Root surface changes following manual and ultrasonic instrumentation - a scanning electron microscopic study.

OBJECTIVE: The aim of this study is to assess the efficacy of hand and ultrasonic scaling and to evaluate the surface roughness on the root surface of periodontally involved teeth using a scanning electron microscope. PATIENTS AND METHODS: A sample of 90 single-rooted teeth with a hopeless prognosis was selected for the study and divided into three separate groups. Group I consist of no treatment. In Group II, hand scaling was done using Gracey curettes, and in Group III, ultrasonic scaling was done. The teeth were then extracted and fixed in 10% formaldehyde solution for 24-48 hours and subjected to scanning electron microscopic (SEM) evaluation. RESULTS: The SEM analysis revealed that the remaining calculus index was found to be similar in the ultrasonic group and the hand scaling group, whereas the surface roughness was found to be the least in the ultrasonic group. CONCLUSIONS: Hand instrumentation has resulted in more surface roughness as compared to ultrasonic instruments.

Microcracks on the Rat Root Surface Induced by Orthodontic Force, Crack Extension Simulation, and Proteomics Study.

Root resorption is a common complication during orthodontic treatment. Microcracks occur on the root surface after an orthodontic force is applied and may be related to the root resorption caused by the orthodontic process. However, the mechanisms underlying root resorption induced by microcracks remain unclear. In this study, a rat orthodontic model was used to investigate the biological mechanisms of root resorption caused by microcracks. First, the first molar was loaded with 0.5-N orthodontic force for 7 days, and microcracks were observed on the root apex surface using a scanning electron microscope. Second, to describe the mechanical principle resulting in microcracks, a finite element model of rat orthodontics was established, which showed that a maximum stress on the root apex can cause microcrack extension. Third, after 7 days of loading in vivo, histological observation revealed that root resorption occurred in the stress concentration area and cementoclasts appeared in the resorption cavity. Finally, proteomics analysis of the root apex area, excluding the periodontal ligament, revealed that the NOX2, Aifm1, and MAPK signaling pathways were involved in the root resorption process. Microcrack extension on the root surface increases calcium ion concentrations, alters the proteins related to root resorption, and promotes cementoclast formation.

A comparative scanning electron microscopy study between the effect of an ultrasonic scaler, reciprocating handpiece, and combined approach on the root surface topography in subgingival debridement.

OBJECTIVE: This study aimed to analyze the effectiveness of root-shape inserts mounted on a reciprocating handpiece during the procedure of root surface debridement (RSD) on extracted teeth. Three different approaches were compared: ultrasonic scaling, employment of root-shape inserts mounted on a reciprocating handpiece, and a combination of both. MATERIALS AND METHODS: A total of 51 extracted teeth were divided into three groups. The first group was instrumented with an ultrasonic scaler, the second group with flexible root-shape inserts mounted on a reciprocating handpiece (grain size 40, 15, and 4 µm), whereas the final group underwent a combination of both approaches. The time required for the instrumentation was taken. The specimens were subjected to optical and scanning electron microscopy (SEM), and the photographs were evaluated by three examiners who were blinded to the study. The parameters included were: SEM roughness index (SRI) for the roughness calculation, remaining calculus Index (RCI) to evaluate the residual calculus deposits, and loss of tooth substance index (LTSI) to evaluate the loss of tooth substance caused by instrumentation. RESULT: The results revealed that the time taken for the instrumentation was on average longer when the root-shape inserts were employed alone, meanwhile the combined approach did not show significant difference in comparison with the ultrasonic scaling. The lower average RCI was obtained with a combined approach. The use of root-shape inserts seems to cause a moderate increase in LTSI, especially in a combined approach, whereas it resulted in a better average SRI. CONCLUSION: The employment of root-shape inserts seems to be effective in the RSD for its ability to obtain a smooth and calculus-free instrumented surface, especially when used in combination with an ultrasonic scaler, and their use can so represent a valid approach to be tested in further in vivo studies.

Profilometric Analysis of Periodontally Diseased Root Surfaces After Application of Different Instrumentation Tools: An In Vitro Study.

