Biomechanical demands of percussive techniques in the context of early stone toolmaking.

Recent discoveries in archaeology and palaeoanthropology highlight that stone tool knapping could have emerged first within the genera Australopithecus or Kenyanthropus rather than Homo. To explore the implications of this hypothesis determining the physical demands and motor control needed for performing the percussive movements during the oldest stone toolmaking technology (i.e. Lomekwian) would help. We analysed the joint angle patterns and muscle activity of a knapping expert using three stone tool replication techniques: unipolar flaking on the passive hammer (PH), bipolar (BP) flaking on the anvil, and multidirectional and multifacial flaking with free hand (FH). PH presents high levels of activity for Biceps brachii and wrist extensors and flexors. By contrast, BP and FH are characterized by high solicitation of forearm pronation. The synergy analyses depict a high muscular and kinematic coordination. Whereas the muscle pattern is very close between the techniques, the kinematic pattern is more variable, especially for PH. FH displays better muscle coordination and conversely lesser joint angle coordination. These observations suggest that the transition from anvil and hammer to freehand knapping techniques in early hominins would have been made possible by the acquisition of a behavioural repertoire producing an evolutionary advantage that gradually would have been beneficial for stone tool production.

Relationship between unintentional canal overfilling and the long-term outcome of primary root canal treatments and nonsurgical retreatments: a retrospective radiographic assessment.

AIM: To determine retrospectively the long-term radiographic outcome of root canal treatments and root canal retreatments with unintentional root canal overfilling. METHODOLOGY: A total of 220 root canal treatments (143 primary/77 retreatments) with postoperative unintentional canal overfilling and performed by two endodontists during their 45 years of private practice were included in the study. Lateral condensation techniques and nine different sealers were used. Overfilling was confirmed with a postoperative periapical radiograph and patients were scheduled regularly for recall visits. Average recall time was 4.86 years (maximum = 30 years). Two calibrated observers evaluated the radiographs and determined the long-term outcome using the PAI score pooled in a 3-category scale. The persistence or resorption of the extruded material was registered. The Kappa coefficient (K) was calculated and a logistic regression was used for further analysis. Odds ratios and their 95% CI were estimated. RESULTS: The level of inter-observer agreement was 66.1%. Primary root canal treatments had a significantly (P = 0.015) greater rate of success (91.6%) than retreatments (81.8%). Tooth location (P = 0.019) was the only other factor that significantly affected the outcome. The type of extruded material, and its resorption or persistence did not relate to the outcome. Persistence of extruded material was significantly affected by tooth location and recall time after treatment. CONCLUSION: The outcome of root canal treatment with unintentional canal overfilling was not associated with the type of extruded material or its resorption or persistence. The persistence of extruded material did not relate to a favourable or unfavourable outcome.

Effect of photopolymerization variables on composite hardness.

STATEMENT OF PROBLEM: Variations in light-polymerizing parameters, such as light intensity and light-to-material distance, may affect the physical characteristics of polymerized resin. PURPOSE: The purpose of this study was to characterize the relation between total light energy and the final hardness of 4 composites polymerized under varying conditions. MATERIAL AND METHODS: Four commercial composite restorative resins (Z100, Filtek A110, Tetric Ceram, and Tetric Flow) were used to prepare 4 disk-shaped specimens (6 x 2 mm) for each experimental condition. Photoactivation was carried out with a light device and energy of 22.6, 15.7, 9.0, or 6.7 J/cm(2). Either the light-to-material distance (0, 5, 10, 15 mm) or activation time (40, 28, 16, 12 seconds) was varied. Immediately after polymerization, Barcol hardness was determined on the specimen surface that had been exposed to the light. Analysis of variance (P<.05) and regression analysis were used to examine the data. RESULTS: No significance (P>.05) was found for the overall effect of the experimental variables (polymerization time and distance), but significant differences (P<.01) were found among materials and energy levels. Regression equations for each product and polymerization condition were calculated for hardness as a function of energy. No significant differences were found for slopes within each material. Hardness values were 3.0 to 3.5 for Tetric Ceram, Tetric Flow, and Filtek A110 and approximately 4.9 for Z100. CONCLUSION: The hardness of the products analyzed was related to the total energy used for activation. The effect was independent of the manner in which the amount of energy was modified (light-to-material distance or activation time).

