Mohit Kheur

Nano‑hydroxyapatite and its contemporary applications

Combination of nano‑sized hydroxyapatite (nHA) with restorative materials like glass ionomer cement and composite resins has been reported recently in 2011. The documented effects of these nano‑sized particles on the chemistry of these materials include increased biocompatibility and mechanical strength. nHA has been utilized for various applications like pulp capping agent, root canal sealer, filler for bleaching agents and toothpastes, osseo‑conductive bone graft etc., A nHA has been obtained using natural bovine bone, carbon template technique, hydroxyapatite‑chitosan template technique, wet precipitation technique, plasma spraying technique etc. This paper presents a review of the various aspects of nHA and summarizes the methods of fabrications and potential clinical applications of the same.

Evaluation of experimental coating to improve the zirconia-veneering ceramic bond strength.

PURPOSE To evaluate the shear bond strength (SBS) between zirconia and veneering ceramic following different surface treatments of zirconia. The efficacy of an experimental zirconia coating to improve the bond strength was also evaluated. MATERIALS AND METHODS Zirconia strips were fabricated and were divided into four groups as per their surface treatment: polished (control), airborne-particle abrasion, laser irradiation, and application of the experimental coating. The surface roughness and the residual monoclinic content were evaluated before and after the respective surface treatments. A scanning electron microscope (SEM) analysis of the experimental surfaces was performed. All specimens were subjected to shear force in a universal testing machine. The SBS values were analyzed with one-way ANOVA followed by Bonferroni post hoc for groupwise comparisons. The fractured specimens were examined to observe the failure mode. RESULTS The SBS (29.17 MPa) and roughness values (0.80) of the experimental coating group were the highest among the groups. The residual monoclinic content was minimal (0.32) when compared to the remaining test groups. SEM analysis revealed a homogenous surface well adhered to an undamaged zirconia base. The other test groups showed destruction of the zirconia surface. The analysis of failure following bond strength testing showed entirely cohesive failures in the veneering ceramic in all study groups. CONCLUSION The experimental zirconia surface coating is a simple technique to increase the microroughness of the zirconia surface, and thereby improve the SBS to the veneering ceramic. It results in the least monoclinic content and produces no structural damage to the zirconia substructure.

Osteopontin: a marker for invasive oral squamous cell carcinoma but not for potentially malignant epithelial dysplasias.

This study aimed to evaluate and correlate osteopontin (OPN) expression in oral squamous cell carcinoma (OSCC) and potentially malignant disorders including oral leukoplakia and oral submucous fibrosis (OSMF). Expression of OPN was investigated in 140 samples including OSCC, oral leukoplakia, and OSMF with or without dysplasia and normal oral mucosa. By using immunohistochemistry. Both intercellular and intracellular staining of the keratinocytes was considered to be positive, and intensity grading was assessed. Statistical analysis was done using analysis of variance. OPN positivity was detected in 85% cases of OSCC, 55% cases of oral leukoplakia, 35% cases of OSMF, and 60% cases of normal mucosa. These study highlights OPN as a biomarker for malignancy in the form of invasion but not to study progression from dysplasia to malignant transformation.

Three-Dimensional Evaluation of Alveolar Bone and Soft Tissue Dimensions of Maxillary Central Incisors for Immediate Implant Placement: A Cone-Beam Computed Tomography Assisted Analysis.

Introduction:This study explored the relationship between the thickness of bone and soft tissue along the labial and palatal aspect of maxillary central incisors. The influence of overall socket width, labiopalatal positioning of the incisor on the bone, and soft tissue thickness were also investigated. Materials and Methods:This study used cone-beam computed tomography of 150 patients to determine labial, palatal soft and hard tissue thickness, labiopalatal (B-P) socket width and corelated the same to the labiopalatal positioning of maxillary central incisors. Results:Mean (SD) thicknesses of the labial soft tissue at cervical (C), midroot (M), and apical (A) locations and the corresponding bone thicknesses were 1.07 (0.28), 0.987 (0.27), 1.240 (0.41), and 0.928 (0.39), 0.894 (0.52), 1.57 (0.88), respectively. Similarly, palatal soft tissue and bone thicknesses at locations C, M, A were 1.807 (0.66), 1.557 (0.62), 1.639 (0.66), and 1.679 (0.62), 3.439 (1.28), 6.038 (1.63), respectively. Mean (SD) thicknesses of the B-P socket width at location C was 8.047 (0.963). Conclusions:There is a positive correlation between the labial and palatal bone and corresponding soft tissue thickness, between thickness of the labial bone and the labiopalatal thickness of the alveolar socket. No correlation was observed between the thickness of the labial cortical bone and the labiopalatal positioning of the tooth.

Nanoscale silver depositions inhibit microbial colonization and improve biocompatibility of titanium abutments

Although titanium dental implants are biocompatible, exhibit excellent corrosion resistance and high mechanical resistance, the material fails in providing resistance to infection because it exhibits poor antimicrobial activity. To address these issues, we deposited silver onto titanium abutments (Grade 5 titanium discs) using direct current (DC) sputtering and assessed the antimicrobial activity and biocompatibility of the modified implant material. Atomic absorption spectrometry and X-ray photoelectron spectroscopy were employed to investigate the concentration and elemental composition of the deposited silver. As expected, silver deposited using DC plasma was uniform and good control over the deposition could be achieved by varying the sputtering time. Moderate biocompatible responses (up to 69% viability) were observed in primary human gingival fibroblast cells incubated in the presence of Ti sputtered with Ag for 5min. Silver deposited titanium (Ti-Ag) showed excellent antibacterial effects on Pseudomonas aeruginosa and Streptococcus mutans at a very low concentration (Ag content 1.2 and 2.1μg/mm2). However, higher concentration of silver (6μg/mm2) was required to achieve a reduction in cell viability of Staphylococcus aureus and Candida albicans. The silver sputtered Ti abutments could maintain a long-term antibacterial activity as evidenced by the release of silver up to 22days in simulated body fluid. Our study illustrates that silver deposited titanium is indeed a promising candidate for soft tissue integration on dental abutments and prevents initial microbial adhesion.

