Ali Kemal Ozdemir

Shear Bond Strength of Resin Cement to Zirconia Ceramic After Aluminum Oxide Sandblasting and Various Laser Treatments

OBJECTIVE The aim of this study was to evaluate the effect of different surface treatments; sandblasting, Er:YAG, Nd:YAG, or CO(2) laser irradiation on the shear bond strength (SBS) of zirconia ceramic to dentin. BACKGROUND DATA Zirconia is not properly luted with resin cements. Various surface treatment methods have been suggested for zirconia to obtain high bond strength to resin cements. There is no study that compared the effect of different laser types (Er:YAG, Nd:YAG, CO(2)) with sandblasting on SBS between zirconia and dentin. METHODS One hundred and twenty human maxillary third molar teeth were sectioned 3 mm below the occlusal surfaces, embedded in a metal ring with autopolymerizing acrylic resin, and stored in distilled water at 37(0)C. One hundred and twenty disc-shaped zirconia specimens were fabricated (6 mm in diameter and 4 mm in thickness), and randomly assigned to six groups (n=20): Group 1, untreated (control); Group 2, sandblasted; Group 3, Er:YAG laser irradiated; Group 4, Nd:YAG laser irradiated with contact; Group 5, Nd:YAG laser irradiated with non-contact; Group 6, CO(2) laser irradiated. They were cemented onto the dentin with dual-cured resin cement (Variolink(®)). After they were stored in distilled water at 37(0)C for 24 h, the SBS test was performed at a crosshead speed of 1 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. RESULTS Results of this study did not show statistically significant differences between Groups 1 and 2, or among Groups 3, 4 and 5. The lowest SBS was recorded in Group 6 (CO(2) laser), and the highest SBS was recorded in Group 4 (Nd:YAG laser with contact), followed by Group 3 (Er:YAG laser). The adhesive failure mode was predominantly observed in Groups 2, 3, 5, and 6. Group 1 showed 45% mixed failure and Group 4 showed 50% mixed failure. CONCLUSIONS This study shows that Er:YAG and Nd:YAG laser treatment increased the bond strength of zirconia compared to sandbasting and CO(2) laser treatment.

Shear Bond Strength of Veneering Ceramic to Zirconia Core After Different Surface Treatments

OBJECTIVE The aim of this study was to evaluate the effect of different surface treatments: sandblasting, liners, and different laser irradiations on shear bond strength (SBS) of pre-sintered zirconia to veneer ceramic. BACKGROUND DATA The SBS between veneering porcelain and zirconium oxide (ZrO2) substructure was weak. Various surface treatment methods have been suggested for zirconia to obtain high bond strength to veneering porcelain. There is no study that evaluated the bond strength between veneering porcelain and the different surface treatments on pre-sintered ZrO2 substructure. METHODS Two hundred specimens with 7 mm diameter and 3 mm height pre-sintered zirconia blocks were fabricated. Specimens were randomly divided into 10 groups (n=20) according to surface treatments applied. Group C, untreated (Control); Group E, erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiated; Group N, neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiated; Group SB, sandblasted; Group L, liner applied; Group NL, Nd:YAG laser irradiated+liner applied; Group EL, Er:YAG laser irradiated+liner applied; Group SN, sandblasted+Nd:YAG laser irradiated; Group SE, sandblasted+Er:YAG laser irradiated; and Group SL, sandblasted+liner applied. The disks were then veneered with veneering porcelain. Before the experiment, specimens were steeped in 37°C distilled water for 24 h. All specimens were thermocycled for 5000 cycles between 5°C and 55°C with a 30 sec dwell time. Shear bond strength test was performed at a crosshead speed of 1 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. RESULTS Surface treatments significantly changing the topography of the yttrium-stabilized tetragonal zirconia (Y-TZP) ceramic according to scanning electron microscopic (SEM) images. The highest mean bond strength value was obtained in Group SE, and the lowest bond strength value was observed in NL group. Bond strength values of the other groups were similar to each other. CONCLUSIONS This study shows that sandblasting+Er:YAG, sandblasting, Er:YAG+liner, sandblasting+Nd:YAG, and Er:YAG laser treatment on pre-sintered ZrO2 substructure increased the bond strength to veneering porcelain, compared with other surface treatments. After different surface treatments, there was no difference in surface roughness of pre-sintered zirconia to compare after sintering; sintering enhanced the bond strength within the limitations of present study.

Porselen ile titanyumun bağlanma dayanımına Nd-YAG lazerin etkinliğinin incelenmesi

Objectives:To investigate bond strengthbetween Estenia, is a kind of seromer has beenincreasingly used in dentistry, low fusing porcelainand titanium metal sub-structures after differentsurface treatments.Materials and Methods: In the present study,ISO9693:1999 standards 25x3x0.5mmdimensionsof the samples used prepared with titanium in themetal substructure. Metal sample surface blasting(n=12) and Nd-YAG laser with a blasting + laser(n=12) by application of the working groups wereformed. Low-temperature materials as porcelainsuperstructure estenia seromer group size 8x3x3mmmetal substructure to be appliedaccording to the instructions of the manufacturer.Later examples, universal testing device todetermine the three-point transverse fractureresistance test was performed. Unit load applicationrate of 0.5 mm/min and the distance between thejaws adjusted to 20 mm. Example of porcelainmetal sub-structure, divided into groups, the type ofthe current connection N/mmstrength values wererecorded. Mann-Whitney U test was used for theevaluation of the data obtained.Results: Titanium metal sub-structures in termsof strength of connection estenia materialdetermined to be sufficient, can be a seriousalternative to high temperature porcelains weredetected. However, the Nd: YAG laser irradiationof titanium surface connection valueswere determined in a value increase, but statistically notsignificant.Conclusion:Blasting and sandblasting +samples compared to laser therapy, sand blasting +laser groups showed no statistically significantdifferences in terms of connection strength.(p>0.05).

