cleaning occurs through shape oscillating microbubbles on the surface as well as through fluid flow.
Objectives:
To compare the pain/discomfort experienced by patients in supportive periodontal therapy, following treatment with a piezoelectric ultrasonic scaler, designed for use with warmed water irrigation, and a magnetostrictive ultrasonic scaler.
Methods:
This was a single-centre, randomised, split mouth study with regard to side, and crossover with regard to treatment order. Patients attending general dental practice for supportive periodontal therapy were randomised to receive treatment from one scaler on the left and the other scaler on the right-hand side of the mouth, the left side of the mouth always being treated first. The piezo scaler (Tigon+®) was used with room temperature irrigation for half of the participants (approx 20 °C) and warmed water irrigation (approx36 °C) for the other half. The magnetostrictive scaler (Cavitron Select SPS 30K®) was used with room temperature irrigation (approx 20 °C) only. Participants rated their pain/discomfort, noise and vibration by VAS scale.
Results:
140 participants completed the study. Mean VAS scores for all measures were significantly better for the piezo scaler used with warm irrigation as compared to the magnetostrictive scaler p < 0.001. When both scalers were used with room temperature irrigant, there were no significant differences in the VAS scores between scalers (pain/discomfort, p = 0.68; noise p = 0.2; vibration p = 0.85).
Conclusions:
Participants indicated to statistical significance, less pain/discomfort, noise and vibration when the piezo scaler (Tigon+®) device was used with warmed irrigant, compared to the magnetostrictive scaler (Cavitron Select SPS 30K®). There were no significant differences between the instruments when room temperature irrigant was used.
Clinical significance:
Regular scaling in supportive periodontal therapy, is essential for maintenance of susceptible patients, however it can be painful due to dentine hypersensitivity deterring patients from attending. Using a piezo scaler with warm water improves patient quality of life and subsequent oral health. This may have positive effects on patient attendance.
Isrctn registered:
ISRCTN15573995.
Data sources Cochrane Library, Embase, LILACS, PubMed, SciELO, Scopus databases, endodontic journals and textbooks.
Study selection Two independent reviewers screened the titles, abstracts and/or full-text of the both clinical or in vitro studies that used ultrasonic irrigant activation for management of teeth needing root canal therapy.
Results The study included three clinical studies and 45 in vitro studies. The study reported no evidence of any benefit of ultrasonic activation over needle irrigation in improving the healing rate of apical periodontitis. While the study reported that the evidence for disinfection of the root canal was inconclusive it did show evidence of the efficacy of ultrasonic irrigation over needle irrigation when removal of pulp tissue remnants and hard tissue debris was assessed.
Conclusion The study reported that it was essential that there should be more research into the antimicrobial effect on healing in periapical periodontitis when teeth are treated using ultrasonic activation.
Objectives To evaluate the effectiveness of passive ultrasonic irrigation (PUI) compared with non-activated irrigation (NAI) on periapical healing and root canal disinfection.
Data source A comprehensive search without restrictions was performed in the following systematic electronic databases: PubMed, Scopus, Cochrane, Web of Science, ScienceDirect and OpenGrey. Additional studies were sought through hand-searching in the main endodontic journals.
Data selection We included clinical trials that compared PUI and NAI clinical success and root canal disinfection outcomes. The risk of bias was assessed based on the Cochrane Collaboration common scheme for bias assessment. The power analysis of each study was calculated based on the disinfection rates and sample size, and the evidence was qualified using the GRADE tool.
Data synthesis A total of 346 non-duplicated studies were retrieved in the systematic search. One study that assessed the clinical success rate through periapical radiographic healing evaluation and two studies that evaluated root canal disinfection through bacterial growth were considered eligible. These three studies were classified as low risk of bias. The study evaluating radiographic treatment outcome showed no statistical difference (P >0.05). The studies demonstrated large variability among methodology and, in general, low power and moderate evidence. Inconclusive results were reported regarding root canal disinfection when comparing PUI to NAI strategies.
