An in vitro comparative study of a reciprocating scaler for root surface debridement

Micro-CT evaluation of the effect of various ScRp instrumentation methods on cement loss, porosity and micro-crack formation

OBJECTIVES

The purpose of this study was to compare the effectiveness of three different instruments on cement loss, porosity and micro-crack formation, which was not evaluated before, following scaling and root planning (SRP) using micro-computed tomography (micro-CT).

METHODS

In this experimental study, 30 single-rooted extracted human teeth were used and divided into three groups. All the teeth were scanned with micro-CT before and after SRP. Group 1: SRP was performed with Gracey curettes, Group 2: SRP was performed by using an ultrasonic device, and Group 3: SRP was performed by using diamond burs. Cement loss from the root surface, porosity, and micro-crack formation in the root dentine were analysed. Micro-CT is used for qualitative and quantitative analysis of samples. The obtained data were analysed statistically (p < 0.05).

RESULTS

Minimum cement loss following SRP was detected with ultrasonic scaler (26.98 mm3), whereas the highest was created by diamond burs (96.20 mm3) (p < 0.05). The total porosity values after SRP were 0.278%, 0.334% and 0.252% for Groups 1, 2 and 3, respectively. Although Group 3 had the least porosity values, there was no statistically significant difference between the groups. The highest micro-crack formation was seen in Group 2 and the lowest was in Group 1 with a significant difference (p < 0.05).

CONCLUSIONS

More cement loss was observed with diamond burs. Ultrasonic devices appear to be a viable alternative to instrumentation with curettes. However, ultrasonic devices should be used carefully because of micro-crack formation since the micro-crack resulting from instrumentation with hand instruments is the least of all.

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.

Clinical and Immunological Effects of Er,Cr:YSGG Laser in Nonsurgical Periodontal Treatment: A Randomized Clinical Trial

Objective: The aim of this study was to compare the clinical and immunological results of nonsurgical periodontal treatment with or without the erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser. Background data: As lasers have begun to be used in dentistry, the Er,Cr:YSGG laser has started to attract attention in the field of periodontology. Materials and methods: Fifty-nine nonsmoking patients with advanced chronic periodontitis were randomly allocated to a test group (full-mouth ultrasonic supra- and subgingival debridement+Er,Cr:YSGG laser application) and a control group (full-mouth ultrasonic supra- and subgingival debridement+root planing with Gracey curettes). The laser parameters were set as follows: 1.5 W output power, pulse mode H (pulse duration of 140 μs), pulse frequency of 20 Hz, and an air-water spray ratio of 10% air and 15% water. The instrumentation was performed until the operator felt that the root surfaces were adequately debrided. Probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), plaque index, interleukin-1 beta (IL-1β), matrix metalloproteinase-8 (MMP-8), tissue inhibitor metalloproteinase-1 (TIMP-1), and MMP-8/TIMP-1 levels in gingival crevicular fluid were evaluated at baseline, 6 weeks, and 3 months postoperatively. Results: There were statistically significant differences in PD, which was our primary outcome, and BOP between the groups at both examinations [p < 0.001 and p < 0.001 (for PD) and p = 0.048 and p < 0.001 (for BOP), respectively], in favor of the laser group. However, there were no significant differences among groups at any time for CAL gain (p = 563 and p = 369, respectively). No significant differences in MMP-8, TIMP-1, and MMP-8/TIMP-1 levels were detected among groups. There was a statistically significant difference for IL-1β levels among groups at 3-month evaluations in favor of the laser group. Conclusions: Using the Er,Cr:YSGG laser instead of hand instruments in nonsurgical periodontal treatment has shown additional improvements in terms of pocket reduction and gingival bleeding compared with traditional nonsurgical therapy.

Removal of simulated biofilm: an evaluation of the effect on root surfaces roughness after scaling

BACKGROUND

Despite the development of less invasive devices, a debate exists about the benefits and risks of hand versus powered root surface instrumentation used in supportive periodontal therapy (SPT). The aim of the in vitro study was to differentially compare plaque removal efficacy and root surface roughening of newly developed sonic, ultrasonic scaler, and curettes in the hands of experienced versus less experienced operators.

