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Biomedical subjects

J P Rocca

Publications and source records attributed to J P Rocca.

At least 19 recordsLinked to original sources
PubMed2004

External temperature during KTP-Nd:YAG laser irradiation in root canals: an in vitro study.

To avoid the damage of periodontal tissues during laser irradiation of the root canal, the conditions of lasering must be carefully controlled. The aim of this study was to determine the safety parameters of the irradiation conditions during the use of a KTP-Nd:YAG laser in root canals. Root canals of 60 freshly extracted teeth were prepared (step-back technique) and filled with a photosensitiser (Acid Red 52). Different irradiation conditions [output power (P), pulse width (PW), pulse repetition rate (PRR, Hz)] were used. The laser beam was delivered by means of the KTP-Nd:YAG fibre tip with a beam spot-size diameter of 200 microm. The temperature increases were measured on the external apical third of the root surface using a thermocouple. The results showed that the temperature rise was always below 7 degrees C at the following laser settings: (1) single irradiation, P < or = 4 W, PW < or = 2.55 ms and PRR < or = 20 Hz; (2) repetitive irradiation series, five pulses of 1 s each, four resting times of 1 s each, P < or = 2.25 W, PW < or = 2.55 ms and PRR < or = 20 Hz. The use of resting times was necessary so as to avoid thermal cumulative effects. In these in vitro irradiation conditions, the use of the KTP-Nd:YAG laser in endodontics may be considered harmless for periodontal tissues.

Dental Pulp Cavity↗
PubMed2002

Periapical status, prevalence and quality of endodontic treatment in an adult French population.

AIM: The aim of this study was to determine the periapical status and the quality of root-canal treatment amongst an adult population attending the dental school in Nice, France during 1998. METHODOLOGY: Patients who attended the dental school for the first time during 1998 were included. Panoramic radiographs, taken by a trained radiology assistant, were used in this study. The periapical areas of all teeth with the exception of third molars, were examined and the technical quality of root fillings were evaluated for both apical extension and density. Statistical analyses were conducted using anova, Chi-square, Fisher's PLSD and Cohen's Kappa tests. RESULTS: The survey involved 344 patients: 180 females and 164 males. Males had significantly fewer natural remaining teeth than females (P<0.03). Similarly, the average number of root-filled teeth was lower for males (P<0.01). Nonroot-filled teeth (n=6126) had significantly fewer signs of periapical pathology than root-filled teeth (n=1429) (1.7% vs. 31.5%, P<0.0001). The majority of root fillings were poorly executed. There was a significant correlation between the presence of periapical pathology and inadequate root-canal fillings (P<0.001). CONCLUSIONS: The results of the present study indicate that many root-canal treatments were technically unsatisfactory in terms of quality and treatment outcome. There is a need for endodontic retreatment in the population examined.

Adult↗
PubMed1999

The removal of the smear layer using the Quantec system. A study using the scanning electron microscope.

AIM: The aim of this study was to determine the ability of the Quantec Series 2000 rotary nickel-titanium endodontic system to remove dentinal debris and smear layer produced during canal preparation. METHODOLOGY: A first group (control) of 12 curved root canals was prepared using conventional manual instruments and the step-back technique. A second group of 12 curved root canals was instrumented using the complete Quantec sequence according to the manufacturer's instructions. In both groups, irrigation was performed using a 3% NaOCl solution. The canal walls were observed under a scanning electron microscope and the coronal, middle and apical thirds of each canal photographed at a magnification of 500. The views were divided into 10 subareas by overlaying a grid, and the absence or presence of a smear layer was rated and scored on three appearances using the scale described by Ciucchi et al. (1989). RESULTS: The scores were higher (i.e. less debris was present) in the middle third (P < 0.0001) and in the apical third (P < 0.0001) of canals prepared with the Quantec system when compared with those prepared with K-files. Nevertheless, in canals prepared with Quantec instruments, the scores were significantly higher in the coronal third compared with the apical third (P < 0.005). CONCLUSIONS: The Quantec rotary system produced cleaner canal walls than conventional manual instrumentation, particularly in the middle and apical thirds. This finding may imply that stresses applied to the cutting regions of Quantec instruments by accumulation and compression of the smear layer are minimized.

Dental High-Speed Technique↗
PubMed1998

Antimicrobial activity of amalgams, alloys and their elements and phases.

