A split-mouth randomized controlled trial to compare the rate of canine retraction after a soft tissue procedure compared against a corticotomy procedure for accelerated tooth movement

Background and Aim

Various methods to accelerate the orthodontic tooth movement have been used, among which corticotomy is considered to be the most common one. The suggested reasoning for such acceleration was the regional acceleratory phenomenon (RAP). Since the RAP is a property of both the hard and soft tissues, we designed a soft tissue flap procedure to compare the effects with the conventional corticotomy procedure. A split-mouth study was conducted where the two procedures were assessed in a single participant.

Patients and Methods

The total sample size was calculated to be 40 with 20 participants in each group. The rate of tooth movement was the primary outcome measure, and the secondary outcomes were dentoalveolar changes, which were studied in both the conventional corticotomy and the flap-only procedure based on a cone-beam computed tomography (CBCT) wherein the alveolar bone density (BD) around canines, tipping, and rotational changes in canines, premolars, and molars were assessed.

Results

Corticotomy resulted in greater canine angulation, lesser canine rotation and premolar rotation, and greater molar rotation compared with flap elevation, but these differences were statistically insignificant.

Conclusion

Though the corticotomy resulted in higher BD, the differences were statistically insignificant. There was no significant difference in the rate of space closure assessed by the two techniques compared.

Anti-microbial efficacy of root canal preparation in deciduous teeth with manual and rotary files: A randomized clinical trial

BACKGROUND

In a pulpectomy, the eradication of microbes from the primary root canal is accomplished through biomechanical preparation, which could be carried out with either manual or rotary instruments.

AIMS

The objective of this clinical trial was to evaluate the efficiency of manual K-files, H-files, and Kedo-S Square rotary files in reducing microbial flora after canal preparation in primary molars.

MATERIALS AND METHODS

This randomized clinical trial consisted of 45 primary molars requiring pulpectomy. The teeth were randomly allocated to one of the three groups: Group I: Manual K-files, Group II: Manual H-files, and Group III: Kedo-S Square rotary files, based on the type of instrumentation. Pre-and Post-instrumentation sampling was performed using clean absorbent paper points and kept in a clean Eppendorf tube having thioglycolate broth as the transport medium. Culturing was performed on agar media from which both aerobic and anaerobic microbial counts were estimated. Collected data were statistically analyzed using one-way analysis of variance (ANOVA) and Wilcoxon signed-rank test. Following root canal preparation, 87-89% reduction of the aerobic and anaerobic microbial load was noted in group I, whereas it was an 89-92% reduction in group II and a 93-95% reduction in group III.

RESULTS

Biomechanical preparation with Kedo-S Square rotary file showed higher efficacy in microbial reduction compared to manual instrumentation.

CONCLUSION

Manual and rotary files were equally effective in removing root canal microbes. Biomechanical preparation with a KedoS Square rotary file resulted in greater microbial efficacy. Hence In children, effective root canal cleaning in a short period of time is a major consideration.

Effect of a laser-ablated micron-scale modification of dental implant collar surface on changes in the vertical and fractal dimensions of peri-implant trabecular bone

BACKGROUND

Marginal bone loss (MBL) represents an important indicator of peri-implant health and the measure of its level is considered a determining factor in the evaluation of the quality of survival. Aim of this study is to compare radiographic changes in the fractal and mesial/distal vertical dimensions of peri-implant trabecular bone of dental implants with a laser-ablated micron-scale modication (LAM) of collar surface after a 5-year follow-up period.

MATERIALS AND METHODS

Thirty-four implants with LAM of collar surface (test group = TG) and 31 implants without LAM of collar surface (control group = CG) were placed in 45 non-smoking, periodontally healthy patients. Fractal and vertical dimensions of peri-implant trabecular bone were measured by comparing radiographs taken immediately after prosthesis delivery with those taken 3 years and 5 years after functional loading.

