Assessment of the efficiency of dental excavation methods using laser speckle imaging.

This paper introduces a novel application of the laser speckle technique in dentistry, focusing on assessing the efficiency of dental excavation methods used to remove decayed tooth structure. The aim is to evaluate the efficiency of two chemo-mechanical agents and the high-speed drill using the laser speckle technique, which offers objective, non-invasive, and real-time evaluation capabilities. Extracted human primary molars with active occlusal carious lesions were sectioned into three parts, with each part allocated to one of three groups: Group 1 (Brix3000®), Group 2 (Papacarie DUO®), and Group 3 (High-speed drill mechanical caries removal). Caries removal was performed using the designated agent or method for each group. After caries excavation, speckle imaging using a 632.8 nm laser was conducted. Additionally, SEM was used to acquire micro-photographs of the surface morphology of the treated samples. The findings reveal insights into the comparative efficiency of the three dental excavation agents and methods using the laser speckle technique. The speckle parameters extracted from speckle patterns generated by treated teeth provide valuable information for evaluating the performance of the excavation methods. The scanning electron microscopy images also offer detailed visual evidence to support the analysis. This paper demonstrates the potential of the laser speckle technique for assessing the efficiency of dental excavation methods. The objective, non-invasive, and real-time evaluation provided offers advantages over subjective visual assessment and manual measurements.

The Effectiveness of Different Irrigation Techniques on Debris and Smear Layer Removal in Primary Mandibular Second Molars: An In Vitro Study.

AIMS: The aim of the present in vitro study was to compare the effectiveness of passive ultrasonic irrigation (PUI), sonic irrigation, and mechanic dynamic activation on the removal of debris and smear layer from primary mandibular second molars during pulpectomy. MATERIALS AND METHODS: Mesial roots of 48 primary mandibular second molars were prepared with an R-motion 21 mm file (30/0.04) (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland), irrigated with 1% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA), and divided into four groups (n = 24 canals) according to the final irrigation activation technique: control group without activation, PUI with Ultra-X (Eighteeth, Changzhou, China), mechanical activation with XP-endo Finisher (FKG), and sonic irrigation with EQ-S (Meta Biomed, Chungcheongbuk-do, Korea). The roots were split longitudinally and analyzed using scanning electron microscopy (SEM). The presence of debris and smear layer was assessed using a 5-grade scoring scale with 200× and 1000× magnification, respectively. The Kruskal-Wallis and Friedman tests were used for data analysis. RESULTS: The activation of the irrigant significantly improved debris and smear layer removal (p < 0.001). There was no significant difference between Ultra-X, XP-endo Finisher, and EQ-S (p > 0.05). No activation technique was able to completely eliminate debris and smear layer from the root canals of primary mandibular second molars. CONCLUSIONS: During pediatric pulpectomy, the irrigation protocol must include activation of the irrigation solutions using either ultrasonic, sonic, or mechanical activation techniques to enhance the removal of debris and smear layer for a better prognosis. CLINICAL SIGNIFICANCE: During root canal treatment on primary teeth, the clinician must incorporate an activation technique in the irrigation protocol to enhance the removal of debris and smear layer and increase the success of the treatment.

Effect of Inlays, Onlays and Endocrown Cavity Design Preparation on Fracture Resistance and Fracture Mode of Endodontically Treated Teeth: An In Vitro Study.

