Ultrasonic scaler oscillations and tooth-surface defects

Effects of a new magnetostrictive ultrasonic scaler and a traditional piezoelectric ultrasonic scaler on root surfaces and patient complaints

Tooth wear and pain are the primary concerns of patients undergoing periodontal scaling. The aims of this study were to compare the effects of a new magnetostrictive ultrasonic scaler and a traditional piezoelectric ultrasonic scaler on tooth surface roughness and calculus removal and to determine their impacts on patient discomfort during supragingival cleaning. This article had two parts: an in vitro study and a clinical study. In the in vitro study, thirty teeth with subgingival calculus were randomly assigned to two scaling treatment groups: magnetostrictive scalers (n = 15) and piezoelectric scalers (n = 15). Surface roughness measurements were taken at baseline and after scaling, and the root samples were visualised by SEM after scaling. Additionally, a single-centre randomised split-mouth clinical trial was conducted. Eighty-five participants diagnosed with chronic gingivitis or periodontitis were randomly assigned to receive supragingival scaling. The magnetostrictive scaler was used in half of the mouths (n = 85), and the piezoelectric scaler was used in the other half of the mouths (n = 85). Data on pain, noise, and vibration were collected using a VAS questionnaire, and the operating time was recorded. In both in vitro and clinical studies, magnetostrictive scalers were reported to be more effective than piezoelectric scalers in removing dental deposits (P < 0.05). Additionally, the root surface after scaling with the magnetostrictive scaler was smoother than that after scaling with the piezoelectric scaler in the in vitro study (P = 0.02). SEM examination also revealed that fewer dental materials were lost after instrumentation with the magnetostrictive scaler than after instrumentation with the piezoelectric scaler. Piezoelectric scalers caused less discomfort to patients in terms of pain, noise, and vibration than magnetostrictive scalers (P < 0.05). According to this clinical study, the magnetostrictive scaler caused more discomfort during supragingival scaling than the piezoelectric scaler. Moreover, the magnetostrictive scaler was also more efficient and produced a smoother root surface with less material loss after scaling than the piezoelectric scaler, as demonstrated in the in vitro study.

Assessing the effect of piezoelectric ultrasonic scaler tip wear on root surface roughness under influence of various working parameters: A profilometric and atomic force microscopic study

Background

Assessing the effect of scaler tip wear on the root surface roughness using piezoelectric ultrasonic scaling device under influence of various working parameters, i.e. power setting, lateral force, and instrumentation time.

Materials and Methods

An experimental study was conducted using 160 single-rooted tooth samples divided into two groups of new (n = 80) and worn tips (n = 80). Samples were prepared to examine the root surface roughness after being instrumented by new and worn piezoelectric ultrasonic tips (8 new/8 worn) at different parameters. The erosion ratio (ER) of the new/worn tip was examined under an atomic force microscope and roughness over root surface was measured by a contact surface profilometer. One-way analysis of variance test, post hoc Tukey's test, and independent t-test were used for intragroup, pair-wise multiple comparisons and intergroup comparison of average roughness (Ra) value.

Results

A statistically significant difference was found between the ER of new and worn scaler tips (P < 0.001). Intragroup comparison between subgroups 1 and 8 showed a higher Ra value in both the groups (P < 0.005). There was a significantly higher Ra value of worn tips compared to new tips (P < 0.05). Significantly higher mean Ra value was shown when lateral force changed from 50 g to 100 g (P < 0.005).

Conclusions

Increasing value of power setting, lateral force, and instrumentation time caused more surface roughness in worn-out scaler tips compared to new scaler tips. Lateral force and instrumentation time proved to be a major factor influencing surface roughness.