RESULT

At the end of the 5-year follow-up, the MBL in the TG was 0.87±0.21 and 0.75±0.25 mm at the mesial and distal aspects, respectively, while a MBL of 2.05±0.25 mm at the mesial aspect and 2.01±0.34 mm at the distal site was recorded in the CG. A statistically significant difference was noted. In the TG the mean fractal dimension before loading was 1.4213±0.0525. It increased significantly to 1.4329±0.0479 at 3 years after loading and remained almost stable at 5 years after loading (1.4327±0.0291). In the CG the mean fractal dimension before loading was 1.4119±0.0414. It increased significantly to 1.4282±0.0324 at 3 years after loading and decreased significantly to 1.4111±0.0624 at 5 years after loading. At the end of the follow-up, differences between both study groups were statistically significant.

CONCLUSION

The increased fractal dimension and the reduced MBL around TG implants after 5 years of functional loading indicates a positive effect of a laser-ablated micron-scale modication of collar surface on peri-implant trabecular bone remodeling.

C-shaped canal configuration in mandibular premolars and molars: Prevalence, correlation, and differences: An In Vivo study using cone-beam computed tomography

AIMS

To evaluate the prevalence, correlation, and differences of C-shaped canal morphology in mandibular premolars and molars by means of cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

A total of 1433 mandibular premolars and molars CBCT scans from the Saudi population were evaluated. Axial sections of the roots were acquired at coronal, middle, and apical levels to evaluate C-shaped canals types. The prevalence, correlation, differences of C-shaped canals, bilateral/unilateral presence, gender differences, and location of external grooves on roots were assessed.

RESULTS

The prevalence of C-shaped canals in the first premolars was 1.5%, 0.80% in second premolars and 7.9% in second molars, whereas C-shaped canals were absent in first molars. No correlation was found between the presence of C-shaped canals within premolars and molars and between the two groups in the same individual. Both premolars and molars exhibited different types of C-shaped canals, C2 being predominant in premolars and C3 in second molars. Longitudinal external grooves were mostly located on mesiolingual (ML) surface in premolars and lingual in molars. Females showed more prevalence of C-shaped canals in second molars and no differences in premolars. Bilateral symmetry and unilateral presence in premolars and second molars were not significant.

CONCLUSIONS

Although the prevalence of C-shaped canals is significantly higher in mandibular second molars, they are also found in mandibular premolars but in small percentages. No significant differences were found between both genders and both sides. Since they exhibit unpredictable morphology and differences across the root length, the use of small field CBCT is recommended when such anatomy is presented in a tooth indicated for root canal treatment for better management.

Microbial contamination of brand new nickel-titanium endodontic instruments

AIMS

This study aims to estimate the microbial presence on the surface of different brand new NiTi endodontic instruments for clinical use.

MATERIAL AND METHODS

Eleven different types of NiTi rotary endodontic instruments, obtained from their fresh opened original packages, were assigned to three different groups, according to packaging type and sterilization and tested for bacterial contamination. Isolated bacteria were identified by using standard microbiological methods and then counted. Differences observed in groups were analyzed statistically by using the one-way analysis of variance (ANOVA) for dependent samples and the Tukey HSD post hoc test.

RESULTS

Statistical differences were found between instruments delivered in plastic boxes which bacterial count resulted higher than those obtained from instruments delivered in blisters (p<0.01).

CONCLUSIONS

Some brand new endodontic instruments showed degrees of bacterial contamination that both quantitatively and qualitatively deserve to be considered in clinical procedures.

Full arch fixed prostheses vs. full arch telescopic-retained retrievable prostheses both supported by implants and natural tooth abutments in periodontally treated patients: Results at 15 years

Background

The clinical outcome of full arch fixed prostheses vs. full arch telescopic-retained retrievable prostheses supported by implants and natural tooth abutments in periodontally treated patients has been reported by few studies, with controversial results. The objective of this study was to evaluate long-term (15 years) complications of abutment teeth and dental implants in periodontally treated patients, rehabilitated with full arch telescopic-retained retrievable prostheses (TRP)s vs. full arch fixed prostheses (FP)s supported by teeth and implants.