PURPOSE: To evaluate the fracture resistance and failure modes of endodontically treated mandibular molars restored with different designs of inlays, onlays and endocrowns. MATERIALS AND METHODS: Extracted mandibular third molars (n = 180) were used. An access cavity was prepared on the occlusal surface of each tooth and the roots were obturated with gutta percha. All specimens were randomly divided into 6 groups (n = 30/group) according to the cavity design and the restoration material used. C: control group without access cavity preparation. IE: MOD inlay preparation with EverX Posterior (GC Europe) in the pulp chamber. IG: MOD inlay preparation with G-aenial Universal Flo (GC America) in the pulp chamber. OE: onlay preparation with EverX Posterior (GC Europe) in the pulp chamber. OG: onlay preparation with G-aenial Universal Flo (GC America) in the pulp chamber. EC: endocrown with an empty pulp chamber. All restorations were fabricated with CAD/CAM system using CERASMART® (GC Dental products Europe, Belgium) CAD/CAM blocks. Specimens were thermal-cycled and were subjected to a compressive load applied at 30° angle relative to the long axis of the tooth with a universal testing machine. Results were statistically analyzed by ANOVA followed by Tukey post hoc tests. Chi-square test and Fisher Exact tests were used for the comparisons among groups. RESULTS: The mean fracture strength was significantly different between the groups (p < 0.001); it was significantly highest for intact teeth, followed by endocrowns (p = 0.021). The strength was significantly lower for inlays (with G-aenial Universal Flo and EverX Posterior), intermediate for onlays with EverX Posterior followed by onlays with G-aenial Universal Flo. CONCLUSIONS: Endocrowns exhibited higher fracture resistance than other tested composite resin groups. Endocrowns and onlays showed a more favorable failure mode than inlay restorations.

Characteristics of Pediatric and Medically Compromised Patients Treated under General Anesthesia in a Middle Eastern Country.

AIM: This study aims to describe dental treatment provided to healthy and medically compromised patients treated under general anesthesia (GA) over a four-year period. MATERIALS AND METHODS: A total of 97 patients who received dental treatment under GA at the Saint Joseph University, Lebanon, from 2016 to 2019 were included in the study. The study population was analyzed according to the patient's age, medical status, and type of treatment done accordingly. RESULTS: The mean age of the patients was 9.15 ± 8.84 years. About 58.8% were aged below 6 years (primary dentition) and 48.5% had medical problems. Dental procedures performed were mostly extractions (4.00 ± 4.15 per patient) followed by resin composite restorations (3.66 ± 3.02 per patient). The mean number of pulpotomies per patient (p <0.001) and stainless steel crowns (p <0.001) were significantly higher in primary dentition, whereas in permanent dentition, the mean number of endodontic treatments per patient (p = 0.016) was significantly larger. Also, there was a significant difference between the type of treatment done on healthy and medically compromised patients (p <0.001). CONCLUSION: Better emphasis on oral health education and preventive strategies for children and special need patients is essential. CLINICAL SIGNIFICANCE: Dental GA is a reliable treatment for young uncooperative children and medically compromised patients. A multidisciplinary treatment plan must be conducted to ensure optimal oral healthcare and avoid unnecessary extractions.

Dentinal tubule penetration of AH Plus, BC Sealer and a novel tricalcium silicate sealer: a confocal laser scanning microscopy study.

OBJECTIVES: The aim of this in vitro study was to assess the dentinal tubule penetration of three different sealers, AH Plus, BC Sealer and a novel tricalcium silicate sealer (NTS). MATERIALS AND METHODS: Ninety-six human maxillary central incisors were divided into three experimental groups (n = 32) and were filled with gutta-percha using a single-cone technique in conjunction with one of the three sealers: AH Plus, BC Sealer or NTS. The roots in each group were cross-sectioned at 1 and 5 mm from the root apex, and the surfaces were examined under confocal laser scanning microscopy (CLSM). The sealer penetration depths were measured at their maximum depths and at four circumferential depths (12, 3, 6 and 9 o'clock) and were evaluated using ImageJ software (ImageJ, NIH). RESULTS: The maximum and mean penetration depths were significantly higher at 5 mm compared to 1 mm from the apex in the AH Plus (p < 0.001), BC Sealer (p < 0.001) and NTS groups (p < 0.001). No significant difference was observed between the groups at 1 mm for both parameters. The maximum and mean penetration depths were significantly lower at 5 mm for AH Plus compared with the other two groups (p = 0.012). CONCLUSIONS: Within the study limitations, the BC Sealer and NTS demonstrated better tubule penetration results than the AH Plus sealer. CLINICAL RELEVANCE: Although no study has confirmed a relationship between the penetration depth of root canal sealers and the prevention of apical periodontitis, dentinal tubule sealer penetration may improve obturation quality.