Dental Pulp Stem Cells and Current in vivo Approaches to Study Dental Pulp Stem Cells in Pulp Injury and Regeneration

Dental pulp stem cells (DPSCs) have garnered significant interest in dental research for their unique characteristics and potential in tooth development and regeneration. While there were many studies to define their stem cell-like characteristics and osteogenic differentiation functions that are considered ideal candidates for regenerating damaged dental pulp tissue, how endogenous DPSCs respond to dental pulp injury and supply new dentin-forming cells has not been extensively investigated in vivo. Here, we review the recent progress in identity, function, and regulation of endogenous DPSCs and their clinical potential for pulp injury and regeneration. In addition, we discuss current advances in new mouse models, imaging techniques, and its practical uses and limitations in the analysis of DPSCs in pulp injury and regeneration in vivo.

Effectiveness of various irrigant activation techniques on the penetration of sodium hypochlorite into lateral canals of mature permanent teeth: A systematic review and meta-analysis

Objective

This review aimed to systematically review the effectiveness of various irrigant activation techniques (IATs) on the penetration of sodium hypochlorite (NaOCl) into the lateral canals of mature permanent teeth.

Methods

Electronic databases including MEDLINE (via PubMed), Scopus, ProQuest, and Cochrane Library were searched to identify laboratory studies evaluating the penetration of NaOCl into lateral canals following the use of apical negative pressure irrigation (ANP), passive ultrasonic irrigation (PUI), sonic irrigation (SI), and/or manual dynamic activation (MDA) techniques. Meta-analysis was performed for individual IATs in comparison with CNI into the lateral canals of both straight and curved root canals. On the basis of the previous literature and parameters, the risk of bias of the selected studies was evaluated with the help of a customized tool.

Results

Of the 983 records screened, 12 studies were selected to include in the systematic review, and 10 studies were selected for the meta-analysis. The total quality assessment across the included studies indicated a high quality (83.3%). Overall, the meta-analysis demonstrated IATs had significant improvement in the penetration of NaOCl into the lateral canals of straight canals (34.3%) over CNI. The subgroup analysis of individual IATs demonstrated PUI (60.9%) to be superior in the penetration into lateral canals of straight canals.

Conclusions

IATs improved the irrigant penetration into lateral canals and therefore their use during routine endodontic practice is recommended. In straight canals, PUI is the most effective IAT followed by ANP, SI, and MDA techniques.

Effect of passive ultrasonic irrigation on hard tissue debris removal: a systematic review and meta-analysis

Accumulated hard tissue debris (AHTD) in root canal irregularities may negatively impact adequate root canal disinfection. In light of this, the efficacy of passive ultrasonic irrigation (PUI) to reduce AHTD has been largely studied in in vitro studies, which have adopted different analytic methods of varying accuracy to determine the extent of AHTD more correctly. Therefore, the aim of this study was to compare how well PUI and non-activated irrigation (NAI) systems perform in reducing AHTD during final irrigation protocols, based exclusively on studies whose analyses used microCT scanning. A systematic search of the studies published up to April 2020 was performed using MeSH terms and free terms, in the following databases: PubMed, Scopus, Web of Science, BVS (Lilacs and BBO) and Embase. The inclusion criteria consisted of laboratory studies that evaluated the amount of AHTD, and compared PUI with NAI protocols using microCT analysis. The risk of bias in the selected studies was assessed critically by two reviewers. A meta-analysis was performed using the RevMan software program (P<0.05), and included studies providing the standardized mean difference (SMD), using a fixed effect model, and adopting a confidence interval of 95%. In all, 3495 studies were identified, three of which met the inclusion criteria. All three were considered as having a low risk of bias. The meta-analysis comparing the ability of PUI and NAI protocols to remove hard tissue debris showed a higher percentage of AHTD reduction (P<0.01) for PUI, with a confidence interval of 1.41 [0.79, 2.02]. The heterogeneity among the studies was 82% (I2). Considering the limitations of the present study, this systematic review and meta-analysis showed that PUI was more effective than NAI in removing hard tissue debris, based exclusively on studies that used microCT scanning to provide a more precise analysis of the two techniques used. The findings presented in the present study reinforce the concept that PUI can increase residue removal and improve the cleanliness of the root canal in endodontic treatments.

