Band and loop space maintainer--made easy

Space maintainers have been used in Pediatric Dentistry for many years. The use of these appliances, however, in terms of indications, contraindications, design and construction has gained little attention from researchers. This paper highlights the construction of a new technique of fabrication of band and loop space maintainer. The advantages of this new Direct technique or Single sitting technique over the conventional technique are discussed.     

Effect of operators' skills on increase in cavity volume of restorations.

OBJECTIVE: The purpose of this in vitro study was to evaluate the change in cavity volume after removal of amalgam and resin composite restorations, based on the dental skills of the operators. METHOD AND MATERIALS: A high-speed turbine and diamond burs were used to prepare Class II cavities in 60 acrylic resin mandibular first molar teeth. After the teeth were weighed with precision scales, the cavities were restored with amalgam or posterior resin composite. The restored teeth were then stored in distilled water at room temperature for 48 hours. Three undergraduate students with 2 years' practical experience on patients, and three postgraduate students with an additional 4 years' practical experience in the Department of Operative Dentistry, removed the restorations from the cavities with a high-speed turbine, and the teeth were all weighed again. After cavities were rerestored with the same materials, each restoration was removed once more by the same operator. The weighing procedure was repeated before and after the removal of the restorations. The data were subjected to paired and unpaired t tests. RESULTS: Every time a restoration was removed from a tooth, the cavity preparation became significantly larger, but the postgraduate students caused significantly smaller increases in cavity volume. CONCLUSION: Increases in cavity volume are not based on the nature of t he restorative material; however, the individual experience levelsand dental skills of the operators lead to significant differences in the cavity volume increase.     

The incidence of cysts and tumors around impacted third molars

The objective of this retrospective analysis was to determine the incidence of the development of cysts and tumors around third molars and to discuss some relevant issues in relation to the removal of asymptomatic, impacted third molars. 9994 impacted third molars, removed in 7582 patients, formed the basis of this study. The analysis revealed 231 cysts (2.31%) and 79 tumors (0.79%), including 7 benign tumors (0.77%) and two malignant tumors (0.02%). The incidence of cysts and tumors around impacted third molars was 3.10%.     

Composite autogenous bone and demineralized bone matrices used to repair defects in the parietal bone of rabbits

We compared the amount of new bone produced by endochondral and intramembranous autogenous bone grafts in the presence of demineralized bone matrices (DBMs) prepared from intramembranous bone (DBM(IM)) or endochondral bone (DBM(EC)). Thirty-five bone defects were created in the parietal bone of 20 New Zealand White rabbits. In the experimental groups, 5 defects were grafted with endochondral bone, 5 with endochondral bone mixed with DBM(IM)) (EC-DBM(IM)), 5 with intramembranous bone mixed with DBM(IM)(IM-DBM(IM)) and 6 with endochondral bone mixed with DBM(EC)(EC-DBM(EC)). In the control groups, 10 defects were left alone (passive control) and 4 were grafted with rabbit skin collagen (active control). They were all killed on day 14 and the defects were prepared for histological study. Serial sections were cut across the whole defect. Quantitative analyses were made on 202 sections of the experimental groups by image analysis. A total of 414%, 708%, and 85% more new bone was formed in defects grafted with composite EC-DBM(IM), IM-DBM(IM)and EC-DBM(EC), respectively, than those grafted with endochondral bone alone (P<0.001). No bone was formed in either passive or active controls. In conclusion, demineralized bone matrices, particularly those derived from intramembranous bone, have extremely high osteoinductive properties and greatly improve the integration of autogenous bone grafts in the skull.     