Total Mandibular Reconstruction and Rehabilitation: A Case Report

T reatment of mandibular discontinuity defects is a great clinical challenge. Partial or complete mandibulectomy is the surgical treatment of choice for patients diagnosed with malignant oral lesions involving the mandible. The use of microvascular grafts to minimize the impairment of function, speech, and esthetics is the mainstay of modern surgical approach of the reconstructive team. Advances in microvascular surgery have provided the surgeon with methods to repair the partially resected mandible with vital bone grafts. Vascularized bone is used for the secondary reconstructions with large defect, where soft tissue is inadequate, or where the recipient bed has been compromised by radiation, chronic infection, or previous surgery. Often, however, reconstruction of the bony defect alone does not guarantee an adequate foundation for successful conventional prosthetic rehabilitation. Osseointegrated implants placed into the microvascularized grafted bone offer an opportunity for improved function and patient satisfaction and have become the preferred treatment modality. A variety of donor sites have been used for this purpose, including the iliac crest, radius, scapula, and fibula. However, currently the microvascular free fibula flap represents a versatile reconstruction method after mandibularablation. The free fibular microvascular flap was one of the earliest osseous free flaps with successful application in large bony defects. Hidalgo was the first to report the use of a fibula vascularized flap for mandibular reconstruction with 100% osseous survival in a series of 13 patients. Some of the documented advantages of using free fibular microvascular flaps are

Unconventional Causes of Conventional Oral Cancer

Most common cancer diagnosed in Indian men which is also the leading cause of cancer death is the oral cancer. Concept of oral cancer has been widely described as multietiogenic. Though, tobacco, alcohol, areca nut are the common causes of oral cancer, increased incidence of head and neck cancers have been reported in individuals even without any habit. The most common among them are infections and chronic irritations, which lead to inflammatory response alteration leading to increased mutagenesis. Hence, a different approach considering the appropriate facts is necessary. The paper highlights the current researches on etiological role on uncommon facts of viral, bacterial, fungal and chronic irritational causes of oral cancer.

Reduction of excess cement during cementation of implant-retained crowns: A clinical tip

The osseointegrated implants has changed the treatment methods of edentulous patients. This technical note presents a simple chair side technique to minimize the overflow of cement at the time of cementation with the use of a custom-made abutment replica during the placement of an implant retained crown.

Evaluation of the effect of ultraviolet stabilizers on the change in color of pigmented silicone elastomer: An in vitro study

Aim and Objective: To compare and evaluate the effect of ultraviolet (UV) stabilizers (Chimassorb 81 and Uvinul 5050) on the color change of pigmented elastomer. Materials and Methods: Two pigments - Red (P112 Brilliant Red) and Yellow (P106 Yellow) and two UV stabilizers Chimassorb 81 and Uvinul 5050 were studied. A total of six groups of 10 samples each were fabricated using a combination of the above colors and stabilizers: Group A1 - Red control, Group A2 - Red + Chimassorb 81, Group A3 - Red + Uvinul 5050. Group B1 - Yellow control, Group B2 - Yellow + Chimassorb 81, Group B3 - Yellow + Uvinul 5050. All samples were subjected to ageing in an accelerated weathering chamber (Weather-Ometer). Color values L, a, and b were measured at 500 and 1000 h for all samples before and after weathering and change in color (Delta E) was calculated. Results: All groups showed a significant color change. At 500 h, Chimassorb 81 showed a statistically significant lesser change in both colors (red - 3.66 and yellow - 2.8) compared to their control groups (red - 5.19 and yellow - 4.9). At 1000 h, both UV stabilizers showed lesser color change (A2 - 5.49, B2 - 4.28, A3 - 7.47 and B3 - 4.09) as compared to their respective control groups (A1 - 9.57 and B1 - 5.91). Overall, the change in the color with Group A was more than Group B. Conclusion: Addition of UV stabilizers helped the reduction of color change. Chimassorb 81 showed a greater reduction in color change in both colors consistently at 500 and 1000 h.

Prevalence of Viral Coinfections with EBV and CMV and Its Correlation withCD4 Count In HIV-1 Serpositive Patients

Objectives: The objective of this study is to estimate the level of antibodies to EBV and Human Cytomegalovirus (HCMV) in peripheral blood in seropositive HIV-1 patients and its correlation with CD4 cell count and clinical and demographical details. Materials and Methods: 60 patients who are HIV-1 seropositive were included in the study, with 30 seronegative patients as control group. After proper written consent, thorough oral examination was done and CD4 cell count of the patient was noted. Serological assessment of antibodies against EBV & CMV was done as an indicator for viral coinfection in these patients. Results: There was a significant increase in the antibody titer against EBV & CMV in the patients with CD4 count less than 200 as compared to HIV-1 seropositive patients with CD4 count more than 200. The oral manifestations were seen more prominently in direct correlation with CD4 count of the patients. Conclusion: There was a higher titre of EBV-1 and CMV antibodies in HIV-1 seropositive patients. A correlation between antibodies to CMV and CD4 count is seen in our population, with 86.4% of patients presenting with oral manifestations.