Reduction of dual-species biofilm after sonic- or ultrasonic-activated irrigation protocols: A laboratory study

AIM

To evaluate the antibacterial effect of sonic- and ultrasonic-activated irrigation on bacterial reduction of a dual-species biofilm in root canals compared to nonactivated irrigation in a laboratory study.

METHODOLOGY

Two hundred and forty extracted human single-rooted maxillary anterior teeth were divided into two main groups (G, n = 120) according to the initial preparation size of the root canal (G1: size 25, 0.06 taper, G2: size 40, 0.06 taper). Root canals were inoculated with Enterococcus faecalis and Streptococcus oralis. After 5 days, G1 received combined instrumentation (up to size 40, 0.06 taper) and irrigation/activation, whereas G2 received solely irrigation/activation protocols. In both groups, irrigation was performed with sodium hypochlorite (NaOCl 1%) or physiological saline (NaCl 0.9%), using nonactivated syringe irrigation, sonic activation (2 x 30 s) or ultrasonic activation (2 x 30 s). Logarithmic reduction factors (LRFs) of colony-forming units were analysed separately for dentine-adherent and planktonic bacteria immediately after irrigation/activation protocols (time-point 1) or after 5 days of further incubation (time-point 2) by analysis of variance (anova) and post hoc tests (Tukey's HSD, t-test). The significance level was set at 0.05.

RESULTS

In G1 subgroups (combined instrumentation with irrigation/activation), LRFs were significantly affected by the applied irrigation solution (p < .0001), but not by the activation method (p > .05; anova). In G2 subgroups (solely irrigation/activation), both, irrigant solution and activation, significantly affected LRFs (p < .0001, anova). Sonic activation resulted in significantly higher LRFs than ultrasonic activation (p < .0001) which had significantly greater reductions than nonactivated irrigation (p < .05; Tukey's HSD). At T2, strong bacterial regrowth was observed in all groups; however, a significant bacterial reduction was detected for factors instrumentation, irrigant solution and activation (p < .0001; anova). Similar LRFs were found for dentine-adherent and planktonic bacterial cells in all groups (r = 0.91 at T1, r = 0.8 at T2).

CONCLUSIONS

In this laboratory study on extracted maxillary anterior teeth high-frequency sonic activation resulted in a greater bacterial reduction compared to ultrasonic activation in groups receiving solely irrigation/activation protocols; however, irrigation using NaOCl and ultrasonic activation also contributed significantly to bacterial reduction compared to the control groups.

Influence of scaler tip design on root surface roughness, tooth substance loss and patients' pain perception: an in vitro and a randomised clinical trial

Background

The influence of scaler tip design on root surface roughness, tooth substance loss and patients’ pain perception is investigated.

Methods

This article was divided into the following parts: Part 1 Surface roughness and substance loss: an in vitro study, which involves intact extracted teeth sectioned and treated using a piezoelectric ultrasonic device (PM200 EMS Piezon, Switzerland) with a conventional scaler tip (FS-407) and a Perio Slim (PS) scaler tip (Perio Slim DS-016A). All sectioned samples for tooth surface roughness (n = 20) and tooth substance loss (n = 46) analyses were measured and compared using a 3D surface texture analyser and scanning electron microscope (SEM) respectively, at baseline and following scaling. Part 2 Pain Perception: a clinical study, which was a split mouth study design including 30 participants with gingivitis and/or mild chronic periodontitis; treated with supra-gingival scaling from teeth #13 to #23. Subjects were randomised to group A or group B. Group A was treated first with PS scaler tips, whereas group B was treated first with conventional scaler tips. Pain perception was recorded using the visual analogue scale (VAS).

Results

In vitro study: both scaler tips caused significant reduction in root substance roughness after scaling (p < 0.05), but no significant difference between the two scaler tips (p > 0.05) was observed. The PS scaler tip caused statistically significantly less root substance loss (p < 0.05) when the initial thickness of the tooth was < 1000 µm. Clinical study: the participants reported significantly lesser pain score during scaling using the PS scaler tip (median: 3) than when using the conventional scaler tip (median: 5) (p < 0.05).

