Involvement of PTCH gene in various noninflammatory cysts.

Constitutional hemizygous inactivation of PTCH, the Shh signaling pathway gene that moderates the signal, manifests itself as nevoid basal cell carcinoma syndrome or Gorlin syndrome, a condition variably characterized by a number of developmental disorders and malformations, and by predisposition to some malignancies, basal cell carcinoma in particular. Loss of heterozygosity for the PTCH region was found several years ago in the epithelial lining of odontogenic keratocysts, the cyst type with highly increased incidence in nevoid basal cell carcinoma syndrome. This finding confirmed the expectations that the gene responsible for the syndrome would have a decisive role in the genesis of these cysts even when they are not syndrome related. Suggestive temporal distribution of Shh signaling, recently observed during tooth development, lead us to investigate PTCH association with dentigerous cysts, the other major noninflammatory cyst of odontogenic origin. We report here that PTCH appears to be inactivated in dentigerous cysts, suggesting that it is responsible for their genesis as well. More generally, if our similar observations of incomplete heterozygosity in this region for dermoid cysts can be interpreted as loss of heterozygosity, PTCH alterations may prove to be a necessary, and perhaps the initiating event, in formation and growth of various noninflammatory cysts. This would be consistent with our view that local PTCH inactivation can, under favorable circumstances, lead to persistent though not by itself truly aggressive cell proliferation.

Suppression of salivary Streptococcus mutans and lactobacilli by topical caries preventive agents.

Reduction of cariogenic bacteria, especially salivary Streptococcus mutans and lactobacilli is a valuable clinical procedure that in many ways alleviates implementation of targeted caries preventive procedures in the entire population. The aim of this study was to investigate the caries preventive values of certain preventive procedures in in vivo conditions. Four groups of subjects, each with 18 children aged from 4-5 and 10-12 years (n = 72) were treated with different caries preventive agent (aminfluoride solution, Proxyt paste, chewing gum containing xylitol and fluoride and chlorhexidine solution). During a period of two months five control measurements for number of salivary Streptococcus mutans (SM) and lactobacilli (LB) were performed. At the end of the study the best result in the reduction of the bacteria was achieved by the application of Proxyt paste and daily use of chewing gum (p < 0.001). In patients treated with this preventive procedure the number of SM was reduced by 1 class and LB to < 10(4) CFU/ml saliva after two months of study. The results obtained indicate that professional teeth cleaning and use of chewing gum with xylitol and fluorides on daily basis can be very effective protocol for cariogenic bacteria reduction and in the individual caries prevention.

Histologic difference in epithelial linings between follicular and radicular cysts.

The purpose of this study was to identify histologic differences in epithelial linings between follicular and radicular cysts in relation of their development. Linings and surrounding tissues of 25 radicular and 20 follicular cysts from archival paraffin embedded tissues were obtained and stained with haematoxylin and eosin. Radicular cysts showed orthokeratotic 9-14 cell-layer-thick non-keratinized squamous epithelium and unspecific chronic inflammatory reaction in connective tissue. Follicular cysts showed 2-4 cell-layer-thick of non-keratinized stratified squamous or flattened-low cuboidal epithelium and connective tissue capsule free from inflammatory cell infiltration.

Evaluation of sporadic cases of odontogenic keratocysts in multicentric study.

The aim of this retrospective study was to report frequency of sporadic odontogenic keratocysts (sOKC) according to the age and gender, as well as location (mandible, maxilla, soft tissues, and maxillary sinus). Four hundred and twenty nine sOKC confirmed pathohistologically in a period from 1965-1998 were included in this study. The average age of patients with sOKC was 43.11 (age range 10-91), in males 42.06 and in females 44.72 years. More frequently sOKC were found in males (60.61%) in comparison to the females (39.39%). Therefore, ratio between males and females was 1.5:1. Diagnosis of sOKC is usually established in patients aged 21-30 (18.88%), in males usually aged between 21-30 (23.46%), and in females aged between 11-20 (18.93%). sOKC are more frequent in males according to the age groups, except between age 61-70 where sOKC were more frequent in females. Most frequently, sOKC occurred in the mandible 70.16%, 12.35% of sOKC were found in the maxilla, 12.82% in soft tissues and 4.66% in the maxillary sinuses.