MATERIALS AND METHODS

Sonic (AIR), ultrasonic devices (TIG), and double-gracey curettes (GRA) were utilized by seven experienced (EO) and four less experienced operators (LO) for root surface instrumentation of standardized plastic teeth on manikins' heads in a randomized sequence. The proportion of residual simulated plaque (RSP area in %) was planimetrically assessed, and the average root surface roughness produced (Ra and ∆Ra in μm) was measured by a precision profilometer.

RESULTS

The uninstrumented root surfaces showed a Ra of (median (Q25/Q75)) 1.00 μm (0.83/1.16). Following instrumentation, EO left significantly less RSP than LO regardless of the used instruments (20.00 % (10.00/34.00) vs. 26.00 % (12.00/44.00) p < 0.001), whereas the ∆Ra values (0.29 μm (-0.04/0.96) vs. 0.35 μm (-0.04/1.01), p = 0.237) failed to show significant differences. The surface roughness was higher with GRA followed by AIR then TIG regardless of operators' experience (p < 0.001).

CONCLUSION

Within the limits of the present study, the sonic device was most efficient in plaque removal, while the ultrasonic device produced the least surface roughness.

CLINICAL RELEVANCE

All three tested instruments seem effective in the mechanical root debridement during SPT, whereat the ultrasonic device show the smoothest root surface of all.

A comparative evaluation of the efficacy of manual, magnetostrictive and piezoelectric ultrasonic instruments--an in vitro profilometric and SEM study

Objectives

The debridement of diseased root surface is usually performed by mechanical scaling and root planing using manual and power driven instruments. Many new designs in ultrasonic powered scaling tips have been developed. However, their effectiveness as compared to manual curettes has always been debatable. Thus, the objective of this in vitro study was to comparatively evaluate the efficacy of manual, magnetostrictive and piezoelectric ultrasonic instrumentation on periodontally involved extracted teeth using profilometer and scanning electron microscope (SEM).

Material and Methods

30 periodontally involved extracted human teeth were divided into 3 groups. The teeth were instrumented with hand and ultrasonic instruments resembling clinical application. In Group A all teeth were scaled with a new universal hand curette (Hu Friedy Gracey After Five Vision curette; Hu Friedy, Chicago, USA). In Group B Cavitron^TM FSI - SLI^TM ultrasonic device with focused spray slimline inserts (Dentsply International Inc., York, PA, USA) were used. In Group C teeth were scaled with an EMS piezoelectric ultrasonic device with prototype modified PS inserts. The surfaces were analyzed by a Precision profilometer to measure the surface roughness (Ra value in µm) consecutively before and after the instrumentation. The samples were examined under SEM at magnifications ranging from 17x to 300x and 600x.

Results

The mean Ra values (µm) before and after instrumentation in all the three groups A, B and C were tabulated. After statistically analyzing the data, no significant difference was observed in the three experimental groups. Though there was a decrease in the percentage reduction of Ra values consecutively from group A to C.

Conclusion

Within the limits of the present study, given that the manual, magnetostrictive and piezoelectric ultrasonic instruments produce the same surface roughness, it can be concluded that their efficacy for creating a biologically compatible surface of periodontally diseased teeth is similar.

Efficiency of the VectorTM-system compared with conventional subgingival debridement in vitro and in vivo

OBJECTIVE

To assess the efficacy of the novel ultrasonic Vector -system system for subgingival debridement and to compare the results with conventional periodontal instrumentation in vitro and in vivo.

MATERIAL AND METHODS

Forty extracted human teeth were treated in vitro: Vector -system with polishing (VP) and abrasive fluid (VA), conventional ultrasonic system (U) and hand instrument (H). At intervals of 40 s, calculus removal was assessed using a 3D laser scanning device. Eight single-rooted teeth were treated in vivo with the Vector -system or hand instruments. Subgingival plaque samples were obtained for microbiological evaluation. After extraction, residual calculus was assessed by means of digitized planimetry.

RESULTS

In vitro efficiency of hand instruments was statistically higher compared with the conventional ultrasonic system (p < 0.05) and the Vector -system with no difference between U and VA (p > 0.05) and VA and VP (p > 0.05). Residual calculus following in vivo instrumentation was not different in the Vector and the hand instrument group (p > 0.05) but treatment time with the Vector -system was statistically higher (p < 0.05). A similar reduction of periopathogenic bacteria could be observed in both groups.