Conclusions Based on the findings, there was no evidence of effectiveness improvement on periapical healing and bacterial disinfection that supports the use of PUI over the NAI in clinical practice.
PURPOSE: Assess prevalence of self-reported hearing difficulties among experienced dental hygienists who have been practicing for a minimum of 20 years and explore the relationship between hearing difficulties and occupational noise exposure from ultrasonic scalers. METHODS: A 19-item survey was mailed to a random sample of 1,067 dental hygienists who had obtained their California licenses between 1972 and 1992. To estimate the prevalence of hearing difficulty, binomial proportion and associated 95% confidence interval are presented. Logistic regression model of hearing difficulty was used to assess an association with ultrasonic scaler use. RESULTS: Response rate was 35% (n=372/1,067). The prevalence of self-reported hearing difficulty was 40% (95% confidence interval, 35 to 44%). Of the 17% (95% confidence interval, 14 to 21%) of respondents that reported hearing difficulty due to ultrasonic scalers, most (91%) reported that their hearing difficulty was confirmed by an audiologist. Respondents with hearing difficulty due to scalers were 2-times (odds ratio: 2.0, 95% confidence interval, 1.1 to 3.6, p=0.03) more likely to report significantly higher scaler use than those who did not have hearing difficulty after adjusting for age and other potential causes of hearing difficulties. CONCLUSION: The prevalence of hearing difficulty at 40% among dental hygienists with an average age of 56 years was considerably higher than the reported national average at 17% for adults 70 years or older. Long-term noise exposure to dental equipment, such as ultrasonic scalers, may contribute to hearing difficulties among experienced dental hygienists. Ear protection is suggested as a preventive measure while using noisy dental equipment.
Bacterial biofilms are a cause of contamination in a wide range of medical and biological areas. Ultrasound is a mechanical energy that can remove these biofilms using cavitation and acoustic streaming, which generate shear forces to disrupt biofilm from a surface. The aim of this narrative review is to investigate the literature on the mechanical removal of biofilm using acoustic cavitation to identify the different operating parameters affecting its removal using this method. The properties of the liquid and the properties of the ultrasound have a large impact on the type of cavitation generated. These include gas content, temperature, surface tension, frequency of ultrasound and acoustic pressure. For many of these parameters, more research is required to understand their mechanisms in the area of ultrasonic biofilm removal, and further research will help to optimise this method for effective removal of biofilms from different surfaces.
Introduction: The aim of this study was to systematically review the evidence on the cleaning and disinfection of root canals and the healing of apical periodontitis when ultrasonic irrigant activation is applied during primary root canal treatment of mature permanent teeth as compared to syringe irrigation.
Methods: An electronic search was conducted in Cochrane Library, EMBASE, LILACS, PubMed, SciELO, and Scopus using both free-text keywords and controlled vocabulary. Additional studies were sought through hand-searching of endodontic journals and textbooks. The retrieved studies were screened by two reviewers according to predefined criteria. Included studies were critically appraised and the extracted data were arranged in tables.
Results: The electronic and hand search retrieved 1966 titles. Three clinical studies and 45 in vitro studies were included in this review. Ultrasonic activation didn’t improve the healing rate of apical periodontitis compared to syringe irrigation after primary root canal treatment of teeth with a single root canal. Conflicting results were reported by the in vitro microbiological studies. Ultrasonic activation was more effective than syringe irrigation in the removal of pulp tissue remnants and hard tissue debris based on both clinical and in vitro studies. Ultrasonic activation groups were possibly favored in 13 studies, whereas syringe irrigation groups may have been favored in 3 studies.
Conclusions: The level of the available evidence was low, so no strong clinical recommendations could be formulated. Future studies should focus on the antimicrobial effect and healing of apical periodontitis in teeth with multiple root canals.