Material and Methods

After active periodontal therapy (non-surgical and surgical), and implant placement (replacement of hopeless teeth and in edentulous sites), 18 patients were rehabilitated in both dental arches with full arch TRPs, and 17 patients were rehabilitated with full arch FPs. Patients were annually recalled for technical and/or biological complications monitoring.

Results

During the 15-year observation period, 29 of 164 (17.6%) implants failed in the TRP group and 26 of 152 (17.1 %) implants in the FP group. Due to progression of periodontal disease, endo-perio untreatable lesion and caries, 22 of 233 abutment teeth were extracted (8.1) % in the TRP group and 23 of 221 (10.4%) abutment teeth were extracted in the FP group. Difference in implant failures and abutment teeth loss between the two groups were found not statistically significant (p >0.05). Poisson regression analysis showed that in both groups, factors such as smoking habits, FMBS>20, number of pockets >6 mm, mean bone loss, and bone loss/age, contribute to tooth and implant failure (p<0.05).

Conclusions

In this clinical study, in periodontally treated patients, full arch telescopic-retained retrievable prostheses, and full arch fixed prosthesis, supported by teeth and implants presented comparable long-term results of tooth loss and implant failure, if regular periodontal therapy is implemented.

Key words:Periodontal disease, implants, tooth-implant connection, telescopic prosthesis, fixed prosthesis.

Fatigue Resistance of New and Used Nickel-Titanium Rotary Instruments: a Comparative Study

OBJECTIVES

Aim of the present study was twofold. First, to evaluate in vitro, the performance of two different NiTi rotary instruments in one molar case; then, to evaluate their resistance to cyclic fatigue, compared to new ones.

MATERIAL AND METHODS

25 ProTaper Next (PTN) nickel-titanium (NiTi) instruments (Maillefer-Dentsply, Baillagues, CH) for each of the following two sizes: X1 (17.04 ) and X2 (25.06) were randomly divided into two groups. The first group (n = 10) immediately under- went to a cyclic fatigue test. The second group (n = 15) was initially used to prepare 15 extracted molar teeth and then subjected to a cyclic fatigue test. Same was done for 25 Horizen (HZ) instruments (Kerr Endodontics, Orange, Ca) for each of the following two sizes: 20.04 and 25.06. Instruments were rotated in curved artificial canal until fracture occurred and times to fracture were recorded. All data were collected and statistically analyzed using a variance test (confidence interval CI = 95%).

RESULTS

HZ reached working length more rapidly than PTN, and with less deformations. For the fatigue tests, all the new instruments were significantly more resistant than the used ones. The HZ instru- ments were significantly more resistant in all sizes than PTN, both when new and used instruments were tested.

CONCLUSIONS

Since in previous studies ProTaper Next demonstra- ted a better resistance to cyclic fatigue than most of nickel-titanium instruments, Horizen's performance put them in a high rank amongst the most resistant nickel-titanium rotary instruments.

The Influence of a New Clinical Motion for Endodontic Instruments on the Incidence of Postoperative Pain

OBJECTIVES

Previous studies showed that motor motions play an important role in determining apical extrusion of debris. Therefore a new clinical motion (MIMERACI) has been proposed. The basic idea is to progress slowly (1mm advancement), and after each 1mm, to remove the instrument from the canal, clean flutes and irrigate. The aim of the study was to prove whether the clinical use of MIMERACI technique would influence or not postoperative pain.

MATERIALS AND METHODS

100 teeth requesting endodontic treatment were selected for the study and divided into two similar groups based on anatomy, pre-operative symptoms and vitality, presence or absence of periapical lesion. All teeth were shaped, cleaned and obturated by the same operator, using the same NiTi instruments. The only difference between the two groups was the instrumentation technique: tradional (group A) vs MIMERACI (group B). Assessment of postoperative pain was performed 3 days after treatment. Presence, absence and degree of pain were recorded with a visual analogue scale (VAS), validated in previous studies. Collected data statistically analyzed using one-way ANOVA post hoc Tukey test.