CONCLUSION

Using the Vector -system, root surfaces can be debrided as thoroughly as with conventional instruments. However, treatment is more time consuming than conventional debridement.

Efficiency of subgingival calculus removal with the Vectortm-system compared to ultrasonic scaling and hand instrumentation in vitro

OBJECTIVE

The recently introduced Vector-system (Duerr Dental, Bietigheim-Bissingen, Germany) is recommended to be used in conjunction with different insert tips and irrigation fluids. The aim of the study was to assess subgingival calculus removal depending on the mode of operation and to compare the results to conventional methods for root debridement.

METHODS

Sixty extracted human teeth with calculus on the root surface were treated in an artificial periodontal pocket model using six methods: Vector-system with metal probe insert (VPP) or metal curette insert (VPC), both used with polishing fluid, Vector-system with metal probe insert (VAP) or metal curette insert (VAC), both used with abrasive fluid, EMS-ultrasonic system (U) and hand instrument (Gracey curette). Photographs of the root surface were taken at intervals of 10 s and calculus removal was assessed using a surface analysis software until the root surfaces were cleaned completely. Analysis of variances (ANOVA) of the ranks with subsequent comparison of mean ranks and calculation of homogeneous groups (Scheffe) were used for statistical analysis.

RESULTS

Employing the hand instrument, highest efficiency could be observed (0.340 mm2/s). Calculus removal with the Vector-system and metal probe insert (VPP: 0.036 mm2/s; VAP: 0.067 mm2/s) was less effective (p < 0.05) than using the system with metal curette inserts (VPC: 0.122 mm2/s; VAC: 0.209 mm2/s). Employing the abrasive fluid, removal of deposits with the metal curette insert was as efficient as with the conventional ultrasonic system (U: 0.199 mm2/s, p > 0.05).

CONCLUSION

The present in vitro study indicates that the efficiency of calculus removal with the Vector-system is significantly dependent on the selection of inserts and irrigation fluids.

Local Anti-Infective Therapy: Mechanical and Physical Approaches. A Systematic Review

BACKGROUND

Although mechanical non-surgical therapy (scaling and root planing) is the most common means of initial treatment of periodontal diseases, the relative clinical efficacy of various methods, including manual versus machine-driven, with or without adjunctive agents, has not been determined.

RATIONALE

This systematic review analyzes the literature in an effort to identify the most effective therapies, based on both clinical and patient-centered outcomes.

FOCUSED QUESTION

In patients with periodontitis, what is the effect of mechanically-driven instrumentation (e.g., power-driven) and/or subgingival irrigation with and without manual instrumentation compared to manual instrumentation alone?

SEARCH PROTOCOL

Two investigators examined MEDLINE and the Cochrane Oral Health Group specialized registry for clinical trials published in English. Hand searches were performed of the International Journal of Periodontics & Restorative Dentistry, Journal of Clinical Periodontology, Journal of Periodontology, and Journal of Periodontal Research. Searches were performed for articles published through April 2002. Editors of these journals were asked to provide information on articles currently under review. In addition, an electronic discussion group on periodontal diseases and treatment was contacted, as were manufacturers of manual and mechanical instruments and of adjunctive agents.

SELECTION CRITERIA

INCLUSION CRITERIA

Only randomized clinical trials, cohort studies, or case-control studies at least 3 months long were included. All studies had to compare manual instrumentation (MI; scaling and root planing [SRP]) alone with some other form of non-surgical therapy. These included MI versus mechanically-driven instruments (MDI) alone; MI versus MI plus MDI; MI versus MDI plus an agent (e.g., chlorhexidine); and MI versus subgingival irrigation (SGI) delivered in conjunction with MI or MDI.

EXCLUSION CRITERIA

Studies not meeting the inclusion criteria or those treating periodontal diseases as a manifestation or complication of some other disease or disorder were not included.