[Possibility of the application of CO2 laser in the prevention of demineralisation of the enamel]. / Mogucnost primjene CO2 lasera u prevenciji demineralizacije cakline.

Tooth enamel laser irradiated under certain conditions previously has been shown to have reduced subsurface demineralizations rate. The teeth were cut vertically in half with a thin diamond disc. One half of each tooth served as a control and the other half was irradiated using the CO2 laser. Laser energy was applied at incisive labial surface (15 W, 0.5 s, spot size 3.5 mm). After irradiation the specimens were coated with wax leaving only the windows 3 x 3 mm on the labial surfaces. After experimental demineralisation with 0.2 M sodium acetate and 0.1 M lactic acid solution for 10 days, dissolved calcium and phosphorus were analyzed in the demineralizating solutions using atomic absorption spectrophotometry and colorimetric method (method described by Lowey), respectively. Ca and P concentrations in demineralizing solutions per unit surface area were lower then the controls.

[Composite retention area produced by CO2 laser beam]. / Priprema retencijske povrsine za kompozitni ispun pomocu CO2 lasera.

Laser effect on enamel is manifested as consequence of temperature changes. Enamel melts, vaporises and a crater, and fissures are formed. Retention surface for anchoring of composite resin was obtained in intact approximal surfaces of premolars with CO2 laser (0.5, 1 and 3 W, sport size 1 and 1.5 mm, 0.2 and 0.5 s). The study results reveal composite and lased enamel interfaces are stronger then composite and inlased enamel (p less than 0.01) but weaker than composite and acid pretreated enamel interface (p less than 0.01).

In vitro pulp chamber temperature rises associated with the argon laser polymerization of composite resin.

STUDY DESIGN/MATERIALS AND METHODS: This in vitro study was performed upon 50 extracted human molars that provided the occlusal surfaces for standard class I preparations. The cavity floor of the 20 specimens was covered with zinc phosphate cement and the teeth were sectioned transversally at or below the cementoenamel junction. In some specimens pulp tissue was removed from the pulp chamber. The cavities of all specimens were filled with composite resin, and the resin was cured with an argon laser. RESULTS: A statistically significant difference in the rise in temperature was obtained only in the temperature of dentin roof of the pulp chamber between the specimens with (2.2 degrees C) and without (3.1 degrees C) cement base (P < .05). There was no significant difference in the temperature of the pulp tissue between specimens with (2.7 degrees C) and without (2.2 degrees C) base cement. The peak temperature of the composite surface was 13.8 degrees C. CONCLUSION: These data indicate that argon laser curing may be a method of choice for polymerization of the composite resin.

[Residual caries and prosthetic treatment]. / Rezidualni karijes i zubi u protetskoj obradi.

The aim of this study was to assess the extent to which residual caries causing pulpal lesions may affect the prosthetic treatment success. Two hundred and twenty-three teeth were observed prior to prosthetic grinding and 15 months after the prosthetic appliance cementation. Study subjects were divided into three groups: group I consisting of 75 intact teeth, group II including 95 teeth where old fillings were removed, and group III with 53 teeth where old fillings were not removed prior to grinding for prosthetic treatment. Results showed pulp to be affected by disease in 24 or 10.76% of cases in total. Intact teeth were affected in 5 or 6.67% of cases, and those with replaced fillings in 8 or 8.24% of cases. These results were statistically significant (P greater than 0.05). Differences in pulp damage between the group with removed fillings and that where the existing fillings were not removed, and between the group where fillings were not removed and that of intact teeth, were statistically significant (P less than 0.05), suggesting that undetected residual caries under old fillings should be added to the known and described causes leading to failure of prosthetic dental treatment. Therefore, it appears quite desirable to replace old fillings prior to prosthetic treatment of the teeth.