Objective: The topography of the root surface plays an important role in plaque accumulation, cell adhesion, and periodontal healing. The aim of this study is to profilometrically evaluate the root surface changes following the instrumentation using different tools. Methods: Forty dentin blocks of buccal and lingual root surfaces were obtained from 20 single-rooted periodontally diseased hopeless teeth and randomly divided into 4 groups. Each group was subjected to different root instrumentation tools such as stainless steel (SS) Gracey curette (Group 1); titanium nitride (TIN) Gracey curette (Group 2); ultrasonic piezoelectric device with a special tip designed for root surfaces (H3) (Group 3); and Er:YAG laser (Er:YAG tip) chisel (Group 4). A calibrated clinician instrumented all surfaces in each group. The root surfaces were profilometrically evaluated before and after instrumentations. Results: There were no statistical differences between the initial roughness levels of the groups. TIN curettes revealed the most prominent effect on smoothing the surface, whereas the Er:YAG tip showed the highest roughness in comparison with the other root surface instrumentation tools. Conclusions: Considering the importance of root surface roughness after treatment for the success of periodontal therapy, the TIN curette was the most periodontally appealing tool followed by H3, SS curette, and Er:YAG tip.

The effect varied scanning electron microscopy desiccation techniques has on demineralized dentin.

The study objective was to assess (a) the effect of a rubbing-application of ethylenediaminetetraacetic acid (EDTA) or citric acid (CA) has on the ultrastructure of surface dentin and (b) the effect of two scanning electron microscopy (SEM) desiccation preparation techniques have on the collagen surface produced. Treatment regions on proximal root surfaces of extracted human teeth were root planned to expose dentin. Cotton pellets soaked in either 30% CA or 24% EDTA solution were rubbed on the treatment region then processed for SEM using one of two desiccation techniques, that is, (a) critically point dried from liquid CO2 (control) or (b) air-dried from tetramethylsilane (experimental). Specimens were coated with gold/palladium and viewed/photographed with an SEM. Specimens of the control groups displayed tufted fibrils (CA > EDTA) with many dentin tubules being partially obscured by overhanging fibrils. Air-dried specimens of both treatment groups displayed a flat intact monolayer devoid of a matted meshwork of fibrous collagen. Discrete fibril "sprigs," emanating from the surface monolayer, were characteristic of the EDTA group only. The rubbing-application of EDTA on dentin produces a tufted fibril surface somewhat similar to that produced by CA. Air-drying desiccation of both resulted in marked distortion with fibril collapse/coalescence of the tufted collagen matrix.

Macrophage response and surface analysis of dental cementum after treatment with high intensity focused ultrasound.

OBJECTIVE: To investigate effects of HIFU on macrophage phenotype, surface micro-topography and nano-scale surface mechanical properties of dental cementum. MATERIALS AND METHODS: Root discs (2 mm thickness) were cut apical to CEJ and sectioned into quadrants. HIFU setup with bowl-shaped piezo ceramic transducer submerged in a water tank was used for exposure on each specimen for 15 s, 30 s or 60 s. The specimens of the control group were left without any HIFU exposure. HIFU was generated with a continuous sinusoidal wave of 120Vpp amplitude, 250 KHZ resonance-frequency and highest ultrasonic pressure of ∼10 bar at the focus. Specimens for SEM were viewed, and micro-topography characterization performed, using AFM and Ra parameter and surface area (SA) calculated by specialized SPM surface analysis software. For nano-indentation testing, experiments were carried out using AFM. Macrophage cell isolation and culturing was performed on cementum to receive the HIFU treatment at different time periods. Raman spectroscopy were scanned to create spectra perpendicular to the cementum substrate to analyze generation of standard spectra for Raman intensity ratio of hydroxyapatite normalized to the peaks ν1 960 cm-1. Data was expressed as means ± standard deviations and analyzed by one-way ANOVA in term of Ra, SA, H and Er. Different points for fluorescence intensity ratio were analyzed by Raman using Wilcoxon rank sum test. RESULTS: HIFU exposure at 60 s removed the smear layer and most of cementum appeared smoothened. AFM characterisation, showed a slight decrease in the irregularity of the surface as exposure time increased. Intact macrophages can be identified in control and all experimental HIFU groups. The level of fluorescence for the control and HIFU 15 and 30 s were low as compared to HIFU 60 s. CONCLUSION: If HIFU can be successfully implemented, it may be a possible alternative to current methods used in periodontal therapy to achieve smooth root surfaces.