The influence of simulated aging on the color stability of composite resin cements.

STATEMENT OF PROBLEM: Data for the color stability of dual-polymerized and light-polymerized resin cements used in esthetic dentistry are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the color stability of 4 types of composite resin cements after water aging. MATERIAL AND METHODS: Specimens (n=30) of each resin cement (Variolink Esthetic LC, RelyX Ultimate DC, Nexus 3 DC, Nexus 3 LC) were prepared. The shade selected was Light+ for Variolink Esthetic, B 0.5 for RelyX Ultimate, and White for both Nexus 3 DC and LC. All 120 specimens were aged by water for 30 days at 37°C under dark conditions, using a thermocycling machine. The specimens' color characteristics (L*, luminosity; a*, red-green; b*, yellow-blue) and color differences (ΔE) were measured with a spectrophotometer before day 0, after day 1, and after 30 days of immersion. Statistical analysis used ANOVA and Tukey post hoc tests (α=.05). RESULTS: Considering ΔE<3.3 as clinically acceptable, results showed significant color variations for all cements (RelyX Ultimate=3.69; Nexus 3 LC=3.76; Nexus 3 DC=5.34), except for Variolink Esthetic (0.88). However, this variation was significantly less when day 1 was considered the baseline measurement, showing clinically acceptable ΔE values for all types of cement. CONCLUSIONS: Water aging had a significant effect on color stability; most color variations occurred in the first 24 hours of polymerization, with relatively nonsignificant variations afterwards.

Prevalence of Hypodontia and Supernumerary Teeth in Patients Attending Private Pediatric Dental Clinic in Lebanon.

Purpose: Because of the high rate of agenesis and supernumerary teeth in orthodontic patients and the lack of studies in Lebanon that document the prevalence of those anomalies, the aim of this study was to determine the prevalence of hypodontia and supernumerary teeth in patients attending a pediatric dental office and examine the associated factors. Study design: This was a cross-sectional design study. The patients were clinically examined followed by panoramic radiograph. Two calibrated investigators have examined the radiographic films and diagnosed the dental anomalies. Tooth agenesis and supernumerary teeth were the outcome variables of the study. Tooth agenesis was diagnosed when there were no sign of crown calcification and no evidence or history of loss attributable to orthodontic treatment, caries, periodontal problems and dental trauma. Tooth agenesis and supernumerary teeth were the outcome variables of the study. Chi-Square tests and Fisher Exact tests were performed to assess the association between outcome variables, gender and presence of medical problem. Results: 334 participants (mean age 7.31±2.17 years) were included in the study. The presence of dental anomalies was not reported as a reason for dental visits. The rate of tooth agenesis was 8.7% in the whole sample, 9.9% among boys and 7.6% among girls with no difference (p=0.442). The rate of tooth agenesis was elevated in participant with medical problems (14.5%) compared to those with no medical problem (7.0%) (p=0.041). The rate of supernumerary teeth was 0.6% among boys and 0% among girls (p=0.485). Conclusion: Oral anomalies could be detected relatively at early age. It can help in a long-term and effective treatment planning. Early diagnosis and appropriate follow-up with panoramic radiograph is extremely important to avoid maxillofacial deformity and other complications.

Effect of Cyclic Dislodging on the Retention of Two Attachment Systems for Implant-supported Overdentures: An In Vitro Study.