Background
Intact hearing is essential for medical students and physicians for communicating with patients and appreciating internal sounds with a stethoscope. With the increased use of (PMSs), they are exposed to high sound levels and are at a risk of developing hearing loss. The effect of long term personal music system (PMS) usage on auditory sensitivity has been well established. Our study has reported the immediate and short term effect of PMS usage on hearing especially among medical professionals.
Objective
To assess the effect of short term PMS usage on distortion product otoacoustic emissions (DPOAE) among medical professionals.
Materials and Method
34 medical students within the age range of 17–22 years who were regular users of PMS participated in the study. All participants had hearing thresholds <15 dBHL at audiometric octave frequencies. Baseline DPOAEs were measured in all participants after 18 h of non-usage of PMS. One week later DPOAEs were again measured after two hours of continuous listening to PMS. DPOAEs were measured within the frequency range of 2 to 12 kHz with a resolution of 12 points per octave. Output sound pressure level of the PMS of each participant was measured in HA-1 coupler and it was converted to free field SPL using the transformations of RECD and REUG.
Results
Paired sample t test was used to investigate the main effect of short term music listening on DPOAE amplitudes. Analysis revealed no significant main effect of music listening on DPOAE amplitudes at the octave frequencies between 2 to 4 KHz (t67 = −1.02, P = 0.31) and 4 to 8 KHz (t67 = 0.24, P = 0.81). However, there was a small but statistically significant reduction in DPOAE amplitude (t67 = 2.10, P = 0.04) in the frequency range of 9 to 12 kHz following short term usage of PMS. The mean output sound pressure level of the PMS was 98.29.
Conclusion
Short term exposure to music affects the DPOAE amplitude at high frequencies and this serves as an early indicator for noise induced hearing loss (NIHL). Analysis of output sound pressure level suggests that the PMSs of the participants have the capability to induce hearing loss if the individual listened to it at the maximum volume setting. Hence, the medical professionals need to be cautious while using PMS.
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<0.007) and increased with concentration (P<0.014). The IrriSafe file outperformed significantly the K-file in removing hydrogel (P<0.05). Up to 64% of the total hydrogel volume was removed after 20 s. The IrriSafe file typically outperformed the K-file in generating streaming. The oscillatory velocities were higher inside the lateral canal 3 mm compared to 6 mm from WL, and were higher for NaOCl than for saturated water, which in turn was higher than for degassed water.
Conclusions:
Measurements of cavitation and acoustic streaming have provided insight into their contribution to cleaning. Significant differences in cleaning, cavitation and streaming were found depending on the file type and size, lateral canal location and irrigant used. In general, the IrriSafe file outperformed the K-file, and NaOCl performed better than the other irrigants tested. The cavitation and streaming measurements revealed that both contributed to hydrogel removal and both play a significant role in root canal cleaning. This article is protected by copyright. All rights reserved.
Objectives:
Functionalised silica sub-micron particles are being investigated as a method of delivering antimicrobials and remineralisation agents into dentinal tubules. However, their methods of application are not optimised, resulting in shallow penetration and aggregation. The aim of this study is to investigate the impact of cavitation occurring around ultrasonic scalers for enhancing particle penetration into dentinal tubules.
Methods:
Dentine slices were prepared from premolar teeth. Silica sub-micron particles were prepared in water or acetone. Cavitation from an ultrasonic scaler (Satelec P5 Newtron, Acteon, France) was applied to dentine slices immersed inside the sub-micron particle solutions. Samples were imaged with scanning electron microscopy (SEM) to assess tubule occlusion and particle penetration.
Results:
Qualitative observations of SEM images showed some tubule occlusion. The particles could penetrate inside the tubules up to 60μm when there was no cavitation and up to ∼180μm when there was cavitation.
Conclusions:
The cavitation bubbles produced from an ultrasonic scaler may be used to deliver sub-micron particles into dentine. This method has the potential to deliver such particles deeper into the dentinal tubules.