Use of XRD and SEM/EDX to predict age and sex from fire-affected dental remains.

In fire scenarios, the application and accuracy of traditional odontological methods are often limited. Crystalline studies and elemental profiling have been evaluated for their applicability in determining biological profiles (age and sex) from human dentition, particularly fire- and heat-affected dental remains. Thirty-seven teeth were paired according to tooth type and donor age/sex for the analysis of crown and root surfaces pre- and post-incineration using X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDX). In unburned crowns, carbon (C) content showed a positive correlation with age, whereas phosphorus (P) and calcium (Ca) contents showed a negative correlation with age. In unburned roots, C, P and Ca contents also showed significant changes that were opposite of those observed in the crowns. In relation to sex, females exhibited a higher C ratio than males, whereas males showed significantly higher levels of oxygen (O), P and Ca in unburned roots. Incineration resulted in an increase in the crystallite size that correlated with increasing temperature. No differences in hydroxyapatite (HA) crystallite size were found between age groups; however, unburned teeth from females exhibited a larger crystallite size than did those from males. The challenges of using XRD with a 3D sample were overcome to allow analysis of whole teeth in a nondestructive manner. Further studies may be useful in helping predict the temperature of a fire.

Regenerating a monoblock to obturate root canalsvia a mineralising strategy.

To develop a novel strategy for sealing and obturating dental root canals by tooth-like tissue regeneration, premolars with mature root apices were freshly collected, and root canals were prepared by following the clinical protocols in vitro. The teeth were immersed in supersaturated calcium and phosphate solution containing gallic acid and fluoride. At certain intervals, the dental roots were taken out, and their mineral precipitates were characterised by scanning electron microscopy, energy-dispersive spectroscopy mapping, X-ray diffraction and transmission electron microscopy. The cytocompatibility of the mineralizing products were evaluated with rabbit bone-marrow-derived mesenchymal stem cells in vitro. Results showed that the precipitates were mainly composed of fluoridated hydroxyapatite with ahexagonal prism morphology. Fluoridated hydroxyapatite initially nucleated and grew from the root canal dentine surface to the root canal centre. The fluoridated hydroxyapatite precipitate and root canal dentine intergraded together such that the interface became hardly distinguishable. The fluoridated hydroxyapatite precipitate grew into and obturated the dentinal tubules. In the root canal, the regenerated fluoridated hydroxyapatite densely packed and bundled together with a c-axis extension. After 7 days of mineralisation, the root canal was completely obturated, and the apical foramen was sealed. The mineralizing products had good biocompatibility with the cells, and the cells grew well on the mineralized surface. Biomimetic mineralisation strategy provides a novel means to regenerate tooth-like tissue to seal the root canal system permanently other than by passive synthetic material filling.

Root surface alterations following manual and mechanical scaling: A comparative study.

