Asghar S, Ali A, Rashid S, Hussain T. J Coll Physicians Surg Pak Oct;20(10):

Transkript

1 Grupp 7 Sökuppgifter på Pubmed T3 frågor och svar 1. Vilken är den vanligaste orsaken till att en kompositfyllning måste göras om? Svara på frågan och klistra in ett abstract som stöder ditt svar. (Sök i MeSH. Komposit heter Composite resin och cytotoxiska reaktioner är icke önskade och den termen heter adverse effects) Svar. Vanliga orsaker till att dental kompositfyllningar måste göras om är sekundärkaries, missfärgningar och att fyllningen spricker. Svaret baseras på nedanstående artikel. Replacement of resin-based composite restorations in permanent teeth Asghar S, Ali A, Rashid S, Hussain T. J Coll Physicians Surg Pak Oct;20(10): OBJECTIVE: To determine the reasons for replacement of composite resin restorations and evaluate the association between the reasons for replacement of restorations with gender, duration of failure and different class of cavities. STUDY DESIGN: Cross-sectional study. PLACE AND DURATION OF STUDY: Operative Department of Fatima Jinnah Dental Hospital, Karachi, from January to May METHODOLOGY: Patients were selected randomly who had presented with post restoration complaint after composite filling. Specially designed proformas were used to get the information such as the name of the patient, age, gender, teeth in need for replacement of restorations, age of the replaced restorations, and the reasons for replacement. The criteria for replacement of composite restorations were secondary caries, discoloration, improper proximal contact, fractured restoration and gingival irritation due to overhang. The significance of results was obtained by applying chi-square test. RESULTS: A total of 413 patients ranging in age from 17 to 63 years were examined; 263 were males while 150 were females. Secondary caries (52.3%) was the most frequent reason for replacement of restorations in permanent teeth followed by discoloration (16.9%) and fracture of fillings (12.6%). Chi-square test shows significant relationship between gender and reasons for replacement (p < 0.001). Highly significant difference was found between different class of cavities and reasons for replacement of composite fillings (p < 0.001). The median longevity of the replaced composite restorations was about 3 years. CONCLUSION: Secondary caries was the most common reason for replacement of composite fillings. The median longevity in this sample was calculated to be 3.0 years. OK

2 2. Är det lämpligt att använda överskott vid gjutning (casting) av titan, vad säger litteraturen? Svara på frågan och klistra in ett abstract som stöder ditt svar. (sök i MeSH) Svar. De valde att göra ett test på detta. De testade 4 exemplar av varje material och valde att gjuta om det 7 gånger. Zink och tenn koncentrationen minskade betydligt mer vid omgjutning. Det visade också en ökning på Vickers hårdhet redan vid femte gången de hade gjutits. Ädel legering och nickel legering visade stor stabilitet efter att de gjutits om sju gånger. Men resultatet föreslår att inte använda om titan. Svaret baseras på nedanstående artikel. Effects of recasting on the chemical composition, microstructure, microhardness, and ion release of 3 dental casting alloys and titanium Peraire M, Martinez-Gomis J, Anglada JM, Bizar J, Salsench J, Gil FJ. Int J Prosthodont May- Jun;20(3): This study evaluated the effects of recasting on high noble, noble, and nickel-based alloys, as well as on titanium. Four specimens of each material were cast and recast 7 times. Chemical composition, microstructure, microhardness, and ion release were determined before and after the first cast and following each recast. Zinc and tin concentrations in the high noble alloy decreased significantly with recasting; consequently, the release of these ions decreased as well. A significant increase in Vickers hardness appeared in the fifth recast in both the high noble alloy and titanium. The noble alloy and the nickel-based alloy demonstrated great stability after 7 recasts. The results suggest not recasting titanium. OK 3. Påverkas färgen hos ett opakt porslin, bränt på olika legeringar (metal ceramic alloys), av flera bränningar? Svara på frågan och klistra in ett abstract som stöder ditt svar. (sök på MeSH dentala porslin, färg och MK-legeringar) Svar. Ja färgen påverkades efter tre och fyra bränningar. En oädel legering visade avsevärd större förändring än de övriga när den jämfördes med referensgruppen. Ädla metallegeringar hade mindre färgförändring av de övriga legeringarna, dessa förändringar var dock små och hade ingen klinisk påverkan. Svaret baseras på nedanstående artikel. Effect of repeated firings on the color of opaque porcelain applied on different dental alloys Yilmaz B, Ozçelik TB, Wee AG. J Prosthet Dent Jun;101(6): STATEMENT OF PROBLEM: Although metal ceramic fixed restorations are commonly preferred by clinicians, there remain a limited number of studies on how opaque porcelain color is affected by fabrication procedures, such as the number of firings and types of metal alloys.