Effect of recombinant human platelet-derived growth factor-BB and bone morphogenetic protein-2 application to demineralized dentin on early periodontal ligament cell response

The purpose of this study is to investigate the early responses of human periodontal ligament cells attached to recombinant human platelet-derived growth factor-BB and bone morphogenetic protein-2 applied EDTA-demineralized dentin. One hundred and seventy-four root-planed flat dentin blocks were prepared from the mid-third of periodontally diseased human tooth roots. After demineralization with 24% EDTA (pH 7.02) 120 dentin blocks were treated with 0.5 and 1 microgram/ml rhPDGF-BB, 1 and 3 micrograms/ml rhBMP-2 and only MEM as control (24/group). Human periodontal ligament cells (HPLC) were seeded on these dentin surfaces and incubated. The alkaline phosphatase (ALP) activity and protein concentration of the attached cell were assessed at d 2, 4 and 7. Fifty-four dentin blocks were seeded with HPLC after application of 1 microgram/ml rhPDGF-BB, 3 micrograms/ml rhBMP-2 and MEM (18/group) and then incubated. At d 2, 4 and 7, the attached cells were stained and counted under light microscope. The results showed a significant increase of protein concentration and cell number in PDGF-BB treated groups than control (p < 0.05, p < 0.01) but not the ALP activity, and a significant increase of ALP activity was observed in BMP-2 treated groups than control (p < 0.05) but protein concentration and cell number remained almost the same over time. Thus, rhPDGF-BB and rhBMP-2 application to EDTA demineralized dentin surfaces promote the early human periodontal ligament cell responses by increasing cell proliferation and differentiation, respectively, which would ultimately enhance periodontal regeneration.     

Psychische Determinanten der Mitarbeit kieferorthopädischer Patienten — ein Beitrag zur Frage der Kooperationsprognose

Zusammenfassung In einer umfangreichen Untersuchung wurden Patienten, die nach Einschätzung ihrer Behandler in der kieferorthopädischen Behandlung besonders gut mitarbeiteten, solchen gegenübergestellt, die besonders schlecht mitarbeiteten. Dabei wurde ein psychodiagnostisches Instrumentarium verwendet, dessen Einzelverfahren so ausgewählt waren, daß sie sich für Kinder und Jugendliche eigneten und daß der erfaßte Inhalt etwas mit Kooperationsbereitschaft, Pflichteifer, Gewissenhaftigkeit und Ausdauer zu tun haben könnte. Es ergaben sich mehrere signifikante Unterschiede. Aufgrund der vorliegenden Ergebnisse kann der Typ des nichtkooperativen Patienten beschrieben werden.

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Summary A large scale study was conducted in which orthodontic patients, who were rated as highly cooperative in treatment were compared to uncooperative patients. The specific psychological diagnostic tests were chosen to be suitable for children and adolescents and to reflect cooperation, responsibility, reliability and endurance. A number of significant differences could be found. The results enable one to describe the type of uncooperative patient.

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Résumé Dans une étude approfondie, on a comparé lors de leur traitement orthodontique, des patients qui ont été particulièrement coopératifs avec ceux qui l'étaient moins. Pour cela, on a utilisé un procédé diagnostique psychologique, choisi pour être adaptable aux enfants et aux adolescents et dont l'analyse reflète la coopération, le zèle, la responsabilité et la persévérance. Il en résulte plusieurs différences significatives. Il permet aussi de décrire le type du patient non-coopératif.

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Vortrag, gehalten auf der Jahrestagung der Deutschen Gesellschaft für Kieferorthopädie 1985 in Mainz.     

Tissue localization of Actinobacillus actinomycetemcomitans in human periodontitis. I. Light, immunofluorescence and electron microscopic studies