Barcoll hardness of dental materials treated with an APF foam.

The hardness of a dental material is generally related to its mechanical properties. The purpose of this study was to evaluate the hardness of several resins and cements exposed to an APF Foam (Minute Foam, Oral-B). Four molds 6 x 2 mm were prepared for each experimental condition with each of the following materials: Filtek P 60 (3 M); Silux Plus (3 M); Ariston pHc (Vivadent); F 2000 (3 M); Vitremer Restorative (3 M) and lonofil Molar (Voco). Immediately after prepared, the samples were stored in water or in the APF foam. To evaluate the Barcoll hardness, measurements were made on both sides of the specimens (top--T and bottom--B), immediately, and after 1 min, 24 h and 7 d. The results, expressed as percentages of the loss of hardness of each sample from the baseline readings, were analyzed with an ANOVA and Tukey's test. ANOVA revealed the significant influence of material, time and treatment. The surface analyzed (T or B) had no significance. Among the glass-ionomers tested the loss of hardness was significantly higher (+30%) than for resin-based composites (+/- 15%). Treatment with the APF foam for 7 days produced the greatest loss of hardness (42%) and at 24 h the least (less than 5%). There were no other significant findings. It can be concluded that the effect of the APF foam is material dependent, but is significantly more pronounced with the glass-ionomers than the resins tested. The application time of the foam is the main factor for the loss of hardness.

Adhesion of composite to air-abraded enamel and dentin.

The purpose of this study was to compare the shear bond strength of a resin composite to air abraded and not air abraded enamel and dentin surfaces, and to evaluate the need for acid conditioning before the application of a single component adhesive. Enamel (E) and dentin (D) flat surfaces were obtained from a pool of recently extracted human teeth (30 incisors and 30 molars) and prepared with different treatments with and without the application of air abrasion (AA) and phosphoric acid (PA). Composite samples were bonded to the surfaces and stored in distilled water at 37 degrees C. After 24 hours, shear bond strength tests were carried out with an Instron machine and the results were subjected to statistical analysis. Maximum bond strength was obtained in the E + AA + PA group (34.74 MPa--2.70), followed by: E + PA (31.26 MPa--1.87); D + PA (24.09-1.72); D + AA + PA (20.61 MPa--1.79); D + AA (8.96 MPa--0.82) and E + AA (7.17 MPa--1.75). The results were significantly lower in those groups that were not acid conditioned (P < 0.01). The bond strength of composite to enamel was slightly increased as a result of the combination of AA with PA. However, the opposite effect was observed on dentin surfaces. Acid etching is a necessary clinical step even on air abraded surfaces.

Adhesion of composite to air-abraded enamel and dentin

The purpose of this study was to compare the shear bond strength of a resin composite to air abraded and not air abraded enamel and dentin surfaces, and to evaluate the need for acid conditioning before the application of a single component adhesive. Enamel (E) and dentin (D) flat surfaces were obtained from a pool of recently extracted human teeth (30 incisors and 30 molars) and prepared with different treatments with and without the application of air abrasion (AA) and phosphoric acid (PA). Composite samples were bonded to the surfaces and stored in distilled water at 37 degrees C. After 24 hours, shear bond strength tests were carried out with an Instron machine and the results were subjected to statistical analysis. Maximum bond strength was obtained in the E + AA + PA group (34.74 MPa--2.70), followed by: E + PA (31.26 MPa--1.87); D + PA (24.09-1.72); D + AA + PA (20.61 MPa--1.79); D + AA (8.96 MPa--0.82) and E + AA (7.17 MPa--1.75). The results were significantly lower in those groups that were not acid conditioned (P < 0.01). The bond strength of composite to enamel was slightly increased as a result of the combination of AA with PA. However, the opposite effect was observed on dentin surfaces. Acid etching is a necessary clinical step even on air abraded surfaces.