Clinical significance:
Cavitation from a clinical ultrasonic scaler may enhance penetration of sub-micron particles into dentinal tubules. This can aid in the development of novel methods for delivering therapeutic clinical materials for hypersensitivity relief and treatment of dentinal caries.
Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies
Purpose:
The aim of this study was to evaluate the cleaning effectiveness of implant prophylaxis instruments on polished and acid-etched implant surfaces.
Materials and methods:
Biofilm layers of Streptococcus mutans were grown on a total of 80 titanium disks; 40 disks were polished and 40 were acid-etched. Five disks of each surface were cleaned using each of seven implant prophylaxis instruments: (1) manual plastic curette, (2) manual carbon fiber-reinforced plastic (CFRP) curette, (3) sonic-driven prophylaxis brush, (4) rotating rubber cup with prophylaxis paste, (5) sonic-driven polyether ether ketone (PEEK) plastic tip, (6) ultrasonic-driven PEEK plastic tip, and (7) air polishing with amino acid (glycine) powder. Ten disks (five of each surface type) served as controls. After cleaning, the surfaces with remaining bacteria were assessed by light microscopy. Statistical analyses of the results were performed with one-way and two-way analyses of variance with Bonferroni-Dunn multiple comparisons post hoc analysis (α = .05).
Results:
The cleaning effectiveness of the plastic curette was significantly lower than those of all machine-driven instruments on the polished surface. Significantly lower cleaning effectiveness occurred with the CFRP curette compared to the prophylaxis brush and to both oscillating PEEK plastic tips on the polished surface. The rubber cup provided less cleaning effectiveness compared to the ultrasonic PEEK plastic tip and air polishing on the acid-etched surface. Superior results, with less than 4% of the biofilm remaining, were obtained for both oscillating PEEK plastic tips and air polishing on both implant surfaces. The cleaning ability of the prophylaxis brush, rubber cup, and ultrasonic PEEK plastic tip differed significantly between both surface structures.
Conclusions:
Cleaning effectiveness, ie, less than 4% of the biofilm remaining, was not observed with all tested implant prophylaxis instruments. The cleaning ability of the devices depended on the implant surface structure.
To introduce and characterise a reproducible hydrogel as a suitable biofilm-mimic in endodontic research. To monitor and visualise the removal of hydrogel from a simulated lateral canal and isthmus for: i) Ultrasonic Activated Irrigation (UAI) with water, ii) UAI with NaOCl, iii) NaOCl without UAI.
A rheometer was used to characterise the viscoelastic properties and cohesive strength of the hydrogel for suitability as a biofilm mimic. The removal rate of the hydrogel from a simulated lateral canal or isthmus was measured by high speed imaging operating at frame rates from 50 to 30,000 fps.
The hydrogel demonstrated viscoelastic behaviour with mechanical properties comparable to real biofilms. UAI enhanced the cleaning effect of NaOCl in isthmi (P<0.001) and both NaOCl and water in lateral canals (P<0.001). A greater depth of cleaning was achieved from an isthmus (P=0.009) than from a lateral canal with UAI, and also at a faster rate for the first 20 seconds. NaOCl without UAI resulted in a greater depth of hydrogel removal from a lateral canal than an isthmus (P<0.001). The effect of UAI was reduced when stable bubbles were formed and trapped in the lateral canal. Different removal characteristics were observed in the isthmus and the lateral canal, with initial highly unstable behaviour followed by slower viscous removal inside the isthmus.
The biofilm-mimic hydrogel is reproducible, homogenous and can be easily applied and modified. Visualisation of its removal from lateral canal anatomy provides insights into the cleaning mechanisms of UAI for a biofilm-like material. Initial results showed that UAI improves hydrogel removal from the accessory canal anatomy, but the creation of stable bubbles on the hydrogel-liquid interface may reduce the cleaning rate. This article is protected by copyright. All rights reserved.