OBJECTIVES: This in vitro study aimed to evaluate the antibacterial effect of amalgams, alloys, elements and phases against two cariogenic bacteria, Actinomyces viscosus and Streptococcus mutans. METHODS: Test materials comprised: (i) commercial amalgams comprising Amalcap (Vivadent), Cavex Avalloy LC and DP (Cavex), Cupromuc (Merz), Fluoralloy and Synalloy (Dentoria); (ii) Ag-Cu alloy; (iii) gamma, gamma 1, gamma 2 and Cu6Sn5 phases; (iv) pure metal samples and chloride solutions of copper, mercury, tin and zinc; and (v) aqueous sodium fluoride. Bacterial suspensions of each of the two bacteria were grown in the presence of the test materials for 24 h. Antimicrobial effectiveness was assessed by measuring reduction in optical density at 640 nm using a visible spectrophotometer. RESULTS: Cupromuc/Fluoralloy, non gamma 2 amalgams and Amalcap displayed high, moderate and no antibacterial activity, respectively. Antibacterial effectiveness was not related to copper content. Whereas mercury, copper, Ag-Cu alloy, fluoride and zinc showed antibacterial activity (Hg > Cu > F > Zn), tin, gamma phases and Cu6Sn5 showed no such activity. SIGNIFICANCE: Although the fluoride and copper solutions were most effective at 50 micrograms ml-1 concentration, their antibacterial action was still significant, albeit reduced, at 10 micrograms ml-1 concentration. This was not the case for mercury chloride which was just as effective at both concentrations. Our results show that although mercury and copper contribute significantly to the antibacterial properties of amalgams, a high copper content does not necessarily relate to high antibacterial effectiveness. These elements could be useful in conferring antibacterial properties to amalgam although their effects on host cells must be investigated.

Actinomyces viscosus↗
PubMed1998

Experimental single controlled study of burned bones: contribution of scanning electron microscopy.

Burned bones were studied using Scanning Electron Microscopy. The samples were cut from a maxillary-mandibular block taken during an autopsy. These fragments were heated in a furnace under controlled temperature conditions for 60 minutes. The temperatures ranged from 150 to 1150 degrees Celsius. The results are as following: (i) there are significant alterations of the bone, more and more obvious as the temperature increases, (ii) it appears to be difficult to establish a precise correlation between the temperature and the scanning electron microscopy patterns.

Aged↗
PubMed1998

Macroscopic and microscopic aspects of incinerated teeth.

Fifty-eight premolars, extracted for orthodontic reasons, were incinerated for one hour in a furnace at temperatures varying from 150 degrees C to 1150 degrees C, increasing at 100 degrees C intervals. Between 150 degrees C and 700 degrees C the teeth changed from light yellow to bluish-white passing through brown. The scanning electron microscope showed that at 150 degrees C cracks appeared in the enamel, increasing in number as the temperature rose. At 450 degrees C the internal surface detached from the dentine and showed the same cracked surface as the exterior. Above 1100 degrees C the enamel fragments had a prismatic structure difficult to identify due to their melted structure. Dentine retained its tubular structure up to 1150 degrees C even when the tubules' diameter decreased at 700 degrees C. The cementum cracked as the temperature increased. Certain cracked areas actually detached at 600 degrees C giving a corroded aspect to the cementum and the residual zones became irregular when the temperature rose and eventually at 1150 degrees C the cementum was no longer identifiable.

Adolescent↗
PubMed1997

Removal of Thermafil root canal filling material.

The aim of this study was to evaluate if removal of Thermafil plastic carriers and reestablishment of working length were possible in single rooted teeth filled with the Thermafil system. Twenty freshly extracted maxillary central incisors were prepared and filled with #30 Thermafil plastic obturators according to manufacturer's recommendations. Teeth were divided in two groups: Group I: 10 teeth were retreated using dimethylformamide as a solvent. Group II: 10 teeth were retreated using chloroform as a solvent. Removal of filling material was performed manually using K files and H files alternately between carrier and dentinal walls. The average time needed to remove the plastic carrier was 7 min for group I and approximately 6 1/2 min for group II. No deformation of the plastic carrier was observed after removal from the canal. Removal of plastic carriers and measurement of the proper working length were easily performed using manual endodontic instruments. Chloroform greatly enhanced this procedure.

