A review of the latest developments in rotary NiTi technology and root canal preparation.

The introduction of nickel-titanium (NiTi) mechanical instruments dramatically changed clinical endodontics over the last few decades. Before NiTi, it was necessary to use more instruments to create an ideal root canal shape, and many approaches, sequences and techniques were developed over the years. Recently, NiTi endodontic instruments have undergone a series of changes brought about by modifications in design, surface treatments, and thermal treatments to improve their root canal preparation outcomes and reduce associated canal preparation risks during root canal treatment. Heat treatment is one of the most fundamental approaches to improving the fatigue resistance and flexibility of NiTi endodontic instruments. In addition, new kinematics have been developed to offer greater safety and efficiency. This narrative review describes the general properties and manufacturing of NiTi instruments, and the mechanical system evolution of NiTi instruments.

Short lingual frenum in infants, children and adolescents. Part 2: Lingual frenum release. Functional surgical approach.

AIM: The aim of this study was to review the craniofacial growth impairment and different malfunctions associated with short lingual frenum and to assess the validity of lingual frenum surgery based on minimally invasive laser release with a myofunctional approach. MATERIALS AND METHODS: Thirty patients, children and adolescents whose ages ranged from 8 years to 18 years, diagnosed with a short lingual frenum and concomitant orthodontic problems and/or presence of associated muscular or postural problems, were treated in this study. Pre-operative tongue assessment was performed following morphological and functional criteria, consisting of measurement of the free tongue, and of visual assessment of tongue protrusion out of the mouth and elevation to the incisive palatal papilla. Postural evaluation was assessed in frontal and lateral view. Laser surgery was completed with local anaesthesia, using Erbium YAG laser (2940 nm, LightWalker, AT-Fotona, Ljubljana, Slovenia) equipped with sapphire conical tip (600 micron), with energy ranging from 120 to 160 mJ, at 15 Hz frequency, and varying the adjustable pulse duration from 300 µs to 600 µs. RESULTS: Significant improvement was noted in 29 of 30 patients comparing preoperative scores to both three-week and two-month post-op scores. Postural improvement was found in 18 of 30 patients, indicating the multifactorial involvement of different causes for correct body posture. CONCLUSION: This study confirmed the validity of Erbium:YAG laser surgery as an effective technique in children and adolescents to release a short lingual frenum. The functional approach of the procedure performed with the Erbium:YAG laser, and the concomitant myofunctional therapy demonstrated to be simple and safe in children, and adolescents. Because of the multifactorial causes involved in correct body posture, an adequate osteopathic therapy is important to successfully complete the full body rehabilitation.

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

OBJECTIVES: To evaluate the efficacy of a stepwise intraoperative activation (SIA) of irrigants during and after the instrumentation compared with that of a conventional activation (CA) performed only after the instrumentation to remove smear layer and debris using different activation devices. MATERIALS AND METHODS: A total of 70 single-rooted teeth were divided into a control group (no activation, n = 10) and two different experimental groups according to the irrigant activation protocol used: group 1 (CA), in which sodium hypochlorite was activated only after the use of the last mechanical file, and group 2 (SIA), in which activation was performed during and after the instrumentation. The two groups were divided into 3 subgroups according to the activation device used (n = 10): passive ultrasonic irrigation (PUI, subgroup a), EndoActivator (EA, subgroup b), and EDDY (subgroup c). The roots were split longitudinally and observed using scanning electron microscopy (SEM) to evaluate the presence of debris and smear layer, and the results were statistically analyzed. RESULTS: All activation protocols and devices were more effective than control group in removing smear layer and debris from all root canal thirds (P < 0.05), except for CA-EA (group 1b) in the apical third. In the apical third, SIA was found to be more effective than CA (P < 0.05) to remove smear layer and residual debris when PUI was used, to remove the smear layer when EA was used (P < 0.05), and to remove residual debris when EDDY was used (P < 0.05). PUI and EDDY removed statistically more smear layer and debris than EA in the apical third (P < 0.05). CONCLUSIONS: The SIA technique improved the smear layer and debris removal from the apical third and debris removal from the coronal third, and PUI and EDDY were more effective than EA in the apical third. CLINICAL RELEVANCE: The stepwise intraoperative activation (SIA) technique may increase smear layer and debris removal.