Conclusions

In the in vitro study, using a slim scaler tip design causes less tooth substance loss compared to a wider scaler tip design. In the clinical study, less pain was observed compared than a wide (conventional) scaler tip design.

Influence of one-step professional mechanical tooth cleaning pastes on surface roughness and morphological features of tooth substrates and restoratives

PURPOSE

This study investigated the influence of professional mechanical tooth cleaning (PMTC) pastes on the surface texture of different subject materials.

METHODS

Two one-step PMTC pastes, Clinpro Cleaning Paste for PMTC (CP) and PRG Pro-Care Gel (PG), and multiple-step PMTC pastes, Merssage Regular (MR), Merssagge Fine (MF), and Merssage Plus (MP), were used. For comparison, PMTC was performed using distilled water without paste (DW). The subjected materials used were bovine enamel (ENA) and dentin (DEN), a resin composite (FSU), and lithium disilicate (IEC). The prepared specimens were polished using a #2000-grit silicon carbide paper. PMTC was performed using a brush at 1,000 rpm for 15 s.

RESULTS

The surface roughness (Ra) values of the specimens before and after PMTC were measured by laser scanning microscopy. The Knoop hardness number (KHN) of the subjected material was obtained. The types of PMTC pastes and subject materials had a significant influence on the Ra values and KHN. For the majority of subject materials, the descending order of Ra values after PMTC was MR > MF > CP > PG > MP > DW. The descending order of KHN of the materials was IEC > ENA > FSU > DEN.

CONCLUSION

Although one-step PMTC pastes appeared to be effective, it is important to consider the subject material during PMTC.

The effectiveness of an actuator-driven pulsed water jet for the removal of artificial dental calculus: a preliminary study

Background

While hand and ultrasonic scalers are the primary tools used for the removal of dental calculus in periodontal treatment, many studies have shown that they also damage the enamel surface. We have developed a novel actuator-driven pulsed water jet (ADPJ) system, which has the ability to selectively remove materials depending on their stiffness. Considering the different material properties between teeth and dental calculus, it might be possible to develop the ADPJ to remove dental calculus without damage to the tooth’s enamel surface using a suitable jet pressure. Therefore, the aim of this study was to assess the effectiveness of the ADPJ in removing dental calculus, and the surface features of the teeth after its use.

Methods

A total of 93 artificial teeth coated with artificial dental calculus were examined in this study. The weights of 90 teeth were measured before and after the use of ADPJ, which had an applied voltage setting of 150, 200, or 240 V. The three remaining teeth were instrumented with a conventional hand scaler, ultrasonic scaler, or ADPJ (set at 240 V). Damage to the artificial tooth surfaces was evaluated using 5% Evans blue dye under an optical microscope. Furthermore, apatite pellets, which are utilized as experimental substitutes for natural teeth, were assessed after the use of ADPJ and both conventional scalers.

Results

The ADPJ significantly reduced the amount of artificial calculus, and the removal rate was dependent on the applied voltage. No damage was observed on the surface of the artificial tooth and apatite pellet following the use of ADPJ, in contrast to the conventional scalers.

Conclusions

The results of this study demonstrate the in vitro effectiveness of ADPJ in the removal of dental calculus, without causing damage to tooth surfaces.

Evaluation of smear layer and debris removal by stepwise intraoperative activation (SIA) of sodium hypochlorite

OBJECTIVES

To evaluate the efficacy of a stepwise intraoperative activation (SIA) of irrigants during and after the instrumentation compared with that of a conventional activation (CA) performed only after the instrumentation to remove smear layer and debris using different activation devices.

