Bahadir Ersu

Surface roughness and bond strengths of glass-infiltrated alumina-ceramics prepared using various surface treatments

OBJECTIVES To compare and evaluate effects of CO(2) laser and conventional surface treatments on surface roughness and shear bond strengths of glass-infiltrated alumina-ceramics to dentin. METHODS One hundred fifty ceramic discs of In-Ceram Spinell, In-Ceram Alumina and In-Ceram Zirconia (n=50) were prepared. Specimens which were divided into 5 groups (n=10) were untreated (control group), sandblasted, airborne particle abraded, etched with 9.6% hydrofluoric acid or irradiated with CO(2) laser. Scanning electron microscope was used at 1000x magnification for qualitative examination. Following surface roughness (Ra) determination by profilometry, discs were cemented on extracted-human-molar teeth. Cemented specimens were stored in distilled water at 37 degrees C for 1 week. Shear bond strength (MPa) test was performed using a universal testing machine at a crosshead speed of 1mm/min. Statistical comparisons were made with Wilcoxon signed ranked test, Kruskall Wallis test and Spearmans correlation coefficient. RESULTS All surface treatments produced rougher surfaces than the untreated groups of all ceramics (P<.05). Sandblasting demonstrated a rougher surface on In-Ceram Spinell than In-Ceram Alumina and In-Ceram Zirconia (P<.05). While CO(2) laser irradiation showed significantly higher bond strength for In-Ceram Spinell (P<.05), both airborne particle abrasion and CO(2) laser irradiation showed higher bond strengths for In-Ceram Zirconia (P<.05). Airborne particle abrasion demonstrated higher bond strength for In-Ceram Alumina and In-Ceram Zirconia (P<.05). No significant relationship was determined between surface roughness (Ra) and shear bond strength values (MPa) among ceramic groups. CONCLUSIONS Sandblasting is an effective surface treatment for roughening surfaces of In-Ceram Spinell. Although CO(2) laser irradiation does not increase surface roughness, it reveals the highest bond strength.

High dose rate mold brachytherapy of early gingival carcinoma: A clinical report

Two elderly edentulous patients with the diagnosis of early stage cancer of the upper gingiva were treated by customized dental mold brachytherapy. Locoregional tumor control was achieved in both patients. One patient is alive without any evidence of disease 36 months after treatment, the other patient died of distant metastasis shortly after brachytherapy. Brachytherapy, being easy to apply with short treatment time and good acute tolerance, is a good choice and effective modality for the management of early stage gingival cancer, particularly in elderly patients.

Laser gas‐assisted nitriding of Ti implant

Purpose – The purpose of this paper is to investigate the morphological and metallurgical changes of laser gas‐assisted nitriding of titanium implants.Design/methodology/approach – Laser gas‐assisted nitriding of titanium implant is carried out and the metallurgical as well as the morphological changes in the nitride layer are examined using optical microscopy, SEM, XRD, and X‐ray photoelectron spectroscopy. Temperature and thermal stress fields are computed during the laser heating process adopting the finite element method. The residual stress formed in the nitride layer is measured using the XRD technique while micro‐indentation tests are carried out to determine the fracture toughness of the surface after the laser treatment process.Findings – It is found that nitride depth layer extends to 40 μm below the surface and it is free from the cracks and micro‐voids. The residual stress formed on the surface region is higher than at some depth below the surface in the nitride layer, provided that the maximu...

Attaching a midfacial prosthesis to eyeglass frames using a precision attachment

aResearch Assistant, Department of Prosthodontics, Faculty of Dentistry, Gazi University. bAssistant Professor, Department of Prosthodontics, Faculty of Dentistry, Hacettepe University. (J Prosthet Dent 2009;102:264-265) This article describes a procedure for attaching a midfacial prosthesis to eyeglass frames using a precision attachment. The advantages of this technique are that the patient is able to remove the eyeglasses without removing the prosthesis, and the degree of retention can be controlled. Retention of midfacial prostheses has traditionally been provided with adhesives, anatomic undercuts, or connection to eyeglasses.1 Problems commonly encountered with these methods of retention have been reported.2-5 Respiratory epithelium is easily traumatized by frictional contact with the prosthesis and limits the use of anatomic undercuts. Soft tissues around midfacial defects may not be ideal for adhesive retention, because movements that occur with facial expressions compromise adaptation of the prosthesis margin.5 The use of craniofacial implants for retention of extraoral prostheses can provide excellent support and retention and improve a patient’s quality of life.6,7 However, placement of craniofacial implants for extraoral prosthetic rehabilitation in patients with abnormal bone and soft tissue anatomy as a result of extensive ablative tumor surgery is a challenge for surgeons. Also, the use of implants may be limited or delayed by radiotherapy, chemotherapy, and/or the patient’s health status.8 Eyeglasses can be effectively used to retain a nasal prosthesis when other means are not available. If the eyeglasses have thick, opaque frames, they help to camouflage the prosthesis margins. If retention is provided to a midfacial prosthesis using eyeglass frames, it is necessary to permanently attach the prosthesis to the eyeglasses. The disadvantage of attaching the nasal prosthesis to the eyeglass frames is that, when the eyeglasses are removed, the prosthesis is also removed, which can be embarrassing to the patient.1 The objective of the technique described is to provide retention to a midfacial prosthesis using eyeglasses without permanently attaching the prosthesis to the eyeglass frames. The advantage of this technique is that the connection between the eyeglasses and prosthesis is provided by a precision attachment system; therefore, the patient is able to remove the eyeglasses without removing the prosthesis. Also, the amount of retention of this attachment can be controlled.