3 PURPOSE: The purpose of this study was to determine the effects of various types of metal alloys on the color of opaque porcelain after repeated firings. MATERIAL AND METHODS: Seven different types of metal ceramic alloys (3 base metals: Metalloy CC, chromium cobalt (B-MCC); Heraenium NA, nickel chromium (B-HNA); Argeloy NP, nickel chromium beryllium (B-ANP); 3 noble metals: Ceradelta, palladium silver (N-CD); Cerapall 2, palladium (N-CP2); V-Delta SF, gold palladium (N-VDSF); and 1 high noble metal: V-Gnathos Plus, gold platinum (HN-GP)) were used to support a 0.1-mm-thick layer of opaque porcelain (IPS d.sign Opaquer, shade B1) to determine the metal alloys' effect on the opaque porcelain color after repeated porcelain firings. Opaque porcelain was applied on specimens (16 mm x 1 mm) prepared from each type of alloy. The specimens (n=21) were subjected to 1 opaque firing, 4 consecutive dentin firing cycles, and 1 glaze firing cycle. Delta E values were calculated for all metal alloy groups from opaque firing (control group) to each subsequent firing stage within each tested alloy group. One-way ANOVA and Fisher's least significant difference tests were performed to determine the differences between alloys. In addition, DeltaE values calculated after repeated firings were analyzed by 1-way ANOVA and paired t test, to determine whether repeated dentin firing stages affected the color of opaque porcelain (alpha=.05). RESULTS: After the first and second dentin firings, the color shift in opaque porcelain was significant for all tested alloy groups (P<.001). The color of opaque porcelain changed significantly after the third dentin firing for all groups except for B-HNA and N-VDSF (P<.001). After the fourth dentin firing, the color of opaque porcelain changed significantly for all tested alloy groups (P=.022 for B-ANP, P=.042 for N-VDSF, and P<.001 for remaining alloys). After glaze firing, the color change in opaque porcelain was significant in all but the N-CP2 group (P=.002 for N-VDSF, P=.014 for HN-GP, and P<.001 for remaining alloys). Delta E values showed that B-MCC after the first dentin firing, N-CD after the second dentin firing and glaze firing, and B-ANP after the third and fourth dentin firings showed significantly different DeltaE values than all remaining test alloys (P<.001). CONCLUSIONS: Subsequent porcelain firings significantly affected the color of a 0.1-mm-thick layer of opaque porcelain for all alloys tested. After the third and fourth firings, 1 base metal alloy (B-ANP) showed significantly greater color change than the remaining dental alloys when the color difference was compared to baseline. In addition, the color change in a noble alloy (N-CD) was significantly less than that of the other alloys after glaze firing. However, color shifts after repeated dentin firings were imperceptible (DeltaE<2.6) and clinically acceptable (DeltaE<5.5) for each type of alloy. OK 4. Kan bettskenor framställda i centralocklusionsläge ge lindring åt patienter med käkledsstörningar? Svara på frågan och klistra in ett abstract som stöder ditt svar (Sök på MeSH temporomandibular joint dysfunction syndrome + occlusal splint) Svar. Bettskenor framställda i centralocklusionsläge kan ge smärtlindring hos patienter med ocklusal stabilitet. Den ger ingen signifikant större smärtlindring än en vanlig bettskena men den är både lättare att tillverka och har ett lägre pris. Svaret baseras på nedanstående artikel.

4 Comparative evaluation of the efficacy of occlusal splints fabricated in centric relation or maximum intercuspation in temporomandibular disorders patients Hamata MM, Zuim PR, Garcia AR. J Appl Oral Sci Jan-Feb;17(1):32-8. Fabrication of occlusal splints in centric relation for temporomandibular disorders (TMD) patients is arguable, since this position has been defined for asymptomatic stomatognathic system. Thus, maximum intercuspation might be employed in patients with occlusal stability, eliminating the need for interocclusal records. This study compared occlusal splints fabricated in centric relation and maximum intercuspation in muscle pain reduction of TMD patients. Twenty patients with TMD of myogenous origin and bruxism were divided into 2 groups treated with splints in maximum intercuspation (I) or centric relation (II). Clinical, electrognathographic and electromyographic examinations were performed before and 3 months after therapy. Data were analyzed by the Student's t test. Differences at 5% level of probability were considered statistically significant. There was a remarkable reduction in pain symptomatology, without statistically significant differences (p>0.05) between the groups. There was mandibular repositioning during therapy, as demonstrated by the change in occlusal contacts on the splints. Electrognathographic examination demonstrated a significant increase in maximum left lateral movement for group I and right lateral movement for group II (p<0.05). There were no significant differences (p>0.05) in the electromyographic activities at rest after utilization of both splints. In conclusion, both occlusal splints were effective for pain control and presented similar action. The results suggest that maximum intercuspation may be used for fabrication of occlusal splints in patients with occlusal stability without large discrepancies between centric relation and maximum intercuspation. Moreover, this technique is simpler and less expensive. OK 5. Vilka ytkarakteristika hos ett material underlättar för biofilmbildning? Svara på frågan och klistra in ett abstract som stöder ditt svar (Sök på MeSH bacterial adhesion) Svar. Biofilm faster enklare på en ruggad yta än en slät. När väl en biofilm har börjat växa på t ex en guldlegering så ruggas materialet ytterligare och mer biofilm produceras. Svaret baseras på nedanstående artikel. Biofilm formation on dental restorative and implant materials Busscher HJ, Rinastiti M, Siswomihardjo W, van der Mei HC. J Dent Res Jul;89(7): Epub 2010 May 6. Biomaterials for the restoration of oral function are prone to biofilm formation, affecting oral health. Oral bacteria adhere to hydrophobic and hydrophilic surfaces, but due to fluctuating shear, little biofilm accumulates on hydrophobic surfaces in vivo. More biofilm accumulates on rough than on smooth surfaces. Oral biofilms mostly consist of multiple bacterial strains, but Candida species are found on acrylic dentures. Biofilms on gold and amalgam in vivo are thick and fully covering, but barely viable. Biofilms on ceramics are thin and highly viable. Biofilms on composites and glassionomer cements cause surface deterioration, which enhances biofilm formation again. Residual monomer release from composites influences biofilm growth in vitro, but effects in vivo are less pronounced, probably due to the large volume of saliva into which compounds are released and its continuous refreshment. Similarly, conflicting results have been reported on effects of fluoride release from glass-ionomer cements. Finally, biomaterial-associated infection of implants and devices

5 elsewhere in the body is compared with oral biofilm formation. Biomaterial modifications to discourage biofilm formation on implants and devices are critically discussed for possible applications in dentistry. It is concluded that, for dental applications, antimicrobial coatings killing bacteria upon contact are more promising than antimicrobial-releasing coatings. OK