DATA COLLECTION AND ANALYSIS

Probing depth, clinical attachment level, bleeding on probing, and gingival recession were the primary outcomes. Because of the heterogeneity of the patient populations, treatments, and outcome measures, meta-analysis was not appropriate. Only in-study data were compared. Four of the studies required extrapolating data from figures and graphs, resulting in questionable accuracy.

MAIN RESULTS

1. Nine studies, representing a study population of 129, were included in the review. 2. Five studies compared MI with MDI alone. The other 4 compared MI alone to MI plus SGI or subgingival tissue treatment. 3. There was comparable efficacy between MI and MDI when treating single-rooted teeth. 4. The use of SGI or subgingival tissue treatment as an adjunct to MI provided no additional benefit compared to MI alone. 5. Findings reported in the review must be interpreted with considerable caution, as lack of study heterogeneity made meta-analysis unfeasible and the need to extrapolate outcomes values from graphs and figures may have resulted in some inaccuracy.

REVIEWERS' CONCLUSIONS

1. Manual and mechanically-driven instrumentation appears comparable in affecting improved clinical outcomes. 2. Instrumentation time for MI and MDI were similar, except for 1 study in which MDI was significantly shorter. 3. Adjunctive SGI plus MI and subgingival tissue treatment result in similar clinical outcomes when compared to MI alone. 4. If study data are to be effectively and analytically combined to facilitate meaningful comparisons of treatment outcomes, detailed and standardized study designs must be developed and used consistently in clinical trials.

Ultrasonic dental scaler: associated hazards

BACKGROUND

The ultrasonic dental scaler is a valuable tool in the prevention of periodontal disease; however, this equipment has a number of hazards with which it is associated. These include heating of the tooth during scaling, vibrational hazards causing cell disruption, possible platelet damage by cavitation, associated electromagnetic fields that can interrupt pacemakers, auditory damage to patient and clinician and the release of aerosols containing dangerous bacteria.

OBJECTIVE

To collate the research reported on the various hazards associated with the ultrasonic dental scaler and discuss possible future research areas.

DATA SOURCES

The scientific literature was searched using Web of Science, EMBASE and Medline, and the results of these were then hand-searched to eliminate nonrelevant papers.

CONCLUSIONS

This review outlines some of the research conducted into these areas of associated hazard in order to assess their significance in the clinical situation, and discusses ideas for future research. Suggestions of recommendations are given, which have been previously investigated for their aid in reducing possible hazards, to ensure the safe working of ultrasonic scalers in the dental practice.

Clinical evaluation of an Er:YAG laser combined with scaling and root planing for non-surgical periodontal treatment. A controlled, prospective clinical study

OBJECTIVES

The purpose of the present controlled clinical trial was to compare the treatment of advanced periodontal disease with a combination of an Er:YAG laser (KEY II, KaVo, Germany) and scaling and root planing with hand instruments (SRP) to laser alone.

MATERIAL AND METHODS

Twenty healthy patients with moderate to advanced periodontal destruction were randomly treated in a split-mouth design with a combination of an Er:YAG laser and SRP (test) or with laser (control) alone. The used energy setting for laser treatment was 160 mJ/pulse at a repetition rate of 10 Hz. Prior to treatment and 3, 6 and 12 months later the following parameters were evaluated by a blinded examiner: Plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR) and clinical attachment level (CAL). Subgingival plaque samples were taken at each appointment and analysed using darkfield microscopy for the presence of cocci,-non-motile rods, motile rods and spirochetes. No statistical significant differences in any of the investigated parameters between both groups were observed at baseline.

RESULTS

Initially, the plaque index was 1.0 +/- 0.6 in both groups. At the 3-month examination the plaque scores were markedly reduced and remained low throughout the study. A significant reduction of the GI and BOP occurred in both groups after 3, 6 and 12 months (P < 0.05, P < 0.05, respectively). The mean PD decreased in the test group from 5.2 +/- 0.8 mm at baseline to 3.2 +/- 0.8 mm after 12 months (P < 0.05) and in the control group from 5.0 +/- 0.7 mm at baseline to 3.3 +/- 0.7 mm after 12 months (P < 0.05). The mean CAL decreased in the test group from 6.9 +/- 1.0 mm at baseline to 5.3 +/- 1.0 mm after 12 months (P < 0.05) and in the control group from 6.6 +/- 1.1 mm at baseline to 5.0 +/- 0.7 after 12 months (P < 0.05). Both groups showed a significant increase of cocci and-non-motile rods and a decrease in the amount of motile rods and spirochetes.