Short lingual frenum in infants, children and adolescents. Part 1: Breastfeeding and gastroesophageal reflux disease improvement after tethered oral tissues release.

AIM: This study aimed to determine the impact of laser surgical tongue-tie, lip-tie, buccal tie release on breastfeeding and Gastroesophageal Reflux Disease (GERD) in a prospective cohort study conducted from June 2019 to June 2020 in a private general dental practice. MATERIALS AND METHODS: Preoperative, one-week and one-month postoperative surveys were completed, consisting of Visual Analogue Scale (VAS) for nipple pain severity, Breastfeeding Self-Efficacy Scale Short Form (BSES-SF), and the Revised Infant Gastroesophageal Reflux Questionnaire (I-GERQ-R). All study participants were breastfeeding dyads (0-12 weeks of age) with untreated ankyloglossia and/or tethered maxillary/buccal frena. The laser surgery was completed using 2 different near- infrared diode lasers with 300µm diameter fibre: a 980 nm wavelength diode laser (Lasotronix Smart Pro, Piaseczno Poland) was used at 4.0 W, gated with 100 µs t/on and 100 µs t/off, and a 1470 nm wavelength diode laser (Pioon S1, Wuhan Pioon Tech Co Ltd., Wuhan, China), used at 3.5W, gated with 50 ms t/on and 50 ms t/off. RESULTS: Statistically significant improvement was noted in VAS, I-GERQ-R and BSES-SF comparing preoperative scores to both one-week and one-month scores. The study had 132 breastfeeding dyads enrolled. Posterior tongue-tie was noted in 71% of this cohort. CONCLUSION: This study confirms the need for functional assessment of tongue and lip movement for this significantly affected cohort. Laser surgical release (frenotomy) of tongue-tie, lip-tie, buccal-tie resulted in significant improvement in breastfeeding outcomes. These improvements (VAS, I-GERQ-R and BSES-SF) in breastfeeding outcomes were found for cohorts of the classically recognised anterior tongue-tie and the less obvious (without functional assessment) submucosal tongue-tie were found.

Micro-CT evaluation of two different root canal filling techniques.

OBJECTIVE: The aim of this study was to compare the frequency and volume of voids in root canals obturated with two different filling techniques using micro-computed tomography (micro-CT). MATERIALS AND METHODS: Forty single-rooted permanent teeth were selected and decoronated. The roots were instrumented with WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) to a large size until working length and irrigated with 5.25% sodium hypochlorite and 17% EDTA. Then, the samples were filled using a single-cone (n = 20) or the GuttaCore technique (n = 20). The presence and volume (mm3) of voids (internal, external, and combined) was calculated in the coronal, medium, and apical thirds using micro-CT (SkyScan 1072; SkyScan, Kartuizersweg, Belgium). Statistical analyses were performed using the χ2-test and Kruskal-Wallis tests (p<0.05). RESULTS: The frequency and total volume of voids in the middle third and the external voids in the coronal third were statistically significant (p<0.05). Within the same group, both techniques (single-cone and Guttacore) showed statistically significant differences in external and internal voids (p<0.05). CONCLUSIONS: The GuttaCore technique showed better results in the coronal and medium thirds than the single-cone technique. Our results showed that the single-cone and GuttaCore techniques were comparable in the apical third (p>0.05).

Reasons for and consequences of vitamin K antagonist discontinuation in very elderly patients with non-valvular atrial fibrillation.