Adhesion of composite to air-abraded enamel and dentin.

The purpose of this study was to compare the shear bond strength of a resin composite to air abraded and not air abraded enamel and dentin surfaces, and to evaluate the need for acid conditioning before the application of a single component adhesive. Enamel (E) and dentin (D) flat surfaces were obtained from a pool of recently extracted human teeth (30 incisors and 30 molars) and prepared with different treatments with and without the application of air abrasion (AA) and phosphoric acid (PA). Composite samples were bonded to the surfaces and stored in distilled water at 37 degrees C. After 24 hours, shear bond strength tests were carried out with an Instron machine and the results were subjected to statistical analysis. Maximum bond strength was obtained in the E + AA + PA group (34.74 MPa--2.70), followed by: E + PA (31.26 MPa--1.87); D + PA (24.09-1.72); D + AA + PA (20.61 MPa--1.79); D + AA (8.96 MPa--0.82) and E + AA (7.17 MPa--1.75). The results were significantly lower in those groups that were not acid conditioned (P < 0.01). The bond strength of composite to enamel was slightly increased as a result of the combination of AA with PA. However, the opposite effect was observed on dentin surfaces. Acid etching is a necessary clinical step even on air abraded surfaces.

Evaporation of solvent in one-bottle adhesives.

OBJECTIVE: To compare the evaporation of vehicles included in different single-bottle adhesives as a function of time. METHODS: The following adhesives were used: Prime and Bond 2.1 (Dentsply); Single Bond (3M); PrimaBond 97' (BJM); Syntac Sprint (Vivadent); Optibond Solo (Kerr) and Syntac Single Component (Vivadent). Two primers that are used in multiple-component adhesives (PermaQuick Primer, Ultradent and Scotchbond Multipurpose Primer, 3M) as well as distilled water, 96% ethanol and acetone were also included in the experiment. Samples of these products were stored in small glass containers under controlled temperature and humidity conditions. Initials mass and mass after different periods of time were registered to calculate the percentage loss of mass. RESULTS: The analysis of variance of the results followed by orthogonal contrast comparisons revealed a significantly higher loss of mass in the single-bottle adhesives that contain organic vehicles (especially in those in which the vehicle was acetone). A somewhat lower loss of mass was found in a water-based product. CONCLUSION: There is a relationship among the evaporation possibilities of the vehicles used in single-bottle adhesive systems and their loss of mass during storage.

Solubility and fluoride release in ionomers and compomers.

OBJECTIVE: The degree of solubility and the fluoride release of glass-ionomer cements and "compomers" were determined as a function of time. METHOD AND MATERIALS: Three conventional glass-ionomer cements, three hybrid ionomers, and two compomers were included in the study. Disk-shaped specimens were prepared and immersed in a lactic acid solution. Solubility was evaluated from determinations of loss of mass as a function of time. To evaluate fluoride release, similar specimens were immersed in 50 mL of deionized water to which 50 mL of buffer solution was added. A fluoride ion detector was used to read the concentration of fluoride ion in the overall solution at different times after immersion. RESULTS: Material and time factors had a significant influence on results. The compomers showed less corrosion and fluoride release than the ionomers. Some correlation was found between solubility and fluoride leakage values. CONCLUSION: Components of both the ionomers and compomers that were studied can dissolve in water. The materials leak fluoride ions in amounts that differ according to the characteristics of the individual products.

Antimicrobial effect of six endodontic sealers: an in vitro evaluation.