CONCLUSION

In conclusion, the present results have indicated that: (i) non-surgical periodontal therapy with both an Er:YAG laser + SRP and an Er:YAG laser alone may lead to significant improvements in all clinical parameters investigated, and (ii) the combined treatment Er:YAG laser + SRP did not seem to additionally improve the outcome of the therapy compared to Er:YAG laser alone.

Antimicrobial effects of 2.94 microm Er:YAG laser radiation on root surfaces: an in vitro study

OBJECTIVES

This in vitro study investigated the antimicrobial effects of 2.94 microm Er:YAG laser radiation on root surfaces.

MATERIALS AND METHODS

The study used 125 extracted teeth which were divided into 2 groups (A, B) of 40 teeth and 3 groups of 15 teeth (C, D, E). A defined and similarly-sized area of the root surface was inoculated with an aliquot of 7 microl of a bacterial suspension of Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Actinobacillus actinomycetemcomitans (ATCC 43719), Eikenella corrodens (ATCC 51724), or Peptostreptococcus micros (ATCC 33270). Subsequently, the samples from each group were further divided into subgroups which have been irradiated either with 55, 75, and 105 (group A, B) or 55 and 75 (group C, D, E) laser pulses. 1 subgroup of each group was left untreated as control. The source of laser radiation was an Er:YAG laser emitting pulsed infrared radiation at a wavelength of 2.94 microm. The number of bacteria was determined using the surface spread plate technique. The statistical analysis was performed using ANOVA followed by the Scheffé-test.

RESULTS

Depending on the number of laser pulses the bacterial load in the E. coli group was reduced by the Er:YAG laser radiation after exposure to 105 laser pulses to 5.5% of the initial count and that in the Staph. aureus group to 15.1%. The number of bacteria in case of A. actinomytemcomitans was reduced to 8.3%, in case of E. corrodens to 3.0% and in case of P. micros to 22.0% after application of 75 laser pulses.

CONCLUSION

Besides the selective removal of plaque and calculus, the 2.94 microm Er:YAG laser radiation causes reduction in bacteria on root surfaces.

Subgingival polishing with a teflon-coated sonic scaler insert in comparison to conventional instruments as assessed on extracted teeth (II). Subgingival roughness

AIM

To assess the root surface roughness and topography on extracted teeth using different instruments.

MATERIAL AND METHODS

In the present study, laser profilometry was used to examine the 3-D roughness values Ra and Rz and topography of root surfaces of periodontally-involved teeth instrumented in vivo with curette, conventional ultrasonic device, conventional or teflon-coated sonic scaler insert, or the Periotor instrument (12 teeth per instrument type), and compare these with uninstrumented cementum surfaces.

RESULTS

The roughness values Ra and Rz of the roots treated with the different instruments showed a similar pattern: curettes and the Periotor instrument produced the smoothest surfaces (Ra about 1.5 microm, Rz 30 microm); the 4 other instruments created similar Ra values of approximately 2-3 microm and Rz roughness of about 50-70 microm, which equals the untreated root surface. For Ra, the difference between the curette or the Periotor instrument and the teflon-coated sonic insert or ultrasonic insert was significant, and for Rz, a significant difference was found between the curette or the Periotor instrument and ultrasonic insert. As opposed to surfaces debrided with the Periotor and teflon-coated sonic scaler, it appears that hand instruments markedly reconfigure surfaces.

CONCLUSION

The lowest root-surface roughness values were obtained with hand instruments. The teflon tubing on the sonic scaler insert effected no change of topography or roughness as compared to uninstrumented, control surfaces. However, it must be pointed out that hard-tissue removal was not investigated.

A comparative in vitro study of a magnetostrictive and a piezoelectric ultrasonic scaling instrument

BACKGROUND

The effects of magnetostrictive ultrasonic instruments and piezoelectric ultrasonic instruments on tooth surfaces seem to differ with regards to root debridement.

