Orhan Hamamci

Bio: Orhan Hamamci is an academic researcher from Dicle University. The author has contributed to research in topics: Malocclusion & Overbite. The author has an hindex of 9, co-authored 18 publications receiving 409 citations.

Etching Enamel for Orthodontics with an Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet Laser System

Abstract: Objective: To test the shear bond strength, surface characteristics, and fracture mode of brackets that are bonded to enamel etched with an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser operated at different power outputs: 0.5 W, 1 W, and 2 W. Materials and Methods: Human premolars that had been extracted for orthodontic purposes were used. Enamel was etched with an Er,Cr:YSGG laser system operated at one of three power outputs or with orthophosphoric acid. Results: The shear bond strength associated with the 0.5-W laser irradiation was significantly less than the strengths obtained with the other irradiations. Both the 1-W and 2-W laser irradiations were capable of etching enamel in the same manner. This finding was confirmed by scanning electron microscopy examination. The evaluation of adhesive-remnant-index scores demonstrated no statistically significant difference in bond failure site among the groups, except for the 0.5-W laser–etched group. Generally, more adhesive w...

Intermaxillary Bolton Tooth Size Discrepancies Among Different Malocclusion Groups

Abstract: The orthodontic "finishing" phase is recognized for the many details necessary to accomplish an excellent result. A high percentage of finishing-phase difficulties arise because of tooth size imbalances that could have been discovered and considered during the initial diagnosis and treatment planning. The aim of our study was to determine whether there is a prevalent tendency for intermaxillary tooth size discrepancies among different malocclusion groups. This study involved 60 subjects who served as the normal occlusion group and 300 patients divided into five malocclusion groups (ie, Class I, Class II, Class II division 1, Class II division 2, and Class III). Tooth size measurements were performed on the models of the normal occlusion group and the pretreatment models of the patients. The tooth size ratios and the one-way analysis of variance test showed no sexual dimorphism for these ratios in each of five groups, so the sexes were combined for each group. Then, these ratios were compared among different malocclusion groups. The results showed no significant difference between subcategories of malocclusion, so these groups were combined as Class I, Class II, and Class III. No significant difference was found for all the ratios between the groups.

Interleukine-1β and Tumor Necrosis Factor–α Levels in the Human Gingival Sulcus during Orthodontic Treatment

Abstract: Objective: To test whether interleukine 1β (IL-1β) and tumor necrosis factor–α (TNF-α) levels differ from each other in different treatment levels. Materials and Methods: Eighteen patients, nine female and nine male (aged 16–19 years; mean 17.4 ± 1.8 years), participated in this study. Each subject underwent a session on professional oral hygiene and received oral hygiene instructions. Two months later, a fixed orthodontic appliance was placed. The patients were seen at baseline, at days 7 and 21 and at the 3rd and 6th month as the leveling of the teeth occurred. Records of the baseline scores for the distalization forces were taken at the 6th month. Days 7 and 21 after 6 months of treatment were also recorded. Results: There were increases in the volume of gingival crevicular fluid (GCF) and in the concentrations of IL-1β and TNF-α. Conclusions: Leveling and distalization of the teeth evoke increases in both the IL-1 and TNF-α levels that can be detected in GCF.

One-year follow-up of the effect of fixed orthodontic treatment on colonization by oral Candida.

Abstract: The aim of this study was to assess quantitative and qualitative alterations in the carrier rate of Candida spp. in south-eastern Turkey among adolescents, and to investigate the effect of fixed orthodontic appliances on the Candida count in a 1-year follow-up study. In the first phase of the study, the oral Candida carriage rate of 72 patients was evaluated. Samples were collected from the dorsal surface of the tongue, the mid-palate and saliva. In the second phase of the study, 42 patients who were determined to be carriers of oral Candida were treated with fixed orthodontic appliances, and from these patients a second set of samples were collected from the saliva and the orthodontic brace surfaces of eight teeth adjacent to the enamel surfaces. The saliva samples were collected before and during orthodontic treatment at 1st, 6th and 12th month, and samples from the braces were collected during the 1st, 6th and 12th month of treatment. Forty-two of the 72 patients (58.5%) were oral Candida carriers. The distribution of Candida spp. in these patients was as follows: (i) Candida albicans was identified in 31 patients (73.8%), (ii) C. tropicalis, C. krusei and C. kefyr were found in three patients each (7.14%) and (iii) C. parapsilosis occurred in two patients (4.76%). During orthodontic treatment, the micro-organism count increased both in the saliva and on tooth surfaces. The results indicate that the prevalence of oral Candida spp. is high in young adults in south-eastern Turkey and that the Candida counts increase when braces are involved.