Mandibular tam protez ölçü modellerinin üç boyutlu bir ölçüm yöntemiyle karşılaştırılması

Amac: Bu cal man n amacmandibular alveolar kret olculerinin stabilitesinin uc boyutlu bir olcum yontemiyle de erlendirilmesidir. Gerec ve Yontem: Bu cal mada 14 di siz hastadan al nan olculer kullan ld . Hastalar iki gruba ayr ld . Son olcu maddesi olarak birinci grupta cinko-oksid ojenol (ZOE), ikinci grupta polivinilsiloksan (PVS) kullan larak al nan olculerden ana modeller elde edildi. Ana modeller uzerinden modifiye ahsi ka k haz rlanarak hastalardan olcu alc s ile yeniden olculer al nd . Elde edilen modeller uzerinde s n r cizgileri tahmini olarak cizildi ve alveol kret uzerinde 14 referans noktas belirlendi. Ana modellerin foto raflar al nd (Nikon E2/E2s) ve 3 boyutlu goruntuleri elde edildi. Alveolar kret yuksekli i, protezin oturdu u alan n buyuklu u ve cevresel s n r cizgilerinin uzunlu u 3 boyutlu goruntuler uzerinde olculdu. Bulgular: Bu cal mada olcu alc s yla elde edilen modellerdeki olcum de erlerinin di erlerinden yuksek oldu u goruldu. Olcu alc s yla bundan du uk de erlerde olcum de erleri gosteren cinko-oksid ojenol olcu modelleri aras nda istatistiksel olarak anlamlbulunamad (p>0.05). Buna kar l k polivinilsiloksan ile elde edilen modellerin olcum de erlerinde alveolar kret yuksekli i istatistiksel olarak anlaml bir azalma gosterdi (p< 0.05). Sonuc: Olcu maddesinin alveolar mukoz membran uzerindeki etkileri membran n ozelliklerine ve ahsi ka k dizayn na ba lkalmaktad r. Bu yuzden desteksiz reziduel kretlere sahip mandibular tam protez hastalar nda olcu maddesinin ve olcu tekni inin secimi oldukca onemlidir. Mandibular tam protez olculerinin olcu alc s ve cinko-oksid ojenol olcu maddesi ile al nmas onerilmektedir

Tumour necrosis factor α and interleukin-1β levels in three premature neonates with respiratory distress syndrome

Sir: Cytokine production capacity in the neonatal period has not been well documented, although studies have given contradictory results showing decreased or normal tumour necrosis factor (TNF) and interleukin-1 (1L-l) levels in comparison with healthy adults [1, 2, 5, 8]. TNF-c~ and IL-I~ are important mediators of host defence that are released mainly from monocytes/macrophages and T-lymphocytes in response to endotoxin, tissue injury and anoxia [8]. Respiratory distress syndrome (RDS) of the newborn is associated with a significam pulmonary inflammatory reaction. More neutrophils and alveolar macrophages are found in lung effluent fluid of preterm infants with pulmonary disease caused by surfactant deficiency than in the fluid of healthy newborn subjects [4]. In our previous study [6], we investigated the levels of serum TNF-c~, IL-1 and IL-6 in neonatal sepsis. Besides healthy newborns, there were also thre e premature babies with RDS in our control group (Table 1), Those infants were excluded from the analysis after high levels of cytokines were detected in their sera. The interesting result was that the two premature infants who later died had markedly elevated serum TNF-a and IL-I~3 levels on admission (case A and B). The one who survived had normal serum TNF-a and mildly elevated IL-1 ~ levels (case C). None of them showed any signs of infection during their follow up period in the nursery, t t igh levels of TNF-c~ and IL-I ~, detected in two premature infants who did not survive were thought to be related to the severity of their illness and high degree of tissue injury or anoxia. We have found few studies on cytokine levels in neonatal RDS. Groneck et al. [3] determined the effects of dexamethasone (early or late treatment) on chemotactic activity and inflammatory mediators. They reported 16 premature infants with RDS out of 21 patients (who were ventilated for a long time) had elevated chemotactic activity, neutrophils, IL-I~, leukotriene B4 and arproteinase inhibitor levels in tracheal aspirate fluids. They noted that an inflammatory reaction was present in the lungs of infants of with RDS at risk for chronic lung disease and that the release of inflammatory mediators and influx of neutrophils into the airways were reduced by early treatment of dexamethasone. Stefano et al. [7] compared plasma and tracheal aspirate soluble IL-2 receptor (sIL-2R) levels in bronchopulmonary dysplasia and RDS. They found higher plasma sIL-2R levels in bronchopulmonary dysplasia than in RDS or control groups. Miller et al. [5] reported that IL-1 ~3, but not TNF and IL-6 levels were elevated and that levels corresponded to the type of delivery and the severity of non-infectious perinatal complications. In conclusion, further investigations are necessary in order to clarify the possible role of cytokines in the pathogenesis and prognosis of this disease. References