RESULTS

For VAS pain scores MIMERACI technique showed significantly better results than group A (p=0,031). Overall, both incidence and intensity of symptoms were significantly lower. Flare ups occurred in 3 patients, but none treated with the MIMERACI Technique.

CONCLUSIONS

Since extruded debris can elicit more postoperative pain, results obtained by using MIMERACI technique are probably due to many factors: better mechanical removal and less production of debris and more efficient irrigation during instrumentation.

Cyclic fatigue of Reciproc and WaveOne reciprocating instruments

AIM

To evaluate the cyclic fatigue resistance of Reciproc(®) and WaveOne(®) instruments in simulated root canals.

METHODOLOGY

Two groups of 15 NiTi endodontic instruments of identical tip size of 0.25 mm were tested, group A; Reciproc(®) R25 and group B: WaveOne(®) primary. Cyclic fatigue testing was performed in a stainless steel artificial canal manufactured by reproducing the instrument's size and taper. A simulated root canal with a 60° angle of curvature and 5-mm radius of curvature was constructed for both the instruments tested. The centre of the curvature was 5 mm from the tip of the instrument and the curved segment of the canal was approximately 5 mm in length. The Reciproc(®) instruments were activated using the preset programme specific for the Reciproc(®) instruments, whilst the WaveOne(®) instruments were activated using the preset programme specific for the WaveOne(®) instruments. All instruments were rotated until fracture occurred and the time to fracture (TtF) and the length of the fractured tip were recorded and registered. Means and standard deviations of TtF and fragment length were calculated for each system and data were subjected to Student's t-test (P < 0.05).

RESULTS

A statistically significant difference (P < 0.05) was noted between Reciproc(®) and WaveOne(®) instruments. Reciproc(®) R25 instruments were associated with a significant increase in the mean time to fracture when compared with primary WaveOne(®) instruments (130.8 ± 18.4 vs. 97.8 ± 15.9 s). There was no significant difference (P > 0.05) in the mean length of the fractured fragments between the instruments.

CONCLUSIONS

  Reciproc(®) instruments were associated with a significantly higher cyclic fatigue resistance than WaveOne(®) instruments.

Oral Focal Mucinosis of the Tongue: A Rare Clinical Case

Oral focal mucinosis (OFM) is a rare mucosal lesion of unknown etiopathogenesis. It is considered the oral counterpart of cutaneous focal mucinosis. From the anatomo-pathological point of view it is characterised by a focal degeneration of myxoid type of connective tissue. A literature survey revealed 50 reports of OFM cases worldwide. Here, we present an even more rare case with tongue involvement. Particular emphasis is placed on diagnostic-differential aspects of this kind of lesion, both from the clinical and the histopathological point of view, in respect to other manifestations of tongue mucosa.

Incidence and Intensivity of Postoperative Pain and Periapical Inflammation after Endodontic Treatment with Two Different Instrumentation Techniques

Apical extrusion of infected debris to the periradicular tissues is considered one of the possible factors related to the occurrence of postoperative pain and inflammation. The goal of the present study is to evaluate and compare the incidence and intensity of postoperative pain using two different nickel-titanium instrumentation techniques: a rotary crown-down technique using TF instruments (SybronEndo, Orange, Ca, USA) and a reciprocating single-file technique using Reciproc instruments (VDW, Munich, Germany). Sixty patients requiring endodontic treatment on permanent premolar and molar teeth with non-vital pulps preoperatively were included in the study. The patients were divided into two groups of 30 patients each, trying to make the groups very similar, concerning the number of root canals, presence of initial pain and periapical lesions. The teeth in group 1 (n = 30) were treated with a crown-down technique using TF instruments whilst those in group 2 (n = 30) were treated with, a single-file technique using Reciproc 08 25. All canals were shaped, cleaned and obturated in a single-visit. The assessment of postoperative pain was carried out at 3 days by using a visual analogue scale. CAi-square tests and independent-sample t-tests to compare the incidence and intensity of postoperative pain of two groups were carried out. A statistically significant difference was found between the two techniques. When comparing patients who developed no pain, the TF instrumentation technique showed significantly better results ( chi-square = 4.059 P = 0.039). When evaluating patients experiencing severe pain the incidence of symptoms was significantly higher with the Reciproc technique ( chi-square = 7.246 P = 0.023). Since the incidence of preoperative pain, the type of tooth and the pulp and periodontal pathology were quite similar between the two tested groups, and all the other variables (operator, irrigation, and obturation) were identical, the difference in postoperative pain can be mainly related to the different instrumentation technique