PURPOSE: The aim of this study was to compare and evaluate the retention of two new attachment systems used for implant-supported overdentures subjected to insertion-removal cycles. MATERIALS AND METHODS: Twenty custom-manufactured polyvinyl chloride models mimicking implant-retained over-dentureresin blocks were fabricated and divided into two groups (n = 10): group 1 ('Kerator' attachment) and group 2 ('EMI' attachment). Each model received two parallel implants (JD evolution®) 20 mm apart and was subjected to cyclic retention forces of 10, 100, 1000, 5000, 10000 and 14600 cycles using a universal testing machine in a 0.9% sodium chloride water solution at 22° C. Data were analyzed using one-way analysis of variance; the level of significance was set at a < 0.05. RESULTS: The 'Kerator' and 'EMI' attachment systems reported a significant decrease in retention (64 and 56.6% respectively) after 14600 insertion-removal cycles (p < 0.001). The 'EMI' attachment showed significant higher loss of retention than the 'Kerator' attachment all along the 14600 cycles (p < 0.05) except for cycles 100 and 5000 (p > 0.05). CONCLUSION: Within the limitations of this in vitro study, both attachments reported satisfactory retentive values during the 14600 cycles, the 'Kerator' attachment showed better retention than the new 'EMI' attachment. The initial retentive force of both attachments has gradually decreased. CLINICAL SIGNIFICANCE: Both attachment systems evaluated in this study can be used in clinical practice for implant-supported overdentures.

AGE AND REASONS OF THE FIRST DENTAL VISIT OF CHILDREN IN LEBANON.

BACKGROUND: The American Academy of Pediatrics and the American Academy of Pediatric Dentistry have recommended that the child's first dental visit should be during the child's first year of life for dental disease prevention and to decrease the invasive restorative interventions. In Lebanon, no study has been conducted to determine the age and the reasons of the first dental visit of children and who requested the first dental screening. OBJECTIVES: To assess at what age occurred the first dental visit in a group of Lebanese children visiting a private pediatric dental clinic and to explore the reasons for their first dental consultation. MATERIALS AND METHODS: An observational cross-sectional study was conducted. During a five-year period, all children visiting the pediatric clinic were invited to participate in the study. Parents were asked about the general health status of their child, the use of antibiotics before the age of 2 years. Parents were also requested to give the dental reasons for their initial visit to a pedodontist. RESULTS: Two hundred and twenty children (mean age 4.24 ± 1.35 years) visited the pedodontic care office for the first time and were included in the study. All participants had visited a pediatrician before the age of 1 year. Fifty-seven (25.9%) children were referred by a dentist and 163 (74.1%) came with their parents without referral. All participants had at least one reason for the first consultation; the most common were the presence of decayed teeth (50.9%) and a dental pain perception (29.5%). CONCLUSION: All participants had visited a pediatrician at an earlier age but none was referred to a pedodontist by a pediatrician for check-up or prevention. Children came upon the decision of their parents. A dental problem was the major reason which triggered the first visit. Therefore, pediatricians in Lebanon need to keep themselves updated on recommendations regarding children oral health and be encouraged to play an important role in prompting oral health and first dental visits.

Impact of breast vs. formula feeding mode on primary teeth lead level. Retrospective clinical study and literature review.

UNLABELLED: Lead exposure is a global environmental problem inducing lifelong adverse health effects. Children's exposure to lead, from birth to 6 months, is typically dominated by dietary sources. The first primary mandibular molar could provide an integrated record of lead exposure. The aim of this study is to detect the level of lead in the first primary molar of a group of Lebanese children born between 1990 and 2000, living in Beirut and suburbs, and to compare the amount of lead according to gender and feeding mode. MATERIALS AND METHODS: A group of 53 first primary molars belonging to 53 Lebanese children (31 girls and 22 boys), and aged 9 to 12 years old, were included in the study. The primary outcome variable of the study was the amount of lead level (mg/kg) in the first primary mandibular molars taken at the time of the natural exfoliation and measured by ICP/MS (Inductively Coupled Plasma Mass Spectrometry). Children included in the study were fed exclusively with formula feeding or maternal feeding for six months. RESULTS: The mean lead level of the first primary molar was 0.678 mg/kg +/- 0.717. The mean lead was significantly higher among children fed with instant formula milk (0.876 +/- 0.802) than breastfed children (0.455 +/- 0.540), (p = 0.044). No significant difference was found between girls (0.595 < or = 0.548) and boys (0.794 +/- 0.905), (p = 0.440). CONCLUSION: Within the limitations of this study, we found a statistically significant difference in the teeth lead level between breastfeeding and formula feeding, in favor of breastfeeding. This difference proves once more the importance of breastfeeding ; on the other hand, the Lebanese children accumulated lead in their teeth to levels below the international levels.