Periauricular mold brachytherapy

PURPOSE We present a patient with recurrent basal cell carcinoma (BCCA) who was treated with custom-made mold brachytherapy. METHODS AND MATERIALS The patient was admitted to the hospital with the complaint of recurrent BCCA of the auditory canal. He has previously treated by surgery and external beam radiotherapy. We decided to continue with reirradiation to tumor bed after surgical excision. A total of 25 Gy to 5mm depth of surgical bed was delivered by mold brachytherapy. RESULTS The patient did well during the treatment without any acute toxicity. He was lost to followup after 2 years of treatment without any obvious late morbidity. CONCLUSION Custom-made mold brachytherapy is an alternative treatment modality, for reirradiation of selected group of patients, with minimal morbidity and good disease control.

The Fracture Resistance of Composite Core Materials Reinforced by Varying Fiber Orientations.

This study aimed to compare the fracture resistance of composite core materials reinforced with varying fiber orientations. Composite cores of endodontically treated roots were prepared by reinforcing with woven fiber discs, fiber strips, or fiber chips, and their fracture resistance was compared to those with no reinforcement using a universal test machine (Instron, Lloyd Instruments). Reinforcement with fiber chips showed the highest fracture resistance and 50% retrievability, while no reinforcement showed the lowest fracture resistance with 62.5% retrievability. It can be concluded that the use of fiber chips may be an effective and practical method for reinforcement of the core material.

Effect of engraving speeds of CO2 laser irradiation on in-ceram alumina roughness: a pilot study

Abstract Objectives. The aim of the study was to determine the effect of CO2 laser on surface roughness of In-Ceram-Alumina-ceramic. Materials and methods. Four aluminum-oxide ceramic disc specimens were prepared of In-Ceram Alumina. Discs received CO2 laser irradiation with different engraving speeds (100, 400, 600 and 800 mm/min) as a surface treatment. The roughness of the surfaces was measured on digital elevation models reconstructed from stereoscopic images acquired by scanning-electron-microscope. Surface roughness data were analyzed with One-Way-Analysis-of-Variance at a significance level of p < 0.05. Results. There was no significant difference between the roughness values (p = 0.82). Due to higher laser durations, partial melting signs were observed on the surfaces. Tearing, smearing and swelling occurred on melted surfaces. Swelling accompanying melting increased the surface roughness, while laser power was fixed and different laser engraving speeds were applied. Conclusion. Although different laser irradiation speeds did not affect the roughness of ceramic surfaces, swelling was observed which led to changes on surfaces.

Effect of different core build‐up materials on strength of post restored teeth

Abstract The aim of the present paper is to determine shear bond strengths (SBSs) of core build‐up materials placed on post retained endodontically treated teeth. Following endodontic treatment, prefabricated posts were placed on 84 extracted maxillary first molar teeth. Core materials including high copper admixed silver amalgam (Duralloy; control group), dual cured adhesive core materials (Bis‐Core, LuxaCore Dual and Rebilda DC), organically modified ceramic (Admira), light cured resin composite (Filtek Z250) and silver reinforced glass ionomer cement (Argion Molar) were placed. Shear bond strength was tested in a universal testing machine (crosshead speed = 1 mm min−1). The Mann–Whitney U test followed by Bonferroni post hoc correction was used for statistical analysis (significance level = 0·05). While Filtek Z250 exhibited the highest SBS values (p<0·05), Argion Molar showed the lowest values (p<0·05). Bis‐Core, LuxaCore Dual, Rebilda DC and Admira groups had similar bond strengths (p>0·05). Duralloy revealed higher SBS values in comparison to Rebilda DC group (p<0·05). According to SBS values, dual or light cured resin composites may be used as alternatives to amalgam.