Biocompatibility of Root Canal Filling Materials: Differences between Vitality and Functionality Tests

Biocompatibility of root canal filling materials is of great interest because they can come into permanent contact with the living periapical tissue, and induce mild or severe inflammatory responses. Usually biocompatibility tests only determine non-cytotoxic effects of dental materials, even if their functional interactions with cells also play a role in the host responses. The purpose of this study is to evaluate peripheral blood monocyte (PBM) vitality and functionality after contact with 5 different root canal filling materials: Thermafil (gutta-percha), Real Seal and Real Seal 1 (methacrylic resins), AureoSeal (MTA) and SuperSeal (EBA). Cellular vitality was determined by MTT test and cellular functionality by Chemiluminescence (CL) technique. Dishes of the materials were covered with cell culture medium (0.5 cm2/mL) and incubated for 24 h. The extracts were added to PBMs and the latter, after 2 h of incubation, were analysed by MTT and by Chemiluminescence (CL). All results are expressed as mean ± SEM. The group means were compared by analysis of variance. Results showed that SuperSeal and AuroSeal exhibited a moderate cytotoxic effect, while the toxicity induced by RealSeal, RealSeal 1 and Thermafil was lower. SuperSeal and AuroSeal induced a significant decrease of both oxidative burst and basal reactive oxygen species (ROS) production. RealSeal 1 caused a doubling of basal ROS production in respect to control. The results demonstrate that a low cytotoxic effect does not guarantee a total integrity of cellular functionality and more differences among biocompatibility of root canal materials can be detected when a functionality test is used.

The effect of a new finishing process on the torsional resistance of twisted nickel-titanium rotary instruments

AIM

The process of twisting has been used for decades to fabricate stainless steel instruments, but it was previously thought to be an impractical method for nickel-titanium (Ni-Ti) instrument manufacture A manufacturing method of twisting Nickel-Titanium wire to produce Ni-Ti files has been recently developed: the twisted files (TF). Theoretically, this new manufacturing process should overcome the problems associated with a grinding process, which previously limited instrument strength. Since TF manufacturing process is new and different from grinding, the aim of the present study was to evaluate the effects of a final deoxidation process (Deox) on torsional resistance of TF instruments.

METHODS

Testing was performed in accordance with the International Standard (ISO 3630-1) by comparing 20 TF instruments versus 20 TF prototype instruments produced without the final deoxidation process. Data were collected and statistically analyzed (t-test).

RESULTS

Results show that TF instruments withstood 90% more torque (max. torque) than TF prototype instruments manufactured without the deoxidation process (88.7 vs. 53.3 g/cm). This difference was found to be statistically significant at the 0.05 level of significance.

CONCLUSION

Since design and dimensions of tested instruments were the same, the deoxidation process could be the only explanation of the improvement in torsional resistance.

Cyclic fatigue of NiTi rotary instruments in a simulated apical abrupt curvature

AIM

To evaluate the cyclic fatigue resistance of five NiTi rotary systems in an abrupt apical curvature.

METHODOLOGY

Cyclic fatigue testing was performed in stainless-steel artificial canals with a 2-mm radius of curvature and an angle of curvature of 90 degrees constructed to the dimensions of the instruments tested. The middle of the simulated curvature was 2.5 mm from the tip of the instrument that was placed at full working length. All instruments were new and 25 mm in length. Ten ProTaper Universal F2 (Dentsply Maillefer, Ballaigues, Switzerland); FlexMaster (VDW, Munich, Germany) tip size 25, taper 0.06; Mtwo (Sweden & Martina, Padova, Italy) tip size 25, taper 0.06; ProFile tip size 25, taper 0.06 from Dentsply Maillefer (Ballaigues, Switzerland); and ProFile tip size 25, taper 0.06 from Dentsply Tulsa (Tulsa, OK, USA) were rotated passively at 300 rpm until fracture occurred, and the number of cycles to failure (NCF) recorded. Length of the fractured tip was measured. Data were analysed by one-way anova and Tukey HSD test to determine any statistical difference amongst groups.