Fracture Resistance of Direct versus Indirect Restorations on Posterior Teeth: A Systematic Review and Meta-Analysis.

The aim of this systematic review and meta-analysis was to compare static compression forces between direct composite resin restorations and indirect restorations for posterior teeth. All studies comparing mechanical properties of direct versus indirect restorations of posterior teeth were included from 2007 up to February 2024. A meta-analysis was conducted for static compression fracture resistance. Medline, Central, and Embase databases were screened. Twenty-four articles were included in the qualitative synthesis, and sixteen studies were finally included in the quantitative synthesis. There was no difference in terms of fracture resistance between direct and indirect restorations for posterior teeth (p = 0.16 for direct and indirect composite resin restorations and p = 0.87 for direct composite resin restorations and indirect ceramic restorations). Also, sub-group analysis with or without cusp coverage in each group revealed no discernable difference. Based on this study, it can be concluded that the choice between direct and indirect restoration approaches may not significantly impact fracture resistance outcomes. There was no statically significant difference between direct and indirect restorations for posterior teeth in all cases of restorations with or without cusp coverage and no matter the used materials. However, to better evaluate these materials, further studies are warranted.

In vitro comparison of the color degradation of two computer-aided design/computer-aided manufacturing provisional materials: A 12-month simulation.

Aim: This study evaluated the color aging of two computer aided design/computer aided manufacturing (CAD/CAM) provisional materials of different compositions (polymethyl methacrylate and composite resin) after exposure to thermal aging and immersion in coffee for 3, 6, and 12 intraoral months. Setting and Design: The current in vitro study was conducted from September to December 2021 at the Craniofacial laboratory at the Saint Joseph University in Beirut, Lebanon. Materials and Methods: The shades of 2.0 mm thick, 10.0 mm in diameter disk shaped specimens of VITA CAD Temp® and Ceramill® TEMP were measured using the VITA Linearguide 3D MASTER® and a conversion table to extract the CIE LFNx01aFNx01bFNx01 values on a white background (n = 30). Statistical Analysis Used: The color differences ΔE at 3, 6, and 12 months were calculated and analyzed by repeated measures ANOVA followed by Bonferroni multiple comparisons, univariate analyses, and one sample t tests. Results: The mean ΔET1/T0, ΔET2/T0, and ΔET3/T0 values were significantly higher than the cutoff values for acceptability and perceptibility for the VITA CAD Temp® and the Ceramill® TEMP groups. In addition, the increase in ΔE overtime was significantly greater in the Ceramill® TEMP group compared to the VITA CAD Temp® group. Conclusions: The Ceramill® TEMP changed color more and faster than the VITA CAD Temp®. In addition, whether at 3, 6, or 12 months, the color variations of both materials are not only perceptible but also unacceptable compared to the initial shade.

In vitro evaluation of the color stability and surface roughness of a new composite flow.

