Dentistry Commons^™

Authentic Leadership In Illness Blogs: What We Can Learn From Jaw Surgery Bloggers, Marilyn Mitchell

Marilyn Mitchell

This paper argues that authentic leadership theory provides a useful model for explaining the communication of orthognathic or jaw surgery bloggers. Previous studies concluded that illness blogs can empower patients, but no research considered any leadership theory as a model for blogging. For this study, 24 publicly available blogs were analyzed to find expressions that demonstrated each of the four components of authentic leadership, which are self-awareness, relational transparency, communication based upon an internalized moral perspective, and balanced processing of information. The research also analyzed blog comments to find expressions that demonstrated followers’ development of the positive psychological capacities of …

Orofacial Pain Overview: Getting Rid Of The Riddles, Andrew L. Young

Andrew L. Young

While most pains that find their way to the dental office are dental in origin, some have less familiar roots: muscular, joint, neurological, headache, sinus or psychological. All of these roots can at times masquerade as a toothache. The purpose of this article is to alert the dentist to the select features of each root that distinguish it from the rest, resulting in efficient and appropriate treatment.

Antimicrobial Peptide Coating Of Dental Implants: Biocompatibility Assessment Of Recombinant Human Beta Defensin-2 For Human Cells, Patrick Warnke, Eske Voss, Paul Russo, Sebastien Stephens, Michael Kleine, Hendrik Terheyden, Qin Liu

Qin Liu

Purpose: Artificial materials such as dental implants are at risk of bacterial contamination in the oral cavity. Human beta defensins (HBDs), small cationic antimicrobial peptides that exert a broad-spectrum antibacterial function at epithelial surfaces and within some mesenchymal tissues, could probably help to reduce such contamination. HBDs also have protective immunomodulatory effects and have been reported to promote bone remodeling. The aim of this study, therefore, was to investigate the influence of recombinant HBD-2 on the proliferation and survival of cells in culture.

Materials and Methods: Human mesenchymal stem cells (hMSCs), human osteoblasts, human keratinocytes (control), and the HeLa cancer …

Comparison Of In Vitro Biocompatibility Of Nanobone(®) And Biooss(®) For Human Osteoblasts, Qin Liu, Timothy Douglas, Christiane Zamponi, Stephan Becker, Eugene Sherry, Sureshan Sivananthan, Frauke Warnke, Jörg Wiltfang, Patrick Warnke

Qin Liu

Introduction:Scaffolds for bone tissue engineering seeded with the patient's own cells might be used as a preferable method to repair bone defects in the future. With the emerging new technologies of nanostructure design, new synthetic biomaterials are appearing on the market. Such scaffolds must be tested in vitro for their biocompatibility before clinical application. However, the choice between a natural or a synthetic biomaterial might be challenging for the doctor and the patient. In this study, we compared the biocompatibility of a synthetic bone substitute, NanoBone®, to the widely used natural bovine bone replacement material BioOss®.Material and methods: The in …

Proliferation Assessment Of Primary Human Mesenchymal Stem Cells On Collagen Membranes For Guided Bone Regeneration, Qin Liu, A. Humpe, D. Kletsas, F. Warnke, S. Becker, T. Douglas, S. Sivananthan, P. Warnke

Qin Liu

Purpose: Human mesenchymal stem cells (hMSCs) hold the potential for bone regeneration because of their self-renewing and multipotent character. The goal of this study was to evaluate the influence of collagen membranes on the proliferation of hMSCs derived from bone marrow. A special focus was set on short-term eluates derived from collagen membranes, as volatile toxic materials washed out from these membranes may influence cell behavior during the short time course of oral surgery.

Materials and Methods: The proliferation of hMSCs seeded directly on a collagen membrane (BioGide) was evaluated quantitatively using the cell proliferation reagent WST-1 (4-3-[4-iodophenyl]-2-[4-nitrophenyl]-2H-[5-tetrazolio]-1, …

A Retrospective Review Of Clinical International Normalized Ratio Results And Their Implications, Thomas Radmer, Moawia Kassab, James Glore

Thomas W Radmer

Warfrin is a key element in therapy for atrial fibrillation, deep venous thrombosis (DVT), stroke (cerebrovascular accident and cardiac valve replacement . The authors searced 16,017 active clinical charts for active patients of record for the years 2009-2010. The authors found that 1.96 percent of total Marquette University Dental Clinic patients had a history of warfrin use. INR values for a significant number of dental patients are not within the therapeutic range for their medical conditions. The patients physcian was contacted for warfrin dose regulation prior to invasive dental procedures.