RESULTS

Mtwo had the highest fatigue resistance compared to the other instruments (NCF 124 +/- 25) (P < 0.001); there was no statistical difference between ProFile from the two different brands, although ProFile from Maillefer had the higher fatigue life (NCF 75 +/- 10) compared to ProFile from Tulsa (NCF 66 +/- 10). No difference was registered between FlexMaster (NCF 53 +/- 5) and ProFile from Tulsa; ProTaper F2 had a significantly (P < 0.001) lower fatigue life compared to the other instruments tested (NCF 29 +/- 5).

CONCLUSIONS

Lifespan registered for the instruments tested in an apical abrupt curvature was Mtwo > ProFile from Maillefer > ProFile from Tulsa > FlexMaster > ProTaper.

Sealing ability of a new carrier-based obturating material

AIM

The aim of the present study was to investigate the in vitro sealing ability of a new obturating material (Real Seal 1, SybronEndo, Orange, CA, USA) and compare it with the Thermafil (Dentsply Maillefer, Baillargues, Switzerland) and One-Step systems (CMS Dental, Copenhagen, Denmark).

METHODS

Forty-four freshly extracted lower premolars teeth were selected and a root canal treatment was performed using a crown-down Nickel-Titanium rotary preparation technique. Teeth were randomized into three groups (N.=14): 1) Thermafil group; 2) One/step group; 3) Real Seal 1 (RS1) group. The remaining two teeth served as controls. A fluid filtration system device was utilized to assess quantitatively the microleakage. Statistical analyses were performed by ANOVA and significance was set at 95%.

RESULTS

Data clearly showed that the RS1 provided the best results, showing a minimal leakage after 24 hours. Statystical analysis showed a significant difference about the RS1 group, the Thermafil and One/Step group, while no significant differences were noted between these last two groups. Results show that the number of teeth that had no (=0) leakage was higher in the RS1 group (8 specimens) than in the remaining ones (1 and 1 specimen, respectively).

CONCLUSIONS

Under the conditions of the present experimental test, the new RS1 material (carrier-based Resilon) provided excellent preliminary results showing sealing ability at 24 hours significantly better that traditional carrier-based gutta-percha systems.

[Not Available]

Since the introduction of nickel-titanium alloy to endodontics, there have been many changes in instrument design, but no significant improvements in the raw material properties, or enhancements in the manufacturing process. Recently, a new method to produce nickel-titanium rotary (NTR) instruments has been developed, in an attempt to obtain instruments that are more flexible and resistant to fatigue. NTR instruments produced using the process of twisting (TF, SybronEndo, Orange, CA) were compared to NTR instruments from different manufacturers produced by a traditional grinding process. The aim of the study was to investigate whether cyclic fatigue resistance is increased for TF NTR files. Tests were performed with a cyclic fatigue device that evaluated cycles to failure of rotary instruments inside curved artificial canals. Results indicated that size 06-25 TF instruments showed a significant increase (P< .05). In the mean number of cycles to failurewhen compared to the other tested 06-25 NTR. Hence, it can be concluded that size 06-25 TF NTR instruments were found to be significantly more resistant to fatigue than those produced with the traditional grinding process.

Bending properties of nickel-titanium instruments: a comparative study

AIM

The aim of the present study was to evaluate the bending properties of twisted file instruments, and compare them with other commercially available nickel-titanium (NiTi) instruments (Mtwo and Hero) manufactured with traditional methods.