OBJECTIVES: The aim of this study was to investigate the morphological and surface roughness changes in dental root samples following periodontal scaling by hand curette, piezoelectric ultrasonic devices or a combination of these. METHODS: Twenty-four monoradicular teeth extracted as a result of periodontal disease were divided into 4 groups: Group A was treated by piezoelectric ultrasonic scaler Piezon® Master 400; Group P by piezoelectric ultrasonic scaler PiezoSmart® ; Group C using Gracey curette 7/8; Group AC by a combined technique of piezoelectric ultrasonic scaler Piezon® Master 400 and Gracey curette 7/8. The treated samples were then analysed using a white light interferometer and scanning electron microscopy (SEM). RESULTS: Roughness analysis revealed major surface alterations in Group C (Sa  = 24.98 µm); the samples treated using the combined technique (Group AC) showed reduced but still significant alteration (Sa  = 14.48 µm), while samples treated with the piezoelectric ultrasonic devices (Group A and Group P) presented the lowest roughness values (Sa  = 8.99 and Sa  = 4.45 µm, respectively). A significant difference was found between groups C and P (P = 0.036). SEM analysis confirmed the roughness analysis revealing non-homogeneous surfaces in Group C, while a less morphological alteration was noted in the other groups. CONCLUSION: All periodontal devices used in this in vitro study produced a certain degree of surface alteration. Hand curettes appear to have a major impact on surface integrity compared with piezoelectric ultrasonic devices.

Incompatible amount of 3-D and 2-D periodontal attachments on micro-CT scanned premolars.

Micro-computed tomography (micro-CT) was employed to relate the root surface area (RSA) to the periodontal attachment levels (PALs) of extracted premolars to diagnose periodontitis. Single-rooted human maxillary and mandibular premolars 31 and 36, respectively, were surveyed by micro-CT and its associated software. RSA levels from the 1st to 10th mm, corono-apically, were analyzed using statistical t tests. The average root length (RL) and RSA of the maxillary and mandibular premolars were significantly different (p < 0.05). Both premolars demonstrated a non-significant RSA percentage comparison at the evaluated PALs. For the 30% coronal 2-D radiographic RL, the 3-D RSAs 3.77 mm and 3.99 mm apical to the cementoenamel junction (CEJ) were 39.48% and 40.65% for maxillary and mandibular premolars, respectively. At the 15% coronal 2-D RL, the 3-D RSA 2 mm apical to the CEJ of the premolars was approximately 21%. At the 50% coronal 2-D RL level, approximately 62% coronal 3-D RSA and 6.5 mm RL decreased. The amount of decrease of the RSA attachment is significant in every 2-mm measurement for both premolars. Sampling periodontal microbial pathogens based on the condition of 2-D radiographic bone and clinical attachment losses without considering 3-D RSA is potentially inadequate and may underestimate the severity of the periodontitis.

Scanning Electron Microscopy Evaluation of Root Surfaces After Instrumentation With Two Piezoelectric Devices.

Scanning electron microscopy evaluation of root surfaces after ultrasonic instrumentation was performed with 2 different metallic tips on piezoelectric devices. Fresh extracted teeth were collected for experimental observation and randomly divided into 2 groups: Test Group, where the root surfaces were treated using an iron, rough, double nano-structural coated (T-Black), corindone-treated tip, and Control Group where the root surfaces were treated with a conventional iron smooth tip. A scanning electronic microscope analysis was performed and the surface roughness and the amount of residual debris were evaluated. Descriptive and inferential statistics were performed. Twenty specimens were analyzed, 10 per group and a total of 21.4 × 10 µm has been observed. On treated area percentage of debris after ultrasonic scaling in Test Group was 1.9 ±â€Š1.8%, while in Control Group it was 5.7 ±â€Š4.3%. Within the limits of the study, it seems that the efficacy of the novel iron, rough, double nano-structural coated (T-Black), corindone-treated structure tip showed greater performance in terms of root surface debridement than the conventional iron smooth tip. The possibility to use a single tool (ultrasonic device with a specific tip) for the root planing procedure within the nonsurgical mechanical therapy may represent a significant advantage for the clinicians. The tested novel tip seems to be able to show the requested ideal characteristics. However, further clinical studies are needed to demonstrate the in vitro results.

[Root canals dentinal wall structure after photodynamic exposure]. / Izuchenie struktury stenki kornevykh kanalov zubov posle fotodinamicheskogo vozdeistviia.