MATERIALS AND METHODS

A total of 70 single-rooted teeth were divided into a control group (no activation, n = 10) and two different experimental groups according to the irrigant activation protocol used: group 1 (CA), in which sodium hypochlorite was activated only after the use of the last mechanical file, and group 2 (SIA), in which activation was performed during and after the instrumentation. The two groups were divided into 3 subgroups according to the activation device used (n = 10): passive ultrasonic irrigation (PUI, subgroup a), EndoActivator (EA, subgroup b), and EDDY (subgroup c). The roots were split longitudinally and observed using scanning electron microscopy (SEM) to evaluate the presence of debris and smear layer, and the results were statistically analyzed.

RESULTS

All activation protocols and devices were more effective than control group in removing smear layer and debris from all root canal thirds (P < 0.05), except for CA-EA (group 1b) in the apical third. In the apical third, SIA was found to be more effective than CA (P < 0.05) to remove smear layer and residual debris when PUI was used, to remove the smear layer when EA was used (P < 0.05), and to remove residual debris when EDDY was used (P < 0.05). PUI and EDDY removed statistically more smear layer and debris than EA in the apical third (P < 0.05).

CONCLUSIONS

The SIA technique improved the smear layer and debris removal from the apical third and debris removal from the coronal third, and PUI and EDDY were more effective than EA in the apical third.

CLINICAL RELEVANCE

The stepwise intraoperative activation (SIA) technique may increase smear layer and debris removal.

Calculus Removal and Root Surface Roughness When Using the Er:YAG or Er,Cr:YSGG Laser Compared with Conventional Instrumentation Method: A Literature Review

Objective: The purpose of this literature review was to evaluate the effectiveness of using Er:YAG (erbium-doped yttrium/aluminum/garnet) laser or Er,Cr:YSGG (erbium, chromium-doped yttrium/scandium/gallium/garnet) laser on calculus removal and their effect on the topography and roughness of root surface in comparison with the conventional instruments in the nonsurgical periodontal therapy. Background data: One of the most challenging problems in treatment of periodontal disease is the elimination of plaque and calculus, leaving a clean and smooth root surface to decrease plaque and calculus retention, and for good gingival reattachment. Materials and methods: PubMed and Google Scholar were searched for available literature. The electronic search was limited to articles published in the period between January 2007 and April 2017, in the English language. Results: A total of 47 publications fulfilled the inclusion criteria of this systematic review and screened according to the research questions. Calculus removal using the ultrasonic instrument showed remaining calculus compared with the hand instrument, whereas, on the contrary, erbium lasers revealed no remaining calculus or smaller amounts compared with the conventional instruments when used in appropriate settings. The results of this review showed that ultrasonic instrumentation produced effects on the root surface almost similar to that of hand instrumentation. Er:YAG laser and Er,Cr:YSGG laser clarify a little more surface roughness when compared with conventional instruments. Conclusions: The present systematic review indicates that a combination of scaling and root planing (SRP) using the erbium lasers as an adjunctive therapy at certain parameters can be appropriate to remove residual debris from the root surface and at the same time have little or no negative thermal effect on the root surface. The Er:YAG laser also seems to be the most suitable for nonsurgical periodontal therapy. Additional new good-designed studies are needed to evaluate the effectiveness of erbium lasers with SRP in nonsurgical periodontal therapy.

Efficacy of sonic and ultrasonic irrigation devices in the removal of debris from canal irregularities in artificial root canals

OBJECTIVE

To evaluate the efficacy of different sonic and ultrasonic devices in the elimination of debris from canal irregularities in artificial root canals.

MATERIALS AND METHODS

A resin model of a transparent radicular canal filled with dentin debris was used. Five groups were tested, namely: Group 1 - ultrasonic insert 15.02; Group 2 - ultrasonic insert 25/25 IRRI K; Group 3 - ultrasonic insert 25/25 IRRI S; Group 4 - sonic insert 20/28 Eddy on a vibrating sonic air-scaler handpiece; Group 5 - 20.02 K-file inserted on a Safety M4 handpiece. Two different irrigants (5% sodium hypochlorite and 17% EDTA) and 3 different times of activation (20, 40, and 60 seconds) were tested. Means and standard deviations were calculated and statistically analyzed with the Kruskal-Wallis and Wilcoxon tests (p<0.05).