Background: The aim of this study was to evaluate the color stability and the surface roughness of a bulk-fill composite flow (SDR® Plus) by comparison to an ORMOCER-based composite (Ceram.x® Universal SphereTEC™) in order to confirm the validity of using SDR® Plus in the anterior region and to allow the prediction of its long-term results. Material and Methods: 35 composite specimens of the same shade (A2), thickness (2mm) and shape of both types of composite were prepared. The specimens were cured and polished according to the manufacturer's instructions. The initial shade of the specimens was measured using a calibrated EasyShade spectrophotometer. The initial surface roughness of the specimens was measured by AFM. Afterwards, the specimens were subjected to an accelerated aging procedure through thermo-cycling, a coffee stain challenge and brushing to simulate two years in the oral environment. The shade and surface roughness of the specimens were measured again after the accelerated aging procedure. Results: The mean ΔE was significantly larger than 3.368 in Ceram.x® group (-p-value<0.001) and SDR® Plus group (-p-value<0.001). The mean surface roughness has significantly increased for both groups after aging with no significant difference between the two groups. It however remained clinically acceptable. Conclusions: SDR® Plus and Ceram.x® showed similar surface roughness when subjected to the same testing conditions. Concerning the color stability, both composites displayed noticeable discoloration, with higher ΔE values registered for Ceram.x®. Key words:Composite resins, spectrophotometry, atomic force microscopy, dental material, resin-based material.

Er,Cr:YSGG Laser Surface Modification Effect on Dentin Bonding to Zirconia: An In Vitro Study.

Objective: This study investigated the effect of dentin surface treatment with the erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser on the bond strength of zirconia to dentin. Background data: Although it is well-known that resin cement (RC) provides adequate bond strength of zirconia restorations to the tooth structure, many clinicians were not convinced in bonding reliability to zirconia materials. So, they preferred cementing their crowns with glass-ionomer cement (GIC). Pretreating the dentin surface is recommended to improve the adhesion of crowns cemented with GIC or RC. Recently, the Er,Cr:YSGG laser has been widely used for a cavity preparation, conditioning the tooth structure. However, there is not enough research on the bond strength of zirconia crowns cemented on a Er,Cr:YSGG laser-treated dentin. Methods: Forty-eight molars were cut horizontally at the crest of curvature. The flat dentin surface of 24 molars was left untreated, whereas the dentin surface of the other half was treated using an Er,Cr:YSGG laser 2.78 µm (4.5 W, 8.18 J/cm2, 90 mJ, 60 µs, 50 Hz, 60% air and 80% water). In addition, 48 plates of zirconia were prepared to be cemented with GIC or RC on the dentin surface. So, the molars were divided into four groups as follows: GIC+untreated dentin; GIC+treated dentin; RC+untreated dentin; and RC+treated dentin. All the specimens were subjected to shear bond strength test. The mode of failure was determined and additional samples were prepared to evaluate the cement-dentin interface using a scanning electron microscope. Data were analyzed with two-way analysis of variance accompanied by univariate analyses. Results: The bond strength of zirconia cemented with GIC or bonded with RC significantly increased on a Er,Cr:YSGG laser-treated dentin surface (p < 0.05). Conclusions: Dentin preconditioning with an Er,Cr:YSGG laser significantly improved the bond strength of zirconia plates to dentin as compared with untreated dentin.

Lack of Correlation Between the Penetration of Two Types of Sealers and Interfacial Adaptation to Root Dentine.