Mechanisms of Tooth Eruption and Orthodontic Tooth Movement

Abstract: Teeth move through alveolar bone, whether through the normal process of tooth eruption or by strains generated by orthodontic appliances. Both eruption and orthodontics accomplish this feat through similar fundamental biological processes, osteoclastogenesis and osteogenesis, but there are differences that make their mechanisms unique. A better appreciation of the molecular and cellular events that regulate osteoclastogenesis and osteogenesis in eruption and orthodontics is not only central to our understanding of how these processes occur, but also is needed for ultimate development of the means to control them. Possible future studies in these areas are also discussed, with particular emphasis on translation of fundamental knowledge to improve dental treatments.

Cytokine Expression and Accelerated Tooth Movement

Abstract: It has been shown that inhibiting the expression of certain cytokines decreases the rate of tooth movement. Here, we hypothesized that stimulating the expression of inflammatory cytokines, through small perforations of cortical bone, increases the rate of bone remodeling and tooth movement. Forty-eight rats were divided into 4 groups: 50-cN force applied to the maxillary first molar (O), force application plus soft tissue flap (OF), force application plus flap plus 3 small perforations of the cortical plate (OFP), and a control group (C). From the 92 cytokines studied, the expression of 37 cytokines increased significantly in all experimental groups, with 21 cytokines showing the highest levels in the OFP group. After 28 days, micro-computed tomography, light and fluorescent microscopy, and immunohistochemistry demonstrated higher numbers of osteoclasts and bone remodeling activity in the OFP group, accompanied by generalized osteoporosity and increased rate of tooth movement.

Candida Species Biofilms’ Antifungal Resistance

Abstract: Candida infections (candidiasis) are the most prevalent opportunistic fungal infection on humans and, as such, a major public health problem. In recent decades, candidiasis has been associated to Candida species other than Candida albicans. Moreover, biofilms have been considered the most prevalent growth form of Candida cells and a strong causative agent of the intensification of antifungal resistance. As yet, no specific resistance factor has been identified as the sole responsible for the increased recalcitrance to antifungal agents exhibited by biofilms. Instead, biofilm antifungal resistance is a complex multifactorial phenomenon, which still remains to be fully elucidated and understood. The different mechanisms, which may be responsible for the intrinsic resistance of Candida species biofilms, include the high density of cells within the biofilm, the growth and nutrient limitation, the effects of the biofilm matrix, the presence of persister cells, the antifungal resistance gene expression and the increase of sterols on the membrane of biofilm cells. Thus, this review intends to provide information on the recent advances about Candida species biofilm antifungal resistance and its implication on intensification of the candidiasis.

Effect of cytokines on osteoclast formation and bone resorption during mechanical force loading of the periodontal membrane.

Abstract: Mechanical force loading exerts important effects on the skeleton by controlling bone mass and strength. Several in vivo experimental models evaluating the effects of mechanical loading on bone metabolism have been reported. Orthodontic tooth movement is a useful model for understanding the mechanism of bone remodeling induced by mechanical loading. In a mouse model of orthodontic tooth movement, TNF-α was expressed and osteoclasts appeared on the compressed side of the periodontal ligament. In TNF-receptor-deficient mice, there was less tooth movement and osteoclast numbers were lower than in wild-type mice. These results suggest that osteoclast formation and bone resorption caused by loading forces on the periodontal ligament depend on TNF-α. Several cytokines are expressed in the periodontal ligament during orthodontic tooth movement. Studies have found that inflammatory cytokines such as IL-12 and IFN-γ strongly inhibit osteoclast formation and tooth movement. Blocking macrophage colony-stimulating factor by using anti-c-Fms antibody also inhibited osteoclast formation and tooth movement. In this review we describe and discuss the effect of cytokines in the periodontal ligament on osteoclast formation and bone resorption during mechanical force loading.

Cytokines in crevicular fluid and orthodontic tooth movement

Abstract: This review aimed to evaluate studies on cytokines in the gingival crevicular fluid (GCF) during orthodontic treatment, summarizing the regulation patterns of the most commonly studied cytokines and exploring their clinical implications. To achieve this, a number of key databases were searched using MESH terms and free text terms. An additional search was made by reference tracking. The procedures suggested by the QUOROM statement were followed. Data from the included studies were extracted into orthodontic mechanics, GCF sampling/handling methods, and cytokine measurements. From the 85 relevant studies identified, 23 studies could be included. Common drawbacks consisted mainly of inadequacies in the study design (e.g. short duration and small number of study subjects). The most consistent result was a peak of cytokine levels at 24 h. Associations existed between prostaglandin E(2) (PGE(2)) and interleukin-1beta (IL-1beta) and pain, velocity of tooth movement, and treatment mechanics. Interleukin-1beta and PGE(2) showed different patterns of up-regulation, with IL-1beta being more responsive to mechanical stress and PGE(2) more responsive to synergistic regulation of IL-1beta and mechanical force. The results might be taken to support, at the cellular level, the use of light continuous forces for orthodontic treatment.