The aim of the study was to assess root canal dentinal walls structure after photodynamic exposure with the use of 0.5% photoditazine. A root canal dentin of 46 single root intact teeth removed for orthodontic indications was examined by scanning electron microscope JEOL JSM-6510 (Japan). Microphotographs of the root canal wall were obtained in the orifice, central and apical parts under×2000 magnification. It was found that photoactivation of 0.5% gel photoditazine by a light source, laser or diode, with a wavelength of 635-660 nm and a power of 150-200 mW is an effective technique for removing the smear layer of the root canal wall, which facilitates the maximum opening of the dentinal tubules to a depth of 2-3 µm. The best result (the maximum number of open dentinal tubules, the absence of a smear layer) is observed with 3 min photoditazine exposure and 2 min of laser exposure. The method can be proposed as an alternative supplement to the conventional root canals irrigation.

Laser Application to the Root Surface Increases the Bonding Strength of Surface-Treated Prefabricated Glass-Fiber Posts in Teeth with Excessive Substance Loss.

BACKGROUND This study examined the effect of roughening of the root surface using an erbium-doped yttrium aluminum garnet (Er: YAG) laser on the binding strength of teeth undergoing root canal treatment. MATERIAL AND METHODS Ninety single-rooted teeth were used and assigned randomly to 9 groups (n=10 each). Root canals were prepared using the FlexMaster rotary system. An Er: YAG laser was applied to the root canals in Group 1, with no surface treatment of the glass-fiber post. In Group 2, aluminum oxide particles were applied. In Group 3, the laser was applied to the root canals, with Cojet treatment. Group 4 received laser treatment and Clearfil Ceramic Primer. In Group 5, Clearfil Ceramic Primer silane coupling was performed on post surfaces without laser treatment. In Group 6, hydrofluoric acid (HF) application was followed by Clearfil Ceramic Primer cementing of the glass post surfaces with laser application. In Group 7, HF acid treatment was performed without laser. In Group 8, the laser was applied, followed by sanding of post surfaces using Korox 50, and silane coupling with Clearfil Ceramic Primer. In Group 9, the post surfaces were sanded using Korox 50 with laser application to the root canals. The samples were subjected to a push-out experiment. The data were analyzed using Friedman's test and the Wilcoxon signed-rank test. RESULTS A significant difference in bonding strength was found among the groups (p<0.005). CONCLUSIONS Use of an Er: YAG laser in the root canal may be beneficial prior to bonding of glass posts.

Diagnóstico, planificación del tratamiento y endodoncia de un primer premolar inferior con dos canales mediante tomografía computarizada 3D: reporte de un caso

El tratamiento endodóntico debe considerar que los dientes presentan una morfología del sistema de canales radiculares con alta variabilidad y complejidad. por lo tanto, el conocimiento acabado de la anatomía radicular y la planificación del procedimiento utilizando sistemas imagenológicos previos a la realización del tratamiento endodóntico, como la tomografía computarizada 3D (CBTC), mejoran el pronóstico, aumentando las probabilidades de éxito. el objetivo de este reporte es mostrar la secuencia de una resolución clínica de un primer premolar inferior (diente 4.4) con una anatomía compleja, utilizando el CBTC tanto en el diagnóstico como en la planificación.

Preservation of root cementum: a comparative evaluation of power-driven versus hand instruments.

OBJECTIVES: The purpose of this study was to evaluate the effects of three distinct periodontal treatment methods in comparison with hand instrumentation on residual cementum of periodontal diseased teeth. Cementum can influence the activities of periodontal cells and may play an important regulatory role in periodontal treatment. The ideal method for periodontal therapy involves removal of biofilm, calculus and endotoxin while preserving root cementum. MATERIAL AND METHODS: Forty-eight caries free, single-rooted teeth in patients diagnosed with severe chronic periodontitis were treated using four different methods prior to extraction. The teeth were instrumented subgingivally at one approximal site either by hand curettes (HC), piezoelectric ultrasonic scalers (U), piezoelectric ultrasonic scalers following air polishing (U + AP) or air polishing (AP) alone. Following extraction of teeth, instrumented and non-instrumented sites were analysed with a dissecting microscope and SEM for measurement of the amount of and surface characteristics of residual cementum. RESULTS: The percentage of coronal cementum remaining following subgingival instrumentation was 84% for U, 80% for U + AP, 94% for AP and 65% for HC. Although subgingival instrumentation of apical portions of the cementum demonstrated 6% less retained cementum in comparison with coronal portions, the amount of retained cementum with AP was still significantly greater than with HC. SEM results found the smoothest root surfaces were produced by the HC followed by the AP, while root surfaces instrumented by U or U + AP presented grooves and scratches. CONCLUSIONS: This study demonstrated that AP was superior to U devices in preserving cementum, whereas HC were the most effective instruments in removing cementum.