AIM

The purpose of this study was to compare a magnetostrictive ultrasonic scaling instrument with a piezoelectric ultrasonic scaling instrument and a hand curette regarding time taken, calculus removal, tooth surface roughness (Ra), and SEM examination before and after instrumentation.

METHODS

30 extracted human teeth with subgingival calculus were assigned to one of three treatment groups (n=10). The working force was standardised for both ultrasonic instruments at 200 g and for the curette at 500 g.

RESULTS

The results revealed that the time needed for instrumentation was 126.1+/-38.2 s for the curette, significantly more than for the piezoelectric ultrasonic instrument (74.1+/-27.6 s; p<0.05) and 104.9+/-25.4 s for the magnetostrictive ultrasonic instrument. Remaining calculus was similar for all three groups. The end Ra values were significantly worse for the piezoelectric instrument (2.02+/-0.41; p<0.05) compared to 1.42+/-0.48 for the curette and 1.36+/-0.41 for the magnetostrictive instrument. The SEM examination revealed the smoothest surfaces but, subjectively, the most tooth substance loss after the curette, followed by the magnetostrictive instrument, with the least substance loss, and then the piezoelectric instrument, with medium substance loss.

CONCLUSION

The piezoelectric ultrasonic scaler was more efficient than the magnetostrictive ultrasonic scaler in removing calculus but left the instrumented tooth surface rougher.

The effect of working tip angulation on root substance removal using Er:YAG laser radiation: an in vitro study

OBJECTIVES

The present investigation attempted to determine the amount of cementum and/or dentin removal with Er:YAG laser radiation, dependent on the angulation of a specially-developed application tip.

MATERIAL AND METHODS

Subject of the study were 150 extracted incisors, canines, premolars, and molars. Source of laser radiation was an Er:YAG laser device emitting pulsed infrared radiation at a wavelength of 2.94 microm with a pulse duration of 250 micros and a pulse repetition rate of 10 pps. The samples of the 3 study groups were irradiated with 380 laser pulses at radiation energies of 60 mJ (group A), 100 mJ (group B), or 180 mJ (group C). In each group, 10 samples were treated at working tip angulations of 15 degrees , 30 degrees , 45 degrees , 60 degrees , and 90 degrees. The substance removal was determined 3-dimensionally using a newly developed laser scanning system (100,000 surface points per sample, accuracy 5 microm) and a special image-analysing software (Match 3D). Statistical analysis was completed with ANOVA followed by multiple comparisons using the Scheffé-test and with linear regression analysis according to Pearson-Bravais (p < 0.05).

RESULTS

Strong dependence of substance removal, both determined as maximum depth of the defects (0.5% quantil) as well as defect volume, on the angulation of the working tip was shown. At 60 mJ, the depth of the defects was 41.39 (+/- 32.55) microm at an angulation of 15 degrees and that at 90 degrees was 181.39 (+/- 74.42) microm (R2= 0.921). For the radiation energy at 100 mJ, the depth of the defects ranged from 51.96 (+/- 26.86) microm at 15 degrees to 306.64 (+/- 62.44) microm at 90 degrees (R2 = 0.983). Choosing radiation energies at 180 mJ, the depth of the defects ranged from 64.73 (+/- 27.73) microm at 15 degrees to 639.89 (+/- 47.28) microm at 90 degrees , on average (R2 = 0.853).

CONCLUSIONS

The results of the present study provide clear evidence that besides the physical radiation parameters, also the parameters of clinical handling, in particular the angulation of the application tip, has a strong influence on the amount of root substance removal using Er:YAG laser radiation.

Root substance removal with Er:YAG laser radiation at different parameters using a new delivery system

BACKGROUND

The recently introduced Er:YAG laser radiation appears to be a promising alternative in treating dental hard tissue due to its thermo-mechanical ablation properties and the lack of thermal side effects. The present in vitro study attempted to evaluate the use of Er:YAG laser radiation in combination with a specially developed delivery system in removing calculus from root surfaces.