The aim of this study was to determine the in vitro antimicrobial effect of six endodontic sealers after 2, 20 and 40 days. The sealers studied were Apexit, Endion, AH26, AH-Plus. Procosol and Ketac Endo. The microorganisms used were Candida albicans, Staphylococcus aureus, Streptococcus mutans and Actinomyces israelii. Petri dishes were filled with sterile agar and 0.1-ml wells were prepared and filled with the sealers. The agar plates were stored for 24 h at 37 degrees C. The samples were then removed, immersed in 4.5 ml of culture medium and divided into three groups. The samples in group 1 were stored for 2 days at 37 degrees C whereas the samples of groups 2 and 3 were stored at 4 degrees C for 20 and 40 days respectively. The samples were then removed and discarded, and 0.1 ml of the culture medium was seeded on the agar plates in order to perform colony forming unit counts. Apexit, Endion and AH-Plus produced slight inhibition on Streptococcus mutans at 20 days and on Actinomyces israelii at every time interval. No effect was found on Candida albicans and Staphylococcus aureus. Ketac Endo only produced an antimicrobial effect on Actinomyces israelii at 2 and 40 days. AH26 and Procosol showed antimicrobial effect at 40 days on Candida albicans, at 20 and 40 days on Streptococcus mutans and Staphylococcus aureus, and an effective inhibition on Actinomyces israelii at every time interval. Statistical analysis revealed both sealers and microorganisms to be significant factors affecting results in groups 2 and 3. In conclusion, the sealers evaluated in this study showed different inhibitory effects depending on time span. Overall, sealers containing cugenol and formaldehyde proved to be most effective against the microorganisms at the time intervals studied.

Adhesion of a compomer to dental structures.

The objective of this study was to evaluate the bond strength of a compomer to dental enamel, dentin, and cementum. Flat surfaces of these tissues were obtained from recently extracted human teeth. The different substrates were either treated with PSA (a primer and adhesive) or acid etched (35% phosphoric acid gel) and treated with PSA. Cylindrical specimens of compomer were then bonded to the substrates. Shear bond strength was determined after a 24-hour immersion in 37 degrees C water. Significant differences were found between both treatments on enamel, while none were found on dentin or cementum. The use of acid etchant on enamel as a surface-conditioning step previous to priming with PSA allowed a better bond between Dyract compomer and that substrate; acid etching was not particularly needed on dentin and cementum.

Disintegration of endodontic cements in water.

The disintegration of three endodontic cements in water was determined quantitatively and qualitatively. The materials studied were Ketac-Endo (KE), Tubli Seal (TS), and AH26 (AH). Specimens were immersed in water for 48 h (GI), 7 (GII) and 45 days (GIII). The solid residue was then determined. For the qualitative analysis three groups of tubes were filled with the materials and stored in water for the same periods. The exposed surface was photographed. Results expressed as percentage of original mass in the quantitative analysis for loss of mass due to dissolution were: GI = KE 2.39 (0.70); TS 3.56 (0.37); AH 4.94 (2.83); GII = KE 2.84 (0.30); TS 2.50 (0.50); AH 0.66 (0.26); GIII = KE 1.60 (0.84); TS 1.03 (0.42); AH 1.22 (0.54). Tukey's least significant difference (0.05) was 2.94. In the qualitative experiment KE disintegration was far more evident than that suffered by other materials. The quantitative results had no correlation with the qualitative observations probably due to the difference in the moment when the materials were immersed.

Barcoll hardness of resin-modified glass-ionomer cements and a compomer.

The objective of this study was to evaluate the influence of several factors on the hardness of resin-modified glass-ionomer cements (hybrid ionomers) and polyacid-modified resin composites (compomers). Disk-shaped specimens were prepared from the following materials: Vitremer, Fuji II LC, Photac-Fil, and Dyract. Three specimens of each product were irradiated with a light-curing device and three were not. Barcoll hardness was determined on both sides of the specimen 10 minutes after irradiation and after 48 hours of immersion in 37 degrees C water. A factorial design was used to evaluate the factors that influenced the results. The Dyract group that was not light cured was not included in the analysis because the product did not harden under this circumstance. Analysis of variance revealed a significant effect of material, time, and specimen side when light curing was carried out. The use or nonuse of light curing was also significant. For some hybrid ionomers (e.g., Photac-Fil), light curing is a more essential step than for others to obtain adequate hardness values.

Prolonged treatment of chronic C hepatitis by means of medium-high doses of recombinant alpha-2b interferon: an open study to evaluate response and long-term relapse.