Late Dental Implant Failures Associated with Retained Root Fragments: Case Reports with Histologic and SEM Analysis.

Interest has recently developed in the purposeful retention of root fragments with their periodontal apparatus to support bone and soft tissue at immediate implant sites in the esthetic zone. This methodology is designed to avoid bone grafting, connective tissue grafts, and the use of membranes and may have short-term benefits in terms of tissue preservation. However, it is not completely without long-term risks. At times, implants may be unintentionally placed into edentulous sites where root fragments remain. This report presents two cases of long-term failure postloading associated with unintentionally retained root fragments. Histologic evaluation evidenced retained root fragments in close association with dental implants and the surrounding bone. Scanning electron microscopic evaluation revealed that the failed implant surfaces were infiltrated by bacterial deposits and calculus. Clinicians should exercise caution when placing dental implants in sites with retained root fragments, as long-term risks may be associated with this therapy.

FTIR and SEM analysis applied in tissue engineering for root recovering surgery.

Gingival recession is defined by the displacement of the gingival margin in the apical direction, which overcomes the cementum enamel junction. The etiology of gingival retraction is related to tissue inflammation caused by the accumulation of biofilm, by trauma from brushing action. Aesthetic periodontal surgery aims to return the root coverage to aesthetic harmony, and reduce the risk of periodontal disease and caries. To assist in the root coverage process, the porcine collagen matrix (PCM) has been widely studied. The objectives of this study are to identify the types of collagen that make up the PCM and analyze their morphology. For this, five PCM fragments, 2 mm (thickness) × 2.6 mm (width), were analyzed with the aid of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The analysis by SEM showed that the PCM consists of two layers; the surface layer is compact, low porosity, and smooth surface, and a foamed underlying layer has high porosity. Through FTIR we identified that the surface and underlying layers are composed of collagen types I and III, respectively. This biomaterial is conducive to root coverage; it allows adsorption and cell proliferation following the matrix resorption and periodontal tissue neoformation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1326-1329, 2017.

Morphology and age-related changes in calcospherites of human teeth: an ultrastructural study.

BACKGROUND: Dentine has been examined extensively for age-related physiological changes, but there are limited data on age-related changes at ultrastructural level of dentine. AIM: The present study aimed to examine age-related ultrastructural changes in calcospherites of human dentine under the scanning electron microscope. MATERIALS AND METHODS: Thirty single rooted teeth of North Western adult Indians (18-75 years) were collected from the Department of Oral Health Sciences, PGIMER, Chandigarh. Labiolingual sections were prepared and morphology of calcospherites was studied at different locations (coronal, cervical, midroot and apical) of the tooth. RESULTS: Morphologically, four types (I [small, unfused and discrete], II [partially fused and globular], III [large, completely fused] and IV [structureless]) of calcospherites were seen in the sample. With advancing age, type I calcospherites approached neighbouring crystals and changed their form to type II, which ultimately coalesced and transformed to type III. Results revealed that among different age groups (young, middle and old), calcospherites of only type I, II and III showed statistically significant differences in their shapes using Pearson's Chi-square test. Statistically non-significant differences were obtained in the shapes at different locations of the tooth. CONCLUSIONS: Results showed that calcospherites get fused as age advances. There is a change in the shape of calcospherites based on the location of the tooth.

Evaluation of Root Canal Dentin Erosion after Different Irrigation Methods Using Energy-dispersive X-ray Spectroscopy.