METHODS

Fifty extracted anterior teeth, premolars and molars, were divided into 2 groups of 25 each with (group A) and without (group B) subgingival calculus. Source of radiation was an Er:YAG laser device with a wavelength of 2.94 microm, in the infrared optical spectrum, a pulse duration of 250 ns, and a pulse repetition rate of 15 pps. In each group, 6 teeth were irradiated with 300 laser pulses either at 60 mJ, 80 mJ, 100 mJ, or 150 mJ. The samples were continually moved linearly using a computer numeric controlled device. The volumetric evaluation of root substance removal was performed with a 3-dimensional laser scanning system (100,000 surface points per sample, accuracy: 5 microm) and special image analyzing software. A scanning electron microscopic (SEM) observation was performed to assess the laser induced ultrastructural changes on the root surfaces. Statistical analysis was carried out with ANOVA followed by the Scheff*e test and with regression analysis according to Pearson-Bravais at a level of significance of 5% (P <0.05).

RESULTS

The linear measurement of substance removal on calculus samples (group A) revealed average depths between 174.38 (+/-16.13) microm and 501.85 (+/-111.01) microm. Defect depths on the teeth without calculus (group B) ranged from 37.78 (+/-14.03) microm to 484.44 (+/-80.63) microm. The SEM observation of laser-treated root surfaces revealed no signs of thermal damage; e.g., melting, fusion, or cracking.

CONCLUSIONS

The results of the present study showed that a substance removal with Er:YAG laser radiation at lower energy densities is comparable, in effect, to that after conventional root surface instrumentation with curets. The results seem to indicate that calculus removal can be selectively done using lower radiation energies. Considering the favorable results of the SEM investigation, the use of the Er:YAG laser in periodontal therapy may be possible in the future.

Dental calculus: recent insights into occurrence, formation, prevention, removal and oral health effects of supragingival and subgingival deposits

Dental calculus, both supra- and subgingival occurs in the majority of adults worldwide. Dental calculus is calcified dental plaque, composed primarily of calcium phosphate mineral salts deposited between and within remnants of formerly viable microorganisms. A viable dental plaque covers mineralized calculus deposits. Levels of calculus and location of formation are population specific and are affected by oral hygiene habits, access to professional care, diet, age, ethnic origin, time since last dental cleaning, systemic disease and the use of prescription medications. In populations that practice regular oral hygiene and with access to regular professional care, supragingival dental calculus formation is restricted to tooth surfaces adjacent to the salivary ducts. Levels of supragingival calculus in these populations is minor and the calculus has little if any impact on oral-health. Subgingival calculus formation in these populations occurs coincident with periodontal disease (although the calculus itself appears to have little impact on attachment loss), the latter being correlated with dental plaque. In populations that do not practice regular hygiene and that do not have access to professional care, supragingival calculus occurs throughout the dentition and the extent of calculus formation can be extreme. In these populations, supragingival calculus is associated with the promotion of gingival recession. Subgingival calculus, in "low hygiene" populations, is extensive and is directly correlated with enhanced periodontal attachment loss. Despite extensive research, a complete understanding of the etiologic significance of subgingival calculus to periodontal disease remains elusive, due to inability to clearly differentiate effects of calculus versus "plaque on calculus". As a result, we are not entirely sure whether subgingival calculus is the cause or result of periodontal inflammation. Research suggests that subgingival calculus, at a minimum, may expand the radius of plaque induced periodontal injury. Removal of subgingival plaque and calculus remains the cornerstone of periodontal therapy. Calculus formation is the result of petrification of dental plaque biofilm, with mineral ions provided by bathing saliva or crevicular fluids. Supragingival calculus formation can be controlled by chemical mineralization inhibitors, applied in toothpastes or mouthrinses. These agents act to delay plaque calcification, keeping deposits in an amorphous non-hardened state to facilitate removal with regular hygiene. Clinical efficacy for these agents is typically assessed as the reduction in tartar area coverage on the teeth between dental cleaning. Research shows that topically applied mineralization inhibitors can also influence adhesion and hardness of calculus deposits on the tooth surface, facilitating removal. Future research in calculus may include the development of improved supragingival tartar control formulations, the development of treatments for the prevention of subgingival calculus formation, the development of improved methods for root detoxification and debridement and the development and application of sensitive diagnostic methods to assess subgingival debridement efficacy.