Thirty-six patients with hepatitis C virus-RNA positive chronic hepatitis were studied to evaluate whether recombinant alpha-2b interferon, in medium-high doses, (6-9 MU 3 times/week) over a long period (12-18 months), was more effective in reducing or normalizing alanine aminotransferase values, and in reducing the relapsing percentage than the historical trials. At the end of the 12th and 18th month of treatment, mean alanine aminotransferase values were significantly reduced; the level of complete responses was 36.1%, at the end of the 12th month, and 19.4% at the end of the 18th month (intention to treat). These results were no better than comparable findings in the literature. At the end of the first follow-up (12th month), percent complete responses fell to 15.5%, with a relapse rate of 14.3%. At the end of the second follow-up (24th month), percent complete responses fell further to 11.1% (all 4 patients with a 24 months sustained response showed absence of viraemia), with a relapse rate of 42.9%; even these percentages were judged unsatisfactory. In conclusion, no significant advantage was obtained by prolonging interferon treatment and/or using higher dosages. However, the possible virus clearance in all the long-term responders seems to justify further investigation in terms of cost-benefit analysis.

Germicide effect of several glass ionomer cements.

One the most significant characteristics of glass ionomer cements is their ability to release fluoride compounds. This study was carried out to try establish relationships between this property and the possible effect on the growth of microorganisms that are found in carious lesions, Agar BHI medium containing Petri dishes were flooded with strains of Actinomyces naeslundii, Actinomyces israelii and Actinomyces odontolyticus. Cavities were then prepared in the agar and filled with mixtures of several glass ionomer cements. Some of them were polymerizable resin containing products. A zinc phosphate and a zinc oxide-eugenol cement were used as controls. After a seven day incubation at 37 degrees C under anaerobic conditions the inhibition halos around the specimens were measured in a way similar to that used for antibiograms. The statistical analysis of the results showed no significant differences among Actinomyces strains but a significant difference one among cements. Even when no definitive conclusions could be drawn it is worth taking into consideration the effect of glass ionomer cements on microorganisms such as the Actinomyces and continuing studies to establish more clearly what is required from the material to produce a clinically significant outcome.

Shear bond strength of adhesive composite systems to human dentin.

This study was carried out to evaluate the following adhesive systems under different conditions from the point of view of the bond strength that is obtained on dentin: Scotchbond Multipurpose, 3M: Denthesive II, Kulzer; Optibond, Kerr with techniques # 1 and 5; and A.R.T. Bond. Coltene. Composite resin (Z100, 3M) cylindrical specimens were bonded to flat dentin surfaces and the adhesive strength was determined under shear. No significant differences were found between the group in which products were used with a separate step of dentin demineralization and the group in which this step is not recommended or was omitted. It can be concluded that the use of dentin acid treatment as a separate step is not necessarily required for high composite bond strength even when it could represent a convenient clinical step to prepare enamel surfaces simultaneously.

[Psychological and psychopathological correlates in Dupuytren's disease]. / Correlati psicologici e psicopatologici nel morbo di Dupuytren.

The etiology of Dupuytren's disease, a chronic and depressive lesion of the palmar aponeurosis, is still unclear. Numerous factors have been implicated, including psychopathological elements and a stressor psychosomatic response, possibly in the presence of a personality structure which may represent a diathesis. On the other hand, from a psychosomatic point of view, any psychic correlates could be secondary to somatic damage. In order to look for common psychological and psychopathological elements in the syndrome 39 patients were examined by a team of orthopedics specialised in hand surgery during the period 1990-91. All cases were studied by clinical interview, the evaluation of anamnestic data of possible psychiatric importance and the use of Rorschach and MMPI tests. The data obtained do not confirm that specific personality elements or psychopathological factors can be correlated to the clinical symptoms of Dupuytren's disease given that the results are comparable to what may be considered the characteristics of a non-selected but age- and culturally-matched population. There are only sporadic findings indicating neurotic and depressive factors, or senile involution. Likewise, no reliable and uniform stressing events were observed, or particular signs of maladaptation related to environmental reactivity or the disease itself.

Treatment of autonomous thyroid nodules with percutaneous ethanol injection: 4-year experience.