Essentials Anticoagulation in the elderly is still a challenge and suspension of warfarin is common. This is an observational study reporting reasons and consequences of warfarin suspension. Vascular disease, age, time in therapeutic range, and bleedings are associated with suspension. After suspension for bleeding or frailty, patients remain at high-risk of death or complications. SUMMARY: Background Anticoagulation in elderly patients with non-valvular atrial fibrillation (NVAF) is still a challenge, and discontinuation of warfarin is common. The aim of this study was to analyze the aspects related to warfarin discontinuation in a real-world population. Methods This was an observational cohort study on very elderly NVAF patients naive to warfarin therapy (VENPAF). The included subjects were aged at least 80 years, and started using warfarin after a diagnosis of NVAF. Warfarin discontinuation was assessed, and the reason reported for discontinuation, the person who decided to stop treatment, subsequent antithrombotic therapy and mortality, ischemic and bleeding events were collected. Results Over a period of 5 years, warfarin was discontinued in 148 of 798 patients. Despite similar CHA2 DS2 -VASc scores, the frequencies of thromboembolic and major bleeding events were significantly higher (P = 0.01 and P = 0.001, respectively) and the time in therapeutic range (TTR) was significantly lower (P < 0.001) in patients who discontinued warfarin. Independent risk factors for warfarin discontinuation were vascular disease (hazard ratio [HR] 2.5, P < 0.001), age ≥ 85 years (HR 1.4, P = 0.04), TTR < 60% (HR 1.8, P = 0.001), and bleeding events (HR 2.3, P < 0.001). The main reasons for warfarin discontinuation were physician-perceived frailty or low life-expectancy (45.9%), bleeding complications (19.6%), and sinus rhythm restoration (16.9%). Event and death rates were very high, especially in frail patients and in those with bleeding complications. Conclusions Warfarin discontinuation is frequent in very elderly patients, and is associated with increased risks of death and adverse events. Identification of elderly patients who are at high risk of bleeding and the poor quality of anticoagulation during warfarin are still unsolved clinical problems.

Relation between conversion degree and cytotoxicity of a flowable bulk-fill and three conventional flowable resin-composites.

OBJECTIVE: The aim of this study is to evaluate if the cytotoxic effects of the Surefil SDR flow, bulk fill flowable composite resin and three conventional flowable materials (Venus Diamond Flow, Filtex Supreme XTE Flowable and Enamel plus HRi Flow) correlated with the conversion degree (DC); hardness and depth of cure are also assessed. MATERIALS AND METHODS: Disks of each materials--cured using LED lamp--are utilized to evaluate DC (by FT-IR technique), amount of leached monomers (by HPLC technique), hardness (by Vickers hardness tester) and cytotoxicity (by MTT test). RESULTS: All tested materials show light cytotoxic effects, independently from DC values. Both the latter parameter and the hardness, in fact, change in function of thickness and type of material. HPLC results show that the monomers amount leached from each specimen is influenced by thickness but it is always very low which justifies the absence of any cytotoxic effect. CONCLUSIONS: Our findings suggest that there are not statistically significant differences in cytotoxicity in all experimental conditions, notwithstanding the differences in hardness and in degree of conversion.

Influence of simulated apical resorption following orthodontic treatment on working length determination: an in vitro study.

AIM: External apical root resorption (EARR) is a common complication that may occur during and after orthodontic treatment. In case of need of endodontic therapy for a tooth with EARR, it has not been clarified yet which benefits can be derived by the use of electronic apex locators (EALs). The present study aimed to assess the accuracy of EALs on extracted teeth before and after simulation of EARR subsequent to orthodontic treatment. MATERIALS AND METHODS: Standard access cavities were prepared on 64 single-rooted teeth. After working length (CWL) determination, specimens were embedded in an alginate mass, connected to two EALs (Apit, Osada, Tokyo, Japan; Root ZX, Morita Corp., Tokyo, Japan) and the electronic working length (EWL) was measured. The apical portion of the specimens was then modified to simulate EARR, and the EWL was determined again. The discrepancy between CWL and EWL was regarded as statistical unit. Collected data underwent statistical analysis by means of non-parametric tests (p < 0.05). RESULTS: Within a range of ± 0.5 and ± 1.0 mm from CWL, the accuracies were 79.7% and 98.4% (Apit/intact tooth); 82.8% and 96.9% (Apit/simulated EARR); 81.3% and 98.4% (Root ZX/intact tooth); 76.6% and 96.9% (Root ZX/simulated EARR). No statistically significant differences in relation to device or apical condition emerged (p > 0.05). CONCLUSION: The two considered EALs showed similar accuracy, which was not affected by the EARR simulation. The use of EALs in the treatment of teeth with EARR following orthodontic treatment may be useful.

Implant platform switching concept: a literature review.