INTRODUCTION: The purpose of this study was to examine the level of erosion in root dentin caused by different irrigation methods and protocols. METHODS: Thirty-five extracted upper molar teeth were instrumented and divided into 7 groups to undergo treatment by different methods: negative control, GentleWave System (Sonendo Inc, Laguna Hills, CA), and syringe needle irrigation following different protocols. The teeth were instrumented to size #25/.08 or #30/.09 for needle irrigation groups and to ProTaper size S1 for the GentleWave group under 5% sodium hypochlorite (NaOCl). The needle irrigation groups were subjected to final rinses of 2 minutes of 3% NaOCl + 2 minutes of 8% EDTA (3% N2 + 8% E2), 2 minutes of 3% NaOCl + 2 minutes of 8% EDTA + 1 minute of 3% NaOCl (3% N2 + 8% E2 + 3% N1), 2 minutes of 5% NaOCl + 2 minutes of 17% EDTA (5% N2 + 17% E2), 2 minutes of 5% NaOCl + 2 minutes of 17% EDTA + 1 minute of 5% NaOCl (5% N2 + 17% E2 + 5% N1), and 5 minutes of 5% NaOCl + 5 minutes of 17% EDTA + 5 minutes of 5% NaOCl (5% N5 + 17% E5 + 5% N5), respectively. The root canal surface was observed by scanning electron microscopy, and the dentin composition was analyzed by continuous line scanning for 300 µm into dentin using energy-dispersive X-ray spectroscopy. RESULTS: A slight but statistically significant decrease of calcium and an increase of carbon was measured in the 5% N2 + 17% E2 group in comparison with the control; no significant difference was found among GentleWave, 3% N2 + 8% E2, and 5% N2 + 17% E2 (P > .05). A final 1-minute rinse with 3% or 5% NaOCl reduced calcium and phosphorus to a significantly lower level than in groups without a 1-minute final rinse (P < .05). Final irrigation with 5% NaOCl for 5 minutes removed almost all calcium and phosphorus. Scanning electron microscopy showed canal wall erosion when an additional final irrigation with NaOCl was done. CONCLUSIONS: NaOCl followed by final EDTA irrigation performed either by syringe needle or the GentleWave System caused minimal dentin erosion. Erosion was measured as increased loss of calcium and phosphorus in samples in which additional final irrigation was performed using NaOCl after EDTA.

Microscopic view of scaling influence on the root, using different power and time settings.

OBJECTIVE: The aim of this paper was to identify the appropriate power setting and operation time required to achieve optimal efficiency in calculus debridement while preventing excessive cementum loss. METHOD AND MATERIALS: The study included 30 extracted molars with heavy deposits of calculus, visible to the the naked eye. Experimental areas (3 × 4 mm) were delineated below the cementoenamel junction. The teeth were cut cross-sectionally and randomly allocated into three groups: low, medium, and high power settings. A magnetostrictive ultrasonic scaler with Dentsply slimline plain insert was used with light force at 0-degree tip angulation for a 10 second interval. Before and after treatment, the samples were visualized using digital stereo microscopy at 100× magnification. RESULTS: Mean time required for dental calculus removal was 70, 50, and 30 seconds for low, medium, and high power settings, respectively. Root calculus removal rates for low, medium, and high power settings were 4.5, 6.7, and 8.2 µm/s, respectively (P = .0045, P < .01). Mean time required for dental cementum removal was 30, 30, and 20 seconds for low, medium, and high power settings, respectively. Cementum removal rates for low, medium, and high power settings were 1.7, 2.2, and 3.3 µm/s, respectively (P = .0127, P < .05). CONCLUSION: The most efficient dental calculus removal occurred within the first 30 seconds using a high power setting with light force at 0-degree tip angulation, which was recommended for roots with heavy calculus. Later on, to minimize cementum loss, the low power setting should be used for less than 30 seconds to balance between rapid calculus removal and a potential risk of cementum loss resulting in dental sensitivity. Ultrasonic scaling using the high power setting in the first 30 seconds, followed by continuous scaling for less than 30 seconds, using the low power setting, is recommended for roots with heavy calculus.