Invasion of periodontal tissues by different bacterial morphotypes has been reported in human periodontitis; however, limited information is available as to prevalence, localization and the bacterial species involved. The present study determined prevalence and gingival localization of Actinobacillus (Haemophilus) actinomycetemcomitans in periodontal lesions of juvenile periodontitis patients. Thirty-five gingival biopsies were obtained from 12 juvenile periodontitis patients at the time of periodontal therapy. One additional control biopsy was obtained from each of two adult periodontally healthy subjects, one adult periodontitis patient and one periodontally healthy monkey (Macaca fosibolius). The biopsies were carefully processed to avoid mechanical introduction of bacteria into the tissues and were examined using light and electron microscopy. Rabbit antisera specific for the three A. actinomycetemcomitans serotypes were used for immunofluorescence microscopic localization of A. actinomycetemcomitans antigens in the gingival sections. Immunofluorescence microscopy showed A. actinomycetemcomitans specific antigens in the gingival tissues of 11 of the 12 juvenile patients examined. None of the control specimens showed evidence of A. actinomycetemcomitans antigens in the gingival connective tissue. One specimen from a periodontally healthy subject and the monkey biopsy, however, showed A. actinomycetemcomitans antigens in bacterial plaque on the surface of the crevicular epithelium. Transmission electron microscopic examination showed microcolonies of small gram-negative rods in the connective tissue, as well as single bacterial cells between collagen fibers and in areas of cell debris. In addition to these extracellular bacterial cells, evidence of bacterial cells was also found within gingival connective tissue phagocytic cells. The data from the present study suggest that the gingival tissue in juvenile periodontitis lesions harbors A. actinomycetemcomitans.     

Effects of in-office bleaching products on surface finish of tooth-colored restorations

A number of "high power" in-office bleaching products have recently been re-introduced into the market. The use of such strong oxidizing agents has raised questions as to possible adverse effects on tooth structure and restorative materials. This study evaluated the effects of 35% carbamide peroxide (Opalescence Quick) and 35% hydrogen peroxide (Opalescence Xtra) on the surface finish of four tooth-colored restorative materials (Spectrum TPH, Dyract AP, Reactmer and Fuji II LC). Twenty-seven matrix-finished specimens of each material were fabricated, stored in distilled water at 37 degrees C for seven days and randomly divided into three groups. Specimens in Group 1 were stored in distilled water at 37 degrees C (control). Specimens in Groups 2 and 3 were treated with 35% carbamide peroxide and 35% hydrogen peroxide, respectively. A total of three 30-minute bleaching sessions were conducted at one-week intervals. Storage medium during the hiatus period was distilled water at 37 degrees C. Surface roughness measurements were carried out using profilometry after each bleaching session. Data was analyzed using ANOVA/Scheffe's test at a 0.05 significance level. No significant difference in surface roughness was observed between the bleached and the control groups for all materials. In-office bleaching products are not detrimental to the surface finish of composites, compomers, giomers and resin-modified glass ionomer cements.     

Effects of surface finish on indentation modulus and hardness of dental composite restoratives.

OBJECTIVES: The depth-sensing micro-indentation testing was recently introduced for the characterization of dental composites. One of the critical issues raised was the possible influence of surface finish on material properties. The aim of this study was to investigate the effects of surface finish on the indentation modulus and micro-hardness of resin-based dental composite materials. METHODS: The materials used included minifill (Z100, 3M ESPE), microfill (A110, 3M ESPE) and poly-acid modified (F2000, 3M ESPE) composites. The specimens were polished successively using SiC grinding papers of different grit size and diamond suspensions to achieve varying surface roughness. The arithmetic mean of the roughness (R(a)) was measured using profilometry. In the depth-sensing micro-indentation test, specimens (n=7) were indented to 10N with Vickers indenter and the load-displacement (P-h) data was obtained using a universal testing system. The indentation modulus (E(in)) and hardness (H) were then computed using the developed analytical solutions. Data was analyzed using ANOVA/post-hoc Scheffe's test at significance level 0.05. RESULTS: The polished specimens had surface roughness ranging from 0.02 to 0.81 microm. The roughness of F2000 was significantly higher than A110 and Z100. The E(in) and H for Z100 ranged from 14.02 to 14.83GPa and 1.18 to 1.27 GPa, respectively. E(in) for F2000 and A110 ranged from 12.25 to 13.82 GPa and 5.26 to 5.52 GPa and hardness ranged from 0.89 to 0.98 GPa and 0.52 to 0.55 GPa, respectively. SIGNIFICANCE: The indentation modulus and hardness of dental composite restoratives were independent of the surface finish provided indenter penetration is sufficiently deep (h(max)/R(a)>30).