METHODS

Despite NiTi superelastic properties, flexibility of NiTi instruments is limited by size and taper. A new manufacturing process involving twisting of a ground blank combined with heat treatment has been developed by SybronEndo, aiming to produce a NiTI rotary file with superior flexibility: the Twisted File (TF). Experimental procedures strictly followed the testing methodology described in ISO 3630-1. Bending moment was measured when the instrument attained a 45 degrees bend. Data were collected and statistically analyzed.

RESULTS

Results showed that TF were the most flexible instruments, with a significant improvement in flexibility (P< 0.05). ranging from 100% to 250% over the other tested instruments. Even if flexibility is also influenced by instruments design, such a great improvement is mainly related to the new TF manufacturing process.

CONCLUSION

The flexibility is influenced by instruments design, such a great improvement is mainly related to the new manufacturing process developed by SybronEndo, which seems to play a major role in increasing the flexibility of TF instruments.

Detection of DNA from periodontal pathogenic bacteria in biofilm obtained from waterlines in dental units

Direct person-to-person transmission of periodontal bacteria through saliva has recently been widely reported and dental units have been demonstrated to retract saliva from patients under treatment and to release it into the mouths of subjects undergoing the next operation. In this study the presence of a group of periodontal pathogenic bacteria inside waterlines in dental units was investigated using polymerase chain reaction (PCR) based methods. Briefly, 18 dental units of three different manufacturers were studied. Dental units were divided into two groups according to their prevalent use in routine practice. The first group consisted of nine dental units characterized by the frequent use of high-speed dental hand-pieces directly inside the mouth and in contact with patients' saliva. The second group, as a control, consisted of nine dental units where high-speed dental hand-pieces were not in use. A one cm section of the waterline tubing connected to the high-speed hand-piece was removed from each dental unit to evaluate the presence of DNA of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Treponema denticola. Two specimens were positive for Prevotella intermedia DNA. All the positive results were from samples obtained from dental units categorised in the first group. These findings clearly suggest that dental units have the potential to transmit periodontal pathogens. Manufacturers should be invited to design dental units that incorporate automated devices to disinfect DUWLs between patients with minimal effort by dental staff.

Infection through sprays in medical devices for dentistry. A controllable epidemiological impact

The risk of infections via dental sprays has been confirmed once again by the detection, inside dental unit waterlines, of bacterial and viral contaminations, both from water supplies and from the oral cavity of patients. Conventional means of prevention, flushing of the ducts before any dental treatment and anti-retraction devices intended to avoid contamination originating from the patient, evaluated in laboratory and clinical conditions, have been shown to be ineffective in controlling the risk. Tests carried out in vitro, with circuit models, and with the dental unit in service, have confirmed the efficacy of a method to disinfect the waterlines with a disinfecting solution based on TAED and Peroxidant, which in aqueous solution develop peracetic ions (Autosteril method). Zero bacterial count, zero viral charge and a complete biofilm demolition were achieved both in lab conditions and in service units. After hygienic treatment, the same disinfection method, once installed on old units that had been in service for years and without any hygienic device, allowed us to restore and to maintain the microbiological quality of the irrigant also in dental units of old design, and significantly reduced biofilm formation inside the waterlines. Therefore, on the basis of scientific findings, a microbiologic monitoring protocol is proposed in order to verify the hygienic conditions of units which are in service.

The challenge of severe acute respiratory syndrome (SARS) in dentistry

Severe Acute Respiratory Syndrome (SARS) is caused by a newly identified coronavirus, called SARS-associated coronavirus (SARS-CoV) that appears to be transmitted primarily through droplets of saliva. This is the reason why the most important international organizations recommend that the dentists adopt a unique preventive approach to the problem: SARS patients should not be treated in the dental office. This is possible only if a suspected case of SARS is correctly and promptly identified. But a correct identification is made difficult by several factors, such as the incubation period, a possibly asymptomatic onset of the illness, the still low specificity and sensitivity of laboratory and instrumental tests. A case or suspected case of SARS may thus unwillingly be treated at the dental office. It is therefore necessary to adopt protective measures for the dental personnel and to implement and enforce infection control measures in order to eliminate the risk of viral contamination. Nonetheless, these procedures do not ensure a complete elimination of SARS-CoV contamination risk since a major risk is represented by blood-borne infection, which is originated by the mouth of patients, and the contamination of dental units water lines (DUWLs) is most difficult to control. Blood-borne contamination may be achieved only by adopting a high level, between-patients disinfection protocol of the DUWLs based on the use of chemical agents with biocidal activity against spores, viruses, bacteria and fungi (Autosteril method). In conclusion a fully effective control of the cross-infection risk will be obtained only by adopting a correct, integrated use of different infection control procedures.