RESULTS

No statistically significant differences were found between the two irrigants used. Group 4 removed more debris than the other groups (p<0.05). Groups 1, 2, and 3 removed more debris than group 5 (p<0.05). A statistically significant difference (p<0.05) was found for the time of activation in all groups and at all canal levels, except between 40 and 60 seconds in group 4 at coronal and middle third level (p>0.05).

CONCLUSIONS

No significant differences were found between 5% sodium hypochlorite and 17% EDTA. When the time of activation rises, the dentin debris removal increases in all groups. Both sonic and ultrasonic activation demonstrate high capacity for dentin debris removal.

Safety concerns of Piezoelectric Units in Implantable Cardioverter Defibrillator

PURPOSE

Evidence-based research appears to conflict on the potential risk of electromagnetic interference (EMI) between piezoelectric units (Pzs) and implantable cardioverters and defibrillators (ICDs). The purpose of this study was to observe whether the EMI produced by Pzs is hazardous for ICDs.

MATERIALS AND METHODS

A cross-sectional study of 6 Pzs was conducted in vitro for EMI using an ICD system. To simulate the human body's electrical resistance, electrographic recordings were made of the ICD and lead that were immersed in a bath of saline solution. The variables investigated were the presence of EMI, the distance between the ICD and the Pz, and signal intensity, damage, and type of damage to the ICD and lead. Each series of tests was repeated 3 times, beginning with a 15-second baseline recording (control), until all recording conditions had been covered. Each Pz was recorded under the following conditions: less than 2 cm from the tip of the ICD lead; less than 2 cm from the ICD; less than 2 cm from the lead body and coils; and 15 cm from the lead or the ICD (R4).

RESULTS

In the positive control (direct contact between the lead or the ICD with the Pz switched on), the ICD detected electrical activity as false heart activity. However, after covering all test conditions, no EMI was produced by the Pzs.

CONCLUSION

No EMI or permanent changes in the functioning of the ICD were detected in vitro.

Efficacy of a new Activation Device in Irrigant Penetration Into Simulated Lateral Canals

Objective:

The aim of the present study was to compare the effects of EasyClean (EC) on irrigant delivery into simulated lateral canals using an artificial closed canal system. Passive ultrasonic irrigation (PUI) was used as a reference technique for comparison.

Methods:

Forty simulated curved root canals manufactured in transparent resin and with simulated lateral canals were instrumented with Reciproc R40 files and randomly assigned to four groups (n=10) according to the irrigant activation technique: PUI group, ECrec group (EC used in reciprocating motion), ECrot group (EC used in rotary motion), and control group (no activation performed). After activation, stereomicroscope images from each block were taken, and irrigant penetration into lateral canals was measured using Adobe Photoshop software. Data were analysed using ANOVA and Tukey’s post hoc test (α=0.05).

Results:

No penetration was observed in the control group. The ECrec group showed lower penetration than the other group (P<0.05). No differences were observed between the ECrot group and the PUI group (P>0.05).

Conclusion:

EC used in rotary motion was effective in increasing the penetration of the irrigating solution into simulated lateral canals.

Comparison of Penetration of Irrigant Activated by Traditional Methods with A Novel Technique

INTRODUCTION

The effectiveness of irrigation depends upon various irrigation activation methods & devices used.

AIM

To compare and evaluate the penetration of irrigant upto working length and into simulated lateral canals using four different irrigation activation techniques.

MATERIALS AND METHODS

The root canals of 60 single-rooted teeth were instrumented using the proTaper rotary system. After decalcification of each sample tooth, three simulated lateral canals were created at 2mm, 4mm and 6mm levels from the root apex using a 06-size C+ file. After clearing the samples they were randomly assigned into four experimental groups (n=15) and 1ml of Irrigating Contrast Solution (ICS) was delivered into all samples and then it is activated with 4 different methods Group I-Conventional syringe and needle, Group II - Sonic activation with Endo activator, Group III - Ultrasonic activation with ultrasonic tips and Group IV - Activation using reciprocation movement. All the samples were examined under a stereomicroscope and irrigant penetration was evaluated by means of penetration of ICS.