This multicenter case series introduces an innovative ultrasonic implant site preparation (UISP) technique as an alternative to the use of traditional rotary instruments. A total of 3,579 implants were inserted in 1,885 subjects, and the sites were prepared using a specific ultrasonic device with a 1- to 3-year follow-up. No surgical complications related to the UISP protocol were reported for any of the implant sites. Seventy-eight implants (59 maxillary, 19 mandibular) failed within 5 months of insertion, for an overall osseointegration percentage of 97.82% (97.14% maxilla, 98.75% mandible). Three maxillary implants failed after 3 years of loading, with an overall implant survival rate of 97.74% (96.99% maxilla, 98.75% mandible).
The power of ultrasonic vibrations has been harnessed in the field of dentistry—evolving in its use and purpose—for just over 60 years. The first section of this review describes the evolution and various applications of ultrasound in dentistry, and examines in detail the ultrasonic tools that have been developed for endodontic purposes. The second section of this review describes the use of ultrasonics during specific endodontic procedures, from access to obturation, incorporating as much as possible the most recent and relevant research available to date.
Some dentists who have employed the ultrasonic method of preparing cavities and patients who have experienced its use express favorable comment. Pulps of vital permanent teeth appear to be unaffected, but operations on children's teeth should not be attempted until future research indicates no ill effects.The original cost of the unit, its size, and the fact that it is strictly an adjunct to the present armamentarium of the dentist will probably be a deterrent to its acceptance. Cleaning and attaching the tips, tuning the machine, and applying the correct load while operating are discouraging aspects to the beginner.The ultrasonic method of cutting carious or sound enamel, carious or sound dentine, and certain types of restorative materials does not approach the effectiveness that can be demonstrated with the ultra high-speed rotational instruments.
In the short span of three years, the ultrasonic dental instrument has been extensively investigated. Today, it is an instrument advantageous to the patient and dentist. Fortunately, all new developments were made in the expendable Cavitips and the power unit and handpiece remained the same. It is conceivable that additional improvements will follow.Cavity preparation by the ultrasonic method is efficient in relation to the time required, and it is effective in making classical cavity preparations.The greatest advantage of the ultrasonic unit is to the patient. Cavity preparation by this method is practically noiseless, vibrationless, heatless, and is well tolerated without local anesthesia.
Aim:
(i) To quantify in a simulated root canal model the file-to-wall contact during ultrasonic activation of an irrigant and to evaluate the effect of root canal size, file insertion depth, ultrasonic power, root canal level and previous training, (ii) To investigate the effect of file-to-wall contact on file oscillation.
Methodology:
File-to-wall contact was measured during ultrasonic activation of the irrigant performed by 15 trained and 15 untrained participants in two metal root canal models. Results were analyzed by two 5-way mixed-design anovas. The level of significance was set at P < 0.05. Additionally, high-speed visualizations, laser-vibrometer measurements and numerical simulations of the file oscillation were conducted.
Results:
File-to-wall contact occurred in all cases during 20% of the activation time. Contact time was significantly shorter at high power (P < 0.001), when the file was positioned away from working length (P < 0.001), in the larger root canal (P < 0.001) and from coronal towards apical third of the root canal (P < 0.002), in most of the cases studied. Previous training did not show a consistent significant effect. File oscillation was affected by contact during 94% of the activation time. During wall contact, the file bounced back and forth against the wall at audible frequencies (ca. 5 kHz), but still performed the original 30 kHz oscillations. Travelling waves were identified on the file. The file oscillation was not dampened completely due to the contact and hydrodynamic cavitation was detected.
Conclusion:
Considerable file-to-wall contact occur-red during irrigant activation. Therefore, the term 'Passive Ultrasonic Irrigation' should be amended to 'Ultrasonically Activated Irrigation'.