Cytotoxicity of a new endodontic filling material

In vitro cell cultures have been widely used as a means of evaluating cytotoxicity of root canal filling materials. Following ANSI/ADA spec. no. 41, the aim of the present study was to investigate the biological compatibility of a new sealer (FibreFill) and compare it with some commercially available endodontic sealers (Bioseal and Acroseal). Mouse 3T3 fibroblasts were seeded and cultured and subsequently extracts of the cements were added. After 24 hours incubation, the cellular vitality of fibroblasts was evaluated by the neutral red uptake test (NRU), which measures the membrane permeability. Data were collected and statistically analysed. Results showed that all tested materials exhibited mild cytotoxic effects, which are compatible with normal clinical use, and no statistically significant difference was noted between FibreFill and the other tested materials. Therefore, selection amongst these sealers should be based on other factors.

[Mechanical properties of nickel-titanium files following multiple heat sterilizations]

AIM

The effect of cycles of sterilization procedures on nickel-titanium (NiTi) endodontic instruments is a serious concern for practitioners. There is no agreement in the literature whether these procedures could adversely affect the mechanical properties of endodontic files, and, consequently, increase the risk of intracanal failure. The purpose of this study was to evaluate the mechanichal resistance of Hero (MicroMega, Besancon, France) instruments, before and after sterilization procedures.

METHODS

Thirty 02, 04, 06 tapered Hero size 30 new instruments were chosen and divided into 3 groups. Group A (control) were tested according to ANSI/ADA Spec.no 28 for torsional resistance, angle of torque and angle at breakage (45 inverted exclamation mark ). Group B files were first sterilized with chemiclave for 10 cycles of 20 minutes at 124 inverted exclamation mark C and then tested as described above. Group C files were first sterilized with glass beads for 10 cycles of 20 sec. at 250 inverted exclamation mark C and then tested as described above. Data were collected and statistically analyzed (t-paired test). Differences among the 3 groups were statistically not significant for both tests.

RESULTS

All data were well within Spec.no 28 standard values.

CONCLUSION

From the results of the present study, we may conclude that repeated sterilization procedures do not adversely affect the mechanichal resistance of Hero files.

[In vitro evaluation of five root canal sealers]

BACKGROUND

An adequate film thickness is an important property of an endodontic sealer, when used in combination with gutta-percha, to eventually fill minimal voids between gutta-percha and the root canal walls, ensuring an hermetic three-dimensional root canal obturation. The goal of the present study was to evaluate the film thickness of the following five root canal sealers: RSA, Rocanal R4, N2, Bioseal and Acroseal.

METHODS

The testing procedures strictly followed ANSI/ADA spec. no. 57 for endodontic filling materials. All root canal sealers were mixed at room temperature strictly following mixing procedures advised by manufacturers. A small amount of sealer was placed between two glass plates and load of 147 N was applied vertically on the top glass plate. After 10 min, the thickness of sealers was measured by a micrometer assembled on a stereomicroscope (Lomo MBC 10). Data were collected and statistically analysed.

RESULTS

Results (expressed in micron) were the following: RSA=9,3 (+/-1), Rocanal R4 95 (+/-12), N2 50 (+/-23), Bioseal 41 (+/-13) and Acroseal =9 (+/-2.55).

CONCLUSIONS

RSA and Acroseal showed the best results (a statistically significant difference was noted among these sealers and the others). On the other hand Bioseal and (partially) N2 showed values compatible with a valid clinical use, while Rocanal R4 showed values higher than minimum standard values allowed by ANSA/ADA spec. no. 57.