RESULTS

Group III and Group IV resulted in better penetration of ICS into lateral canals at 2mm and 4mm depth (p<0.001), when compared with Group I and II. At lateral canals 6mm all the groups except Group I, had shown 100 % penetration.

CONCLUSION

The activation of irrigant using reciprocation was able to achieve penetration of irrigating contrast solution both up to the working length and into lateral canals. Hence the clinical significance of this method of irrigant activation is that it can be used for effective penetration of irrigants both upto working length and into lateral canals.

In vitro evaluation of a novel biofilm remover

OBJECTIVE

To evaluate a novel device for its efficacy in removing experimental biofilm from root surfaces and its potential for concomitantly removing/roughening the surface substance.

METHODS AND MATERIALS

A novel acrylic rotary device (biofilm remover, BR) was tested in vitro in three experiments: surface loss, surface roughness [positive controls: Perioset (PS) and Proxoshape (PR)] and biofilm removal [positive controls: ultrasonic (US) and PS]. Surface loss/surface roughness was evaluated for dentin samples instrumented for three 20 s periods. The calcium removed during instrumentation was analysed after each interval and cumulatively, using atomic absorption spectrophotometry (AAS). Surface roughness was measured using profilometric analysis. Biofilm removal was evaluated on dentin specimens coated with a 64.5 h 6-species in vitro formed biofilm, after one 20 s treatment. Surface loss was analysed using anova with Scheffé post hoc test, and surface roughness/biofilm removal was analysed using Mann-Whitney test (all P ≤ 0.05).

RESULTS

Significantly less substance loss [μg (± 1 SD)] was observed with the novel device at all time points, both interval and cumulative (1.0 (± 0.5) versus 9.3 (± 3.2) PS and 9.9 (± 1.9) PR at 60 s). Surface roughness [μm (95% CI)] was significantly lower for BR than for PS and PR [0.00 (-0.01, 0.08) 0.20 (0.16, 0.27) and 0.21 (0.19, 0.24) at 60 s]. Significantly less biofilm bacteria remained after treatment with both BR 4.5 (-0.1, 16.2) and US 1.9 (-0.2, 14.3), compared to PS 52 (27.9, 82.1).

CONCLUSIONS

The novel biofilm remover was less damaging to dentin surfaces, while removing biofilm at least as effectively as devices used in this study.

Influence of tip wear of piezoelectric ultrasonic scalers on root surface roughness at different working parameters. A profilometric and atomic force microscopy study

Roughness on tooth surfaces is reported to facilitate the reestablishment of microbial dental plaque. Hence, the main goal of dental scaling is to remove bacterial plaque and obtain smoother tooth surfaces. This study was aimed to assess the influence of tip wear of ultrasonic scaler inserts on root surface roughness at different working parameters. Twenty piezoelectric ultrasonic scaler inserts (10 worn/10 new) were selected to examine the erosion ratio (ER) on the scaler tips and to assess the influence of tip wear on root surface roughness. Erosion on the tip surfaces was evaluated under atomic force microscopy (AFM). Root samples were prepared and instrumented by new (Group I) and worn (Group II) inserts at different working parameters. Roughness change (Rc) on root surfaces after instrumentation was examined under profilometer and compared between and within the groups. Statistically significant differences were found between the mean ERs of new and worn tips (P < 0.01). The results of this study showed that tip angulation and instrument power strongly influenced the Rc values on instrumented samples (P < 0.05). It was also revealed that tip wear influenced the Rc values on root surfaces especially at 45° tip angulation (P < 0.05). Therefore, tip wear should also be considered as much as the other parameters to minimize the surface roughness during ultrasonic treatment.