BACKGROUND: The platform switching concept involves the reduction of the restoration abutment diameter with respect to the diameter of dental implant. Long-term follow up around these wide-platforms showed higher levels of bone preservation. AIM: The aim of this article is to carry out a literature review of studies which deal with the influence of platform-switched implants in hard and soft oral tissues. MATERIALS AND METHODS: All papers involving "platform switching" that are indexed in MedLine and published between 2005 and 2011 were used. Clinical cases, experimental and non-experimental studies were included, as well as literature reviews. RESULTS: In our search, we analized 18 clinical cases and 3 reviews. The results indicate that peri-implant bone resorption is reduced with platform switching system. CONCLUSIONS: All papers written by different researchers show an improvement in peri-implant bone preservation and satisfactory aesthetic results. Further long-term studies are necessary to confirm these results.

In vivo accuracy of three electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II.

AIM: To compare in vivo three different electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II. METHODOLOGY: Thirty single-rooted permanent teeth scheduled for extraction because of periodontal disease were selected from 10 adult patients (ranging from 45 to 67 years) and divided into three groups of 10 teeth. Before the extraction, an access cavity was prepared and the crown was adjusted to establish a stable reference point for all measurements. The working length in Group 1 was determined using the Dentaport ZX apex locator. A K-file with the largest diameter that could reach the last green bar on the screen was stabilized in the canal using a dual-curable flow resin composite. The same procedure was used for the Raypex 5 (the file reached the last yellow bar) and Propex II (0.0 orange bar) apex locators. The teeth were then extracted and cleared. The distance between the tip of the file and the major foramen was then calculated for each tooth using digital photography according to Axiovision AC software (Carl Zeiss). Positive values were assigned when the file tip passed beyond the major foramen, negative values when the tip was short of the foramen and zero value when the file tip and the foramen coincided. Statistical analysis was performed using the chi-squared test or Fisher's exact test (P ≤ 0.05). RESULTS: Dentaport ZX, Raypex 5 and ProPex ΙΙ produced, respectively, 6, 2 and 4 out of 10 correct measurements, 0, 6 and 5 long measurements and 4, 2, and 1 short measurements. The differences between the three electronic root canal length measurement devices were not significant (P = 0.507). CONCLUSIONS: Under the in vivo conditions of this study, the three electronic root canal length measurement devices were not significantly different in terms of locating the major foramen.

Diabetes mellitus: biochemical, histological and microbiological aspects in periodontal disease.

Relationship between diabetes mellitus (DM) and periodontal disease has been the subject of many studies that underline that diabetic patients are two/three times more susceptible to have an increased risk of periodontal disease, especially when metabolic control is inadequate. In this review the authors analyze, in diabetic patient, biochemical, histological and microbiological aspects of periodontal disease. Recent studies reported the results obtained in not diabetic patients, both periodontopatic and not: in periodontopatic subjects, the value of glycated hemoglobin was higher. As regards type 2 DM has a positive relationship between periodontal inflammation and glycemia, with good probabilities of disease development. Some Authors showed how the hygiene and the professional/domiciliary control could support a reduction of the glycate hemoglobin and, therefore, of the periodontal disease. The glucose accumulation in the crevicular fluid, noticed in pockets with a depth >4 mm, causes an increase of spirochetes and bacteria. Some research reported that scarcely controlled patients show high levels of interleukin-1beta (IL-1beta). This alteration together with the prolonged expression of tumor necrosis factor (TNF) could represent a mechanism used by bacteria to cause a major damage during the inflammation process, sometimes favoured by immunological defects, due to the mobilization of lymphocytes subpopulations. By measuring the values of TNF-a, fibrinogen, high sensitive capsule reactive protein (hs-CRP), IL-4, IL-6, IL-8, IL-10, at the beginning of non-surgical periodontal therapy and it has been after 3 months of treatment, noticed a relevant reduction only of TNF-a and fibrinogen. Concerning vascular alteration, vascular endothelium growing factor (VEGF) could play a major role in the tissues ischemia. The VEGF should determine the tissue ischemia, the angiogenesis and the alteration of glucose haematic level, in patients affected by microvasculopathies due to diabetes and to periodontal diseases. Particularly, the angiogenesis should favor the chronic inflammation, caused by increasing concentration of cytokines and other pro-inflammatory factors.

Oral inflammatory process and general health. Part 2: How does the periapical inflammatory process compromise general health?