PURPOSE: To evaluate the long-term efficacy of treatment of autonomous thyroid nodules with percutaneous ethanol injection under ultrasound guidance. MATERIALS AND METHODS: Treatment was performed in 101 patients. The mean ratio of injected ethanol volume to nodule volume was approximately 1.5; ethanol was usually administered in four to eight sessions. RESULTS: Complete cure was achieved in 59 patients. Partial cure was achieved in 34 patients. Eight patients had remission of thyrotoxicosis but persistence of thyroid-stimulating hormone level suppression and radionuclide uptake only in the nodule. The extent of the response was inversely proportional to the nodule volume. Marked nodule shrinkage was observed in all groups. No recurrences were observed. Transient vocal cord paresis occurred in four patients, with full recovery in all cases. CONCLUSION: This method compares favorably with both surgery and radioiodine treatment, especially when the very low prevalence of posttreatment hypothyroidism is considered.

The evaluation of fine-needle procedures for the diagnosis of focal liver lesions in cirrhosis.

To evaluate the diagnostic accuracy of fine-needle aspiration, fine-needle biopsy and extranodular fine needle biopsy in identifying focal lesions in cirrhosis, 100 consecutive ultrasound detected nodules were studied. Seventy-three were hepatocellular carcinomas (31 were well-differentiated hepatocellular carcinomas), 23 were benign lesions (one angioma and 22 large regenerative nodules) and two were metastases. The lesions were divided according to maximum diameter as follows: < 20 mm in 36, > 20 < 30 mm in 27, and > 30 mm in 33. In four cases there were multiple nodules of different sizes. Fine needle aspiration, intranodular fine needle biopsy and extranodular fine needle biopsy were obtained in each lesion. The sensitivity, specificity and diagnostic accuracy of each procedure were evaluated separately by three independent pathologists. Seven fine needle aspirations and three intranodular fine needle biopsies were considered inadequate. The highest diagnostic accuracy (96%) was obtained by the combined analysis of fine needle aspiration plus intranodular and extranodular fine needle biopsy, and this superiority was confirmed in each group of lesions. Fine needle aspiration showed a lower accuracy (48%) than intranodular fine needle biopsy (67%). When fine needle aspiration and intranodular fine needle biopsy were evaluated together, an accuracy of 91% was found. Intralesional fine needle biopsy plus extranodular fine needle biopsy analysis gave an accuracy of 78% and, particularly relevant, a specificity of 95%. These results indicate that, in patients with cirrhosis with nodular lesions < 30 mm, fine needle biopsy is superior to fine needle aspiration and that the combined evaluation of fine needle aspiration plus intranodular and extranodular fine needle biopsy is the most accurate approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Antimicrobial power of composite resin adhesion systems.

The adherence of microorganisms to dentin that had been contaminated and then treated with conditioning substances was evaluated. The germicide effect of those products and their possible substantivity was also evaluated. Dentin slices were contaminated with Candida albicans, Streptococcus mutans and Actinomyces naeslundii and then treated with the following substances: 1. Experimental Blue Solution A, 2. Experimental Red Solution B; 3 Tubulicid Blue Label; 4. Tubulicid Red Label; 5 Scotchprep Dentin Primer; 6 ventura Dentin Bond Cleaner; 7 ventura Dentin Bond Primer, 8. Gluma dentin Bond; 9 Tenure Conditioner; 10. All Bond Dentin Conditioner; 11 Syntac Primer; 12. Clearfil New Bond acid + adhesive; 13 Prisma Universal Bond 3 Primer; 14. Denthesive Cleaner; 15. Control (Distilled water). Adherence was evaluated using scanning electron microscopy and viability tests were performed. Substances 1, 2, 3, 4, 5, 7, 8, and 11 impair adherence; the control and substances 6 and 9 produced no afforded intermediate results effect while substances 10, 12, 13 and 14. Viability tests afforded results similar to those obtained for adherence. Several substances that are used for dentin treatment or for dentin priming for adhesion could be useful in preventing microorganism viability and so contribute to the protection of pulp vitality.