Chloroform↗
PubMed1994

Removal of calcified attached denticle with a pulsed dye laser. A case report.

This article presents the removal of an attached pulp denticle with the use of a pulsed dye laser. The quartz fiber was introduced in the root canal and placed in direct contact with the free border of the denticle. Thirty-two pulses were necessary to fragment the pulp stone. A scanning electron-microscopic study shows a sharp section at the base of the pulp stone.

Dental Pulp Calcification↗
PubMed1993

An investigation into the use of restriction endonuclease analysis for the study of transmission of Actinomyces.

DNA fingerprints of 28 reference strains of Actinomyces, comprising representatives of different species and serotypes, and 19 isolates recovered from 16 periodontal patients was performed. The aim was to determine the potential of the method for detecting strain differences in terms of discriminatory power and to evaluate its usefulness in the typing of Actinomyces strains for eco-epidemiological studies. Among the 17 restriction endonucleases tested, Bst EII, Pvu II and Sma I proved to be the most suitable for the genus Actinomyces restriction digest analysis. Visual comparisons of Bst EII, Pvu II and Sma I digest patterns of chromosomal DNA revealed clear differences within species but also within serotypes of Actinomyces that are otherwise identical. The method offers the qualities for use as an epidemiological tool for identifying sources and tracing routes of transmission of Actinomyces: stability, reproducibility, ease of preparation and interpretation and enough sensitivity for detection of differences between morphologically and serologically similar strains of Actinomyces.

Actinomyces↗
PubMed1993

[Comparison of the cleansing effect of two micromotor-driven endodontic hand pieces. I. Comparison ot the cleansing effect of the two handpieces].

The aim of the study was to assess the cleansing-effect of two endodontic handpieces (Excalibur, W & H; MM 1400 Micro Méga) in root canals that were previously manually prepared, and treated with chlor-(Neomagnol) and citric acid containing solutions. The analyses were performed by scanning electron microscope (SEM). The elimination of the Smear Layer (SL) with Neomagnol was not successful with either of the two handpieces. The cleansing of the Superficial Debris (SD) with Neomagnol activated by MM 1400 was significantly more effective in the apical (p < 0.05) and in the middle (p < 0.01) third of the root-canal, than by Excalibur. In contrast, SL was better eliminated by Excalibur using citric acid, significant differences--when compared with MM 1400--could be seen in the middle third (p < 0.05) of the root-canal. The handpieces seem to have their own specific characteristics: thus MM 1400 was better in eliminating the SD (used with Neomagnol), while Excalibur was superior in eliminating the SL (used with citric acid).

Dental Instruments↗
PubMed1993

[Cleansing effect of two micromotor-driven endodontic handpieces.II. Effect of various rinsing solutions on the cleansing effect of the handpieces].

The cleansing effectivity of citric acid solution was significantly better than that of Neomagnol both with respect to the removal of the Smear Layer (SL) and to the number of visible dentinal tubular orifices, however a complete elimination of the SL could not be obtained. Neomagnol seemed to be more effective in the removal of superficial debris and tissue-remnants.

Chloramines↗
PubMed1991

[Effect of local anesthetics on the dental pulp. Study in rats].

According to the in vitro and in vivo procedures described by Rockert and Pracros, the effect of different local anesthetics (with and without vaso-constrictive solution) have been studied on rat incisor dental pulp. Histological analysis (optical microscopy) of samples (90 rat incisors) showed: A systematic pulp response with concentrations up to 2%. This response correspond with a toxic reaction on the respiratory activity of pulp cells; A highest response with solutions containing a vaso-constrictor additive; An increasing response according to the nature of the anesthetic solution.

4-Aminobenzoic Acid↗
PubMed1989

Antibacterial properties of five dental amalgams: an in vitro study.

The antibacterial activity of five commercially available amalgams (Cupromuc, Dispersalloy, Fluoralloy, Predalloy, and Synalloy) against two bacterial species frequently isolated from dental plaque and caries (Actinomyces viscosus and Streptococcus mutans) was studied by use of a modification of the method of Orstavik (1985). All amalgams displayed some antibacterial properties. This antibacterial activity was amalgam- and bacteria-dependent. Cupromuc and Fluoralloy were the most active, and the non-gamma 2 amalgams showed intermediate activity. Combined with mechanical and biological properties, these differences should be taken into account when one is choosing an amalgam for clinical use.

Actinomyces↗