At present, the focal infection theory still has very controversial aspects. In spite of the great number of studies, there is no evidence that focal infections or even antigenic mimicry are responsible for anything other than sporadic abscesses/infections and possibly rare autoimmune disorders. linflammation of endodontic origin (i.e., apical periodontitis--AP) has not received the same attention as inflammation originating from the periodontium. Endodontics is a microbiological problem, since the bacterial infection is the "prime mover" of pulp (before) and periapical (later) disease. The aims of endodontic treatment have to be considered from a microbiological viewpoint. Considering these problems in this second part of their study, the Authors, after close examination of the virulence of microorganisms and of the host defense, analyze the endodontic infection and microbiological species. They emphasize the possibility of a relationship between periapical inflammatory lesions and bacterial endocarditis in preventing metafocal disease. Bacterial endocarditis deserves special mention because despite involving specialists of two scientific fields, its prophylaxis is almost always assigned to medical practice, and especially, to dentistry. Given the dangers of the disease, antibiotic prophylaxis is both absolutely necessary and can be very effective, and it should be used especially in clinical situations with high risk individuals. However, the ability of antibiotic therapy to prevent or reduce the frequency, magnitude or duration of bacteremia associated with a dental procedure is controversial. Studies should also be undertaken to determine to compare the efficacy of endodontic treatment with alternative therapy such as implants, prosthetic replacements or no treatment other than extraction. To date, these studies have not been carried out, and there is no evidence to support the theory that modern endodontic therapy is not safe and effective.

Expression of parathyroid hormone-related protein in human inflamed dental pulp.

INTRODUCTION: The aim of this study was to investigate the presence and the role of the parathyroid hormone-related protein (PTH-rP) in the inflamed pulp. MATERIALS AND METHODS: Thirty-four pulp tissue specimens (24 inflamed and 10 normal pulps) from extracted third molars were studied. The presence of PTH-rP was observed by using immunohistochemistry. Negative controls were performed using non immunized rabbit or mouse serum, omitting the primary antibody. RESULTS: The analysis of all the sections of normal pulps showed the presence of PTHrP positive cells only in the odontoblastic zone and in few fibroblasts. Instead all inflamed pulps showed PTHrP positive cells both in vascular zone and in pulp stroma, as well as in the odontoblastic and subodontoblastic zone. CONCLUSION: Several works proved that this peptide plays a role even in angiogenesis process, but its function is controversial. It is possible to hypothesize that PTHrP stimulates angiogenesis, but it is recommended to further conduct research on this area.

Oral inflammatory process and general health. Part 1: The focal infection and the oral inflammatory lesion.

A focal infection is a localized or generalized infection caused by the dissemination of microorganisms or toxic products from a focus of infection in various organic districts, including the oral district. In the Part 1 of this two-part review article, after historical signs, the Authors describe the current pathogenic concepts like the "immuno-allergic theory" and the formation of auto-antibodies in human body, contributing to the genesis of autoimmune illnesses sustained by individual reactivity linked to eredo-constitutionality. Some theories suppose a focal origin even for general pathology such as cancer, sarcoidosis, multiple sclerosis, amyotrophic lateral sclerosis, autism, Guillain-Barré syndrome, Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS), Tourette's syndrome, myasthenia gravis, polycystic kidney disease, obesity, Alzheimer's disease and diabetes mellitus. Laboratory analyses (leucocytic formula, protein electrophoresis, C-reactive protein, REUMA test VES, TAS, etc.) are suggestive of the presence of an inflammatory process or of the presence of an aspecific answer to an inflammatory situation. The DNA-Polymerase Chain Reaction method (PCR) is fundamental for the diagnosis of bacterial and viral infections, particularly for those that have non-culturable microorganisms or in cases where are present but in extremely small number in the sample to be analyzed. A positive result confirms the diagnosis, but negative result is not indicator of the absence of illness. Even for oral inflammatory lesions, different basic mechanisms concerning the possible association with systemic diseases exist. They concern local spread, metastatic spread or immunologic cross-reactivity. In this case we assume that most of the ailments come from dental or periodontal foci, as in the bacterial endocarditis, but instead of considering them as possible pathogenetic mechanism of an immune nature, we consider them as originated by the body's response to the presence of bacterial antigens through the formation of specific antibodies. Much researche, sometimes contrasting, has evaluated periodontal pathogens in atheromatous plaques isolated from patients with chronic periodontitis. Oral inflammatory lesions have been shown unequivocally to contribute to elevated systemic inflammatory responses. In some researches intensive periodontal therapy showed a significant reduction of lymphocyte formula, of CRP levels, of interleukin-6 (IL-6) and of LDL cholesterol after two months.