During a root canal treatment, an antimicrobial fluid is injected into the root canal to eradicate all bacteria from the root canal system. Agitation of the fluid using an ultrasonically vibrating miniature file results in a significant improvement in the cleaning efficacy over conventional syringe irrigation. Numerical analysis of the oscillation characteristics of the file, modeled as a tapered, driven rod, shows a sinusoidal wave pattern with an increase in amplitude and decrease in wavelength toward the free end of the file. Measurements of the file oscillation with a scanning laser vibrometer show good agreement with the numerical simulation. The numerical model of endodontic file oscillation has the potential for predicting the oscillation pattern and fracture likeliness of various file types and the acoustic streaming they induce during passive ultrasonic irrigation.
Abstract The effects of ultrasonic and sonic sealers on the subgingival microflora were investigated in vitro and in vivo. In the in vitro investigation, 27 plaque samples collected from periodontal pockets were submitted to ultrasonic and sonic vibrations for 10, 30 and 60 s. Bacterial suspensions were examined by dark-field microscopy to detect qualitative changes and cultured to evaluate the total number of cultivable bacteria. Microscopic counts following both instrumentations showed a decrease in the proportions of spirochetes and motile rods and an increase in the % of coccoids and rods. The changes were directly related to the time-period of instrumentation. Comparison between both types of instrumentation showed significant differences and more pronounced changes were observed with the ultrasonic than the sonic sealer. Spirochetes and motile rods were reduced to approximately 0.1% after ultrasonic treatment versus 24.7% after sonic instrumentation. Cultural observations showed a marked increase in total number of colony-forming units following both treatments. The clinical investigation included 66 periodontal pockets which were instrumented subgingivally for 10 and 30 s with ultrasonic or sonic sealers. Qualitative changes were similar to those observed in vitro, i.e., reduction in spirochete and motile rod counts as well as the other morphotypes with an increase in coccoid cells. Total counts of bacteria were reduced following debridement. No difference in the microscopic or cultural data was found between ultrasonic and sonic instrumentation.
Objectives:
Ultrasonic surgery is an increasingly popular technique for cutting bone, but little research has investigated how the ultrasonic tip oscillations may affect the cuts they produce in bone. The aim of this investigation was to evaluate the oscillation and cutting characteristics of an ultrasonic surgical device.
Materials and methods:
A Piezosurgery 3 (Mectron, Carasco, Italy) ultrasonic cutting system was utilised with an OP3 style tip. The system was operated with the tip in contact with porcine bone samples (loads of 50 to 200 g) mounted at 45° to the vertical insert tip and with a water flow of 57 ml/min. Tip oscillation amplitude was determined using scanning laser vibrometry. Bone surfaces defects were characterised using laser profilometry and scanning electron microscopy.
Results:
A positive relationship was observed between the magnitude of tip oscillations and the dimensions of defects cut into the bone surface. Overloading the tip led to a reduction in oscillation and hence in the defect produced. A contact load of 150 g provided the greatest depth of cut. Defects produced in the bone came from two clear phases of cutting.
Conclusions:
The structure of the bone was found to be an important factor in the cut characteristics following piezosurgery.
Clinical relevance:
Cutting of bone with ultrasonics is influenced by the load applied and the setting used. Care must be used to prevent the tip from sliding over the bone at low loadings.
The quantitative bactericidal efficiency of ultrasonics with and without a cidal agent, as an endodontic irrigation system, was compared with the use of four test microorganisms. Sodium hypochlorite and potentiated acid 1,5 pentanedial were the cidal irrigation solutions used. A sonosynergistic system for endodontic irrigation is described.
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.
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).
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<0.02). Using SEM, it was observed that modifications to the implant surface had occurred following instrumentation with the plastic-tipped insert. Debris was also visible around the defects.
Metal scalers produce defects in titanium implant surfaces and load and power are important factors in the damage caused. Plastic-coated scaler probes cause minimal damage to implant surfaces and have a polishing action but can leave plastic deposits behind on the implant surface.