OBJECTIVE: This study aimed to determine the correlation between sealer penetration into dentinal tubules and interfacial adaptation to root canal walls using a hydraulic calcium silicate-based sealer, Endosequence Bioceramic Sealer (Brasseler USA, Savannah, GA, USA), and an epoxy resin-based sealer, AH Plus (Dentsply DeTrey, Konstanz, Germany). METHODS: Sixty-four maxillary central incisors were endodontically prepared with nickel-titanium rotary instruments and randomly assigned into two groups (n=32). Roots were filled with gutta-percha using a single-cone technique in conjunction with one of the two sealers, AHP or BCS. Sealers were mixed with Rhodamine B and analysed under a confocal laser scanning microscope. Transverse sections at 5 mm from root apex were obtained. The circumference of the root canal wall was first outlined and measured to determine the circumferential percentage of sealer penetration. The regions along the canal walls where the sealer had penetrated the dentinal tubules were delineated and measured. Then, the outlined distances were divided by the canal circumference. The width of each gap was measured and pooled for each specimen for comparison to determine the interfacial adaptation. The measurements were repeated twice to ensure reproducibility. Mann-Whitney tests were performed to compare continuous variables between AHP and BCS groups. The correlation between gap width and percentage of sealer penetration was investigated using the Spearman correlation coefficient. RESULTS: No significant difference was observed between groups regarding the percentage of sealer penetration (P>0.05) and the gap width (P>0.05). Also, there was no significant correlation between the two variables analysed for AHP (r=0.165; P>0.05) and BCS (r=-0.147; P>0.05) and in the overall sample (r=0.061; P>0.05). CONCLUSION: The present results show no correlation between interfacial adaptation and sealer penetration in dentinal tubules in the total sample and among sealer subgroups. The ability of root canal sealers to penetrate dentinal tubules cannot be considered a sign of better interfacial adaptation.

Comparison of the force decay over time of four different brands of elastomeric chains (elongated to 25mm grey/transparent and closed/open): An in-vitro study.

Elastomeric chains are widely used by orthodontists for incisor retraction and space closure. However, force degradation and permanent deformation are expected to occur. OBJECTIVES: The present study was designed to compare the force degradation of closed, open, grey and transparent power chains from four orthodontic companies (American orthodontics® (AO®), Dentsply®, Ormco® and Rocky Mountain Orthodontics® (RMO®)) over time. MATERIALS AND METHODS: Universal testing machine was used to measure the force of the power chains elongated to 25mm at 0hours, and after storage in artificial saliva at 24hours, 1 week, 2 weeks, 3 weeks, and 4 weeks. A Tukey's honestly significant difference test was performed. RESULTS: Most of the power chains showed less than 30% of force decay at 24hours of elongation. The AO® transparent open elastomeric chains presented the lowest percentage of force remaining at almost all times: 24hours (58.9%), 1 week (67.7%), 2 weeks (43.2%), 3 weeks (72.4%), and 4 weeks (63%). Most of the power chains had an increase of force measured after 2 weeks of storage in artificial saliva. Three of the sixteen groups (Ormco® grey open, RMO® grey and transparent closed) displayed an increase in the force at 4 weeks of elongation compared to the force registered at 0hours. CONCLUSION: The results indicated that the force generated by elastomeric chains at 4 weeks remains optimal for a physiologic tooth movement.

Two-year clinical evaluation of three restorative materials in primary molars.

UNLABELLED: A variety of alternatives to amalgam are now available for use in Class I and Class II restorations in primary teeth, including glass ionomer cements, compomers and resin modified glass ionomer cements (RMGIC). OBJECTIVES: This study evaluated the two-year clinical performance of three restorative dental materials: A resin modified glass ionomer cement (Fuji IILC), a compomer (Dyract AP) and a high viscosity glass ionomer cement (Fuji IX), in primary molars of pediatric patients with high caries risk activity and compared these results to those reported for amalgam restorations. STUDY DESIGN: One hundred and forty nine Class I and Class II cavities in 45 patients aged 6 to 8 years were restored with compomer, glass ionomer cements and amalgam. Restorations were evaluated according to modified Ryge criteria by two examiners at baseline, and after 6, 12, 18 and 24 months of oral function. The data was submitted to statistical analysis (binomial and hyper geometric tests, p<0.05). RESULTS: Two-year recall rate was 62.42%. Class I performed better than class II restorations. The difference in marginal discoloration between compomer and amalgam restorations was statistically significant (p=0.014). No other significant differences were found between GIC, compomer and amalgam restorations. The clinical performance of the three restorative materials compared to amalgam in Class I and Class II cavities at two-year recall was acceptable. CONCLUSIONS: The results, even in a population with high caries risk activity, suggest that these materials are suitable alternatives to amalgam in Class I and Class II restorations in primary teeth.