Porphyrin-photosensitized processes: their applications in the prevention of arterial restenosis.

Photodynamic therapy (PDT) is based on the use of a photozensitising compound which is accumulated by rapidly proliferating cells. Subsequent irradiation with light wavelengths specifically absorbed by the photosensitiser promotes the generation of reactive short-lived oxygen species which cause an irreversible and selective damage. Endovascular interventions to correct obstructive arterial disease have been developed worldwide with excellent short term results. However, long term patency is still limited by the onset of restenosis, due to subsequent intimal hyperplasia (IH). IH is characterized by proliferation and migration of smooth muscle cells (SMC) and extracellular matrix production. Targeting of SMC by photozensitisers can be efficiently achieved by taking advantage of the receptors for low density lipoproteins (LDL) expressed by such cells. Thus, preference is given to hydrophobic compounds which readily partition in the lipid matrix of LDL. We developed a liposomal formulation of a highly hydrophobic photozensitising agent, Zn(II)-phthalocyanine (ZnPc). The liposome-delivered ZnPc was readily taken up by cultured SMC cells and preferentially localized in the Golgi apparatus. Red light irradiation of incubated SMC induced cell death. Extension of these investigations to an in vivo rabbit model showed that ZnPc mainly accumulated in the media layer, where PDT induces the main damage through cellular depletion due to apoptosis of SMC, changes in the extracellular matrix with generation of a barrier to cellular migration, and acceleration of re-endothelization. Initial clinical applications showed that PDT safely and effectively prevents restenosis after angioplasty up to a 6 month follow-up.

Probiotic treatment increases salivary counts of lactobacilli: a double-blind, randomized, controlled study.

BACKGROUND/AIMS: Lactobacilli are used in the prevention and treatment of several diseases, but they are also known to play a role in the pathogenesis of dental caries. The aim of our study was to evaluate whether the oral administration of lactobacilli could change the salivary counts of these bacteria compared with placebo. Moreover, lactobacilli were administered in liquid and in capsule form to determine the role of direct contact with the oral cavity. METHODS: Thirty-five healthy volunteers were randomized into three groups to receive lactobacilli and/or placebo for 45 days: group A (n = 14) received probiotics in capsules and placebo in liquid form; group B (n = 16) took liquid probiotics and placebo in capsules, and group C (n = 5) used placebo in both liquid and capsule form. Streptococcus mutans populations served as control. The salivary counts of lactobacilli and S. mutans were measured semi-quantitatively using the CRT bacteria kit. RESULTS: Compared with placebo, the oral administration of probiotics, both in capsules and in liquid form, significantly increases salivary counts of lactobacilli (p = 0.005 and p = 0.02, respectively). S. mutans populations were not significantly modified. CONCLUSIONS: The increased salivary counts of lactobacilli may indicate the need to closely monitor the dental health of patients undergoing long-term probiotics treatment, even when this treatment is administrated in a form that avoids direct contact with the oral cavity.

[Light-emitting diodes (LED) technology applied to the photopolymerization of resin composites]. / Tecnologia light-emitting diodes (LED) applicata alla fotopolimerizzazione delle resine composite.

An adequate polymerization of resin composites can significantly contribute to increase the longevity of a restoration. In this field, the choice of the operative technique and the characteristics of the lamp are very important. The aim of this review was to evaluate the effectiveness of cure of the light-emitting diodes (LED) lamps comparing them to the others currently available for resin composites photopolymerization. At present, halogen lamps are the most commonly used light sources, but this technology does not allow further developments; even plasma arc and laser lamps have some drawbacks. The innovative LED technology, based on semiconductors, opened new and interesting views in the field of photopolymerization; to the advantages of a soft-start polymerization they add the safety, efficiency, economy and long lifetime of LED light. A careful review of the literature revealed that, although their lower emission of light, these lamps are capable of a polymerization qualitatively comparable to other light sources. Physical and mechanical properties, degree of conversion, depth of cure and final hardness of the composites cured with a LED light are similar to the values achieved with the halogen lamp, whereas the temperature increase is significantly lower and does not pose a threat to the pulp tissue. Undoubtedly, more tests of the mechanical properties of composites processed with LED units need to be carried out but, as the technology improves, LED curing will become an interesting alternative to existing curing methods.