Hig hintensity focused ultrasound (HIFU) has been applied for drug delivery in various disease conditions. Delivery of antibacterial-nanoparticles into dental hard tissues may open up new avenues in the treatment of dental infections. However, the basic mechanism of bubble dynamics, its characterization, and working parameters for effective delivery of nanoparticles, warrants further understanding. This study was conducted to highlight the basic concept of HIFU and the associated bubble dynamics for the delivery of nanoparticles. Characterization experiments to deliver micro-scale particles into simulated tubular channels, activity of ultrasonic bubbles, and pressure measurement inside the HIFU system were conducted. Subsequently, experiments were carried out to test the ability of HIFU to deliver nanoparticles into human dentine using field emission scanning electron micrographs (FESEM) and elemental dispersive X-ray analysis (EDX). The characterization experiments showed that the bubbles collapsing at the opening of tubular channels were able to propel particles along their whole length. The pressure measured showed sufficient negative and positive pressure suggesting that the bubble grew to a certain size before collapsing, thus enabling the particles to be pushed. The FESEM and EDX analysis highlighted the ability of HIFU to deliver nanoparticles deep within the dentinal tubules. This study highlighted the characteristics and the mechanism involved of the bubbles generated by the HIFU and their capability to deliver nanoparticles.
Passive ultrasonic irrigation may be used to improve bacterial reduction within the root canal. The technique relies on a small file being driven to oscillate freely within the canal and activating an irrigant solution through biophysical forces such as microstreaming. There is limited information regarding a file's oscillation patterns when operated while surrounded by fluid as is the case within a canal root.
Files of different sizes (#10 and #30, 27 mm and 31 mm) were connected to an ultrasound generator via a 120 degrees file holder. Files were immersed in a water bath, and a laser vibrometer set up with measurement lines superimposed over the files. The laser vibrometer was scanned over the oscillating files. Measurements were repeated 10 times for each file/power setting used.
File mode shapes are comprised of a series of nodes/antinodes, with thinner, longer files producing more antinodes. The maximum vibration occurred at the free end of the file. Increasing generator power had no significant effect on this maximum amplitude (p > 0.20). Maximum displacement amplitudes were 17 to 22 microm (#10 file, 27 mm), 15 to 21 microm (#10 file, 31 mm), 6 to 9 microm (#30 file, 27 mm), and 5 to 7 microm (#30, 31 mm) for all power settings. Antinodes occurring along the remaining file length were significantly larger at generator power 1 than at powers 2 through 5 (p < 0.03).
At higher generator powers, energy delivered to the file is dissipated in unwanted vibration resulting in reduced vibration displacement amplitudes. This may reduce the occurrence of the biophysical forces necessary to maximize the technique's effectiveness.
Ultrasonic scalers are used in dentistry for removing mineralised plaque, known as calculus, from tooth surfaces. Though there is much information relating to the longitudinal vibrations of scaler probes, corresponding lateral data is limited. Understanding the lateral motion of ultrasonic probes is essential as, when used correctly, this motion will contribute to the cleaning process as well as to any damage caused to tooth surfaces. In this work we demonstrate the use of a single-axis scanning laser vibrometer, in conjunction with a mirror, to evaluate simultaneously the longitudinal and lateral motion of dental scaler probes oscillating at ultrasonic frequencies (approximately 30 kHz). Node/antinode patterns along the probe length were observed, as was an elliptical motion along the length of the probe. Application of a load to the tip of the instrument modified the vibration pattern of the whole probe. This technique seems an important step towards better characterisation of the three-dimensional movement of oscillating ultrasonic scaler probes, particularly when probes are contacted against teeth. Understanding the three-dimensional probe motion and how this is affected by contact with tooth surfaces may lead to future instrument designs with improved cleaning efficiency whilst minimising potential tooth damage.
This review has highlighted the importance of standardizing future investigations to enable more meaningful interstudy comparisons to be made. This report also makes recommendations for factors that should be considered and incorporated into future investigations, both in vitro and in vivo, in order to achieve more standardization. These recommendations are listed below.
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.