Clinical success of compomer and amalgam restorations in primary molars. Follow up in 36 months.

The purpose of this study was to evaluate the three-year clinical performance of a compomer and an amalgam in primary molars and to determine fluoride content in the enamel of these teeth after exfoliation. Twenty patients aged six to eight years randomly received one compomer and one amalgam restoration. Restorations were evaluated at baseline, 12, 24 and 36 months according to modified USPHS criteria. In six pairs of exfoliated teeth fluoride content at 1 and 5 mm distance from the restorations was determined. Replicas were made to determine marginal adaptation (MA) by scanning electron microscopy (SEM). At occlusal margins compomer restorations had better MA than amalgam restorations (p < 0.01). Compomer and amalgam restorations did not lead to different fluoride uptake in adjacent enamel and had an overall clinically satisfactory performance. The study confirmed that the assessed compomer is a suitable restorative material for class I and class II restorations in primary molar teeth.

Clinical evaluation of four different dental restorative materials: one-year results.

The purpose of the present study conducted in a school in Lebanon was to evaluate the one-year clinical performance of a polyacid-modified resin composite (PMC), a resin-modified glass ionomer cement (RMGIC), a high viscosity GIC (HVGIC) and an amalgam (Amlg). Hundred and forty-nine class I and class II cavities in 45 patients aged 6 to 8 years, with a high caries risk activity, were restored with these materials. Restorations were evaluated by two examiners at baseline, 6 and 12 months, according to USPHS criteria. Evaluation at 12 months showed that the retention of materials in class I and class II restorations in primary teeth was good. The recall rate was 97.4%. None of the restorations were clinically unacceptable, except for those with secondary caries (9/138). RMGIC gave the best results. At one year, RMGIC had the highest percentage of intact marginal integrity. Marginal discoloration in PMC restorations compared to Amlg restorations was statistically more important (p = 0.013). Secondary caries in HVGIC restorations, compared to Amlg restorations, were higher (p = 0.013). Clinical performance of the 3 restorative materials compared to Amlg in class I and class II cavities at one-year recall is not uniform. The results suggest that RMGIC is a suitable alternative to Amlg for restorations in primary teeth. Restrictions should be considered for the materials with more secondary caries (HVGIC) and higher marginal discoloration (PMC).

Impact of Minimal Root Canal Taper on the Fracture Resistance of Endodontically Treated Bicuspids.

OBJECTIVE: Minimal invasive endodontics preserve coronal and radicular tooth structure to increase the fracture resistance of teeth. The aim of this study was to assess the influence of final preparation taper on the fracture resistance of maxillary premolars. MATERIALS AND METHODS: Sixty maxillary premolars were selected and divided into 2 groups: 30 were shaped with a final apical diameter 30 and a 4% taper and 30 with 6% taper using iRaCe® instrument (FKG dentaire, Switzerland). All root canals were irrigated with sodium hypochlorite and final rinse with ethylenediaminetetraacetic acid. All canals were filled with gutta-percha single-cone filling technique and AHPlus® sealer (Dentsply- Maillefer, Baillagues, Switzerland) and access cavity restored with resin composite. Roots were wax coated, placed in an acrylic mold and loaded to compressive strength fracture in a mechanical material testing machine recording the maximum load at fracture and fracture pattern (favorable/restorable or unfavorable/unrestorable). Fracture loads were compared statistically, and data examined with Student t-test with a level of significance set at P ≤ 0.05. RESULTS: No statistically significant difference was registered between the 4% taper of preparation (270.47 ± 90.9 N) and 6% taper of preparation (244.73 ± 120.3 N) regarding the fracture resistance of the endodontically treated premolars tested (P = 0.541), while more favorable restorable fractures were registered in the 4% taper group. CONCLUSIONS: Continuous 4% preparation taper did not enhance the fracture resistance of endodontically treated maxillary premolars when compared to a 6% taper root canal preparation. More fractures were registered in the 4% taper group.