3-D surface profile analysis: different finishing methods for resin composites.

A microfilled and hybrid resin composites used for esthetic restoration were finished and polished using four methods: Enhance system, Sof-Lex system, Multi-step system and Identoflex points. The tested materials were condensed into cylindrical molds, covered with a Mylar matrix at the surface to be tested and incrementally cured according to manufacturers' instructions. Samples were randomized into four groups of three for each material and were finished/polished using the different methods. The samples were then analyzed by a 3-D surface profiler to obtain roughness average (Ra), root mean square value (rms), greatest distance peak-valley (PV), measure of profile about the center line (Rsk) and measure of steepness of the amplitude density curve of the roughness profile (Rku) directly from the tested area. This method offers the advantage of being error-free. All parameters were determined for each sample and the mean of each parameter was determined for each group. ANOVA and Sheffé's test were employed to determine whether significant differences existed. The Enhance and Multi-step systems gave the best finish and polish for both materials.

[Clinical observations on the nature of early caries. A study with scanning electron microscopy]. / Osservazioni cliniche sulla natura delle lesioni cariose iniziali. Studio al SEM.

BACKGROUND: Early caries lesions present a greater porosity in the deep layers than in the superficial layer of the enamel. The "white spot" lesion is a dynamic lesion which is subjected to the changes occurring in the oral cavity; it can regress, stabilize or progress. The aim of this study is to show if there are considerable morphological differences in the superficial ultrastructural aspect of early caries lesions, active or stabilized, in persons of different age. METHODS: To carry out this SEM observation, 15 patients aged from 12 to 50 presenting early caries lesions have been selected. Some of them had been recently subjected to orthodontic treatment, others several years ago. Five of these patients have been called back to examine again the demineralized area by microscope in the very same place of the first observation. The replica technique was used utilizing a silicon-based impression material, an epoxy resin for replicas casting, little steel nets to fix the silicon material. RESULTS: At the level of white spot lesions it is evident a tissural structure scattered with small overlappings and micropits with a diameter of 0.5-2 mu. The patients who removed orthodontic bands more than 10 years before show a shining white aspect, corresponding to the nearly complete loss of enamel perikymata with well defined abrasions, but without any micropits at SEM examination. CONCLUSIONS: The replica technique has shown to be useful to record the defects of active and stabilized caries lesions. However this technique can't be utilized as a diagnostic instrument because it would be too expensive, but it is certainly a valid support for in vivo research.

[Efficacy of 4 adhesive systems for amalgam. In vitro study]. / Efficacia di 4 sistemi adesivi per amalgama. Studio in vitro.

BACKGROUND: The aim of this research is to study the shear bond strength of 4 adhesive systems of the last generation: All-Bond 2 (AB2), Clearfil Liner Bond 2 (CL), Scotchbond MP plus (SBMP) and High Q Bond plus (HQB). According to the manufacturing company these products are suitable for amalgam adhesion to dentin. METHODS: Forty extracted human third molars have been ground to expose a flat dentin surface. The teeth were randomly assigned to 4 groups, and every group was treated with one of the adhesive system according to the manufacturer's instructions. Samples were then secured in a split Teflon mould, having a 6 mm diameter opening and a spherical amalgam was triturated and condensed onto the treated dentin surfaces. The amalgam cylinders have been exposed to a tensile bond test using a Universal Testing Machine (Instron 4500). ANOVA test has been used to the statistic study among groups. RESULTS: The study of the tensile mean range, showed that dentin shear bond strength values (MPa) for the adhesive systems tested were: 8.13 +/- 1.48 for AB2, 7.06 +/- 1.41 for SBMP, 4.2 +/- 1.06 for HQB, 3.04 +/- 0.68 for CL. The statistic test revealed significant differences among the 4 groups (p < 0.05). CONCLUSIONS: The bond strength mean values of amalgam adhesives are lower than the ones for composite resins, nevertheless dentin-enamel adhesive systems specific for amalgam have to be taken into consideration particularly in case of conservative restorations that need chemical retention as a support, when the mechanical one is not enough.