Safe Zone For Bone Harvesting From The Interforaminal Region Of The Mandible, O. Al-Ani, P. Nambiar, K. O. Ha, W.C. Ngeow

Wei Cheong Ngeow

Aims: The mandibular incisive nerve can be subjected to iatrogenic injury during bone graft harvesting. Using cone beam computed tomography (CBCT), this study aims to determine a safe zone for bone graft harvesting that avoids injuring this nerve. Methods: Sixty CBCT examinations of patients were included in this study. The examinations were taken using the i-CAT CBCT imaging system, applying a standardized exposure protocol. Image reconstruction from the raw data was performed using the SimPlant dental implant software. The distances of mandibular incisive canal (MIC) to the inferior border and the labial and lingual cortices of the mandible were measured …

Histomorphometric Changes In Repaired Mouse Sciatic Nerves Are Unaffected By The Application Of A Scar-Reducing Agent, W.C. Ngeow, S. Atkins, C. R. Morgan, A. D. Metcalfe, F. M. Boissonade, A. R. Loescher, P. P. Robinson

Wei Cheong Ngeow

Microsurgical repair of transected peripheral nerves is compromised by the formation of scar tissue and the development of a neuroma, thereby limiting the success of regeneration. The aim of this study was to quantify histomorphometrically the structural changes in neural tissue that result from repair, and determine the effect of mannose-6-phosphate (M6P), a scar-reducing agent previously shown to enhance regeneration. In anaesthetised C57-black-6 mice, the left sciatic nerve was sectioned and repaired using four epineurial sutures. Either 100 mu L of 600 mM M6P (five animals) or 100 mu L of phosphate-buffered saline (placebo controls, five animals) was injected into …

Performance Of Melamine Modified Urea-Formaldehyde Microcapsules In A Dental Host Material, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

Urea-formaldehyde (UF) microcapsules filled with dicyclopentadiene (DCPD) show potential for making self-healing dental restorative materials. To enhance the physical properties of the capsules, the urea was partially replaced with 0-5% melamine. The microcapsules were analyzed by different microscopic techniques. DSC was used to examine the capsule shell, and the core content was confirmed by (1)H NMR spectroscopy. Capsules in the range of 50-300 mu m were then embedded in a dental composite matrix consisting of bisphenol-A-glycidyl dimethacrylate (Bis-GMA) and triethylene-glycol dimethacrylate (TEGDMA). Flexural strength, microhardness, and nanoindentation hardness measurements were performed on the light-cured specimens. Optical microscopy (OM) examination showed …

Human Platelet Lysate Permits Scale-Up Of Dental Pulp Stromal Cells For Clinical Applications, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

Background aims. Dental pulp stromal cells (DPSC) are considered to be a promising source of stem cells in the field of regenerative therapy. However, the usage of DPSC in transplantation requires large-scale expansion to cater for the need for clinical quantity without compromising current good manufacturing practice (cGMP). Existing protocols for cell culturing make use of fetal bovine serum (FBS) as a nutritional supplement. Unfortunately, FBS is an undesirable additive to cells because it carries the risk of transmitting viral and prion diseases. Therefore, the present study was undertaken to examine the efficacy of human platelet lysate (HPL) as a …

Development Of Craniofacial Implants Produced By Metal Injection Molding Of Titanium Alloy Using Novel Binder System Based On Palm Oil, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

Metal Injection Molding (MIM) is a cost-effective technique for producing small, complex, precision parts in high volumes. MIM consists of four main processing steps: mixing, injection molding, debinding and sintering. In the mixing step, the powder titanium alloy (Ti6Al4V) medical grade is mixed with a binder system based on palm stearin to form a homogeneous feedstock. The rheological studies of the feedstock have been determined properly in order to success during injection into injection molding machine. After molding, the binder holds the particles in place. The binder systems then have to be removed completely through debinding step. Any contamination of …

Porosity Reduction Model In Titanium - Hydroxyapatite Fgm Composites Using Shrinkage Measurement, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

A multilayered titanium (Ti)‐hydroxyapatite (HA) functionally graded material was produced via pressureless sintering at 1100°C. The initial and final porosities were determined via shrinkage measurements. The final porosity verification was carried out by the Archimedes method. The experimental porosity measurements were compared with two proposed models. The macroscopic and microstructure features and the measured porosities confirmed that the volume fraction porosity was associated with both matrix and reinforcing particles in all cases. The percolation threshold was observed at x = 0·75 in the xTi+(1−x)HA mixture.

The Effect Of Mannose-6-Phosphate On Recovery After Sciatic Nerve Repair, W.C. Ngeow, S. Atkins, C. R. Morgan, A. D. Metcalfe, F. M. Boissonade, A. R. Loescher, P. P. Robinson

Wei Cheong Ngeow

We have determined the effect of applying Mannose-6-Phosphate (M6P), a scar reducing agent, to a site of sciatic nerve repair. In anaesthetised C57-Black-6 mice, the left sciatic nerve was sectioned and repaired using 4 epineurial sutures. Either 100 mu l of 600 mM Mannose-6-Phosphate (29 animals), or 100 mu l of phosphate buffered saline as a placebo control (29 animals), was injected into and around the nerve repair site. A further group acted as sham-operated controls. After 6 or 12 weeks of recovery the extent of regeneration was assessed electrophysiologically and the percentage area of collagen staining at the repair …

Differentiation Of Dental Pulp Stem Cells Into Islet-Like Aggregates, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

The post-natal dental pulp tissue contains a population of multipotent mesenchymal progenitor cells known as dental pulp stromal/stem cells