[The antimicrobial efficiency of aqueous solutions of calcium hydroxide on Streptococcus mutans, Streptococcus faecalis and Candida albicans, in vitro]. / Antimikrobni ucinak vodenih pripravaka kalcijevog hidroksida na Streptococcus mutans, Sterptococcus faecalis i Candida albicans, in vitro.

Calcium hydroxide preparations Ca(OH)2 are used as water solutions, putly, liner, cement or artificial material. The therapeutic effect of each medicaments depends on physical and chemical characteristic of additional components. The aim of the paper is to research the sensitivity of Streptococcus faecalis and Candida albicans to different water solution concentrations of calcium hydroxide. As solid plates, Bacto-Mitis-Salivarius agar was used for S. mutans, Torlak blood agar for S. faecalis and Sabourand agar "Torlak" for C. albicans. The holes were drilled in solid plates and were filled by 0.2 ml of water solutions of Ca(OH)2. Preparations, created as described were incubated aerobically at 37 degrees C in the period of 48 hrs. Results were read after 24 as well as after 48 hrs. The examined solutions of Ca(OH)2, revealed the highest antimicrobic effect after 24 hrs. The result remained unchanged even after 48 hrs. The inhibition of S. mutans growth on the solid plate occurred with the concentration of Ca(OH)2 solution from 271.18 x 10(-2) mol/dm3 and pH 12.76. The growth of S. faecalis at the solid plate was inhibited with the concentration of 3335.21 x 10(-3) mol/dm3 and pH 12.82. The inhibition of C. albicans growth on solid plate occurred with the concentration of Ca(OH)2 solution from 1023.20 x 10(-3) mol/dm3 and pH 12.84. The difference in the sensitivity of the examined microorganisms at the same concentrations of Ca(OH)2 solution was observed.

PTCH gene altered in dentigerous cysts.

Motivated by the evidence that odontogenic keratocysts are associated with genetic alterations, we examined the possibility that development of other odontogenic cysts can be attributed to gene malfunctioning, in particular to the PTCH gene. Cyst epithelium was examined for polymorphism on chromosome 9q22.3, the region that contains the PTCH gene. Loss of heterozygosity (LOH) for the D9S287 marker and/or D9S180 marker was observed in about 50% of dentigerous cysts, whereas radicular cysts gave no indication of lesions in the PTCH region. As a more direct argument for PTCH involvement in cystic growth, we report evidence of PTCH expression in dentigerous cyst lining, which indicates malfunctioning of the relevant signaling pathway. While we found no reason to believe that PTCH should be associated with radicular cysts, other genes may be implicated in their development. We performed immunohistochemical comparisons of keratocysts, dentigerous and radicular cysts for the nonmetastatic marker Nm23. A graded response placed radicular cysts in between the other two types, suggesting a similar neoplastic character for their epithelial proliferation.

Involvement of patched (PTCH) gene in Gorlin syndrome and related disorders: three family cases.

AIM: To find genetic alterations in PTC or other genes of the Shh/PTCH pathway in tumorous and non- tumorous samples from three families and to correlate them with the varying expression of disorders in presented nevoid basal cell carcinoma syndrome (NBCCS) phenotypes. METHOD: DNA was extracted from archival paraffin-embedded tissues, tumor tissue or peripheral blood leukocytes, and the loss of heterozygosity (LOH) and single strand conformational polymorphism analysis was performed using PCR with primers for polymorphic 9q22.3 markers (D9S196, D9S287, D9S180, D9S127); PTCH exons 3, 6, 8, 13, 15, 16; and smo (smoothened) exon 1. G-banding tecnique was used for cytogenetic analysis of the peripheral blood lymphocytes. RESULTS: We found a LOH for PTCH in several cases and variability in smo in one case. In one case NBCCS could reasonably be ascribed to hemizygous PTCH inactivation, while in other two families this typical correlation between the syndrome phenotype and the observed genetic alterations could not been established. CONCLUSIONS: Further analysis of relatively sparse cases of NBCCS is needed before the symptoms of the syndrome could be convincingly explained by genetic alterations in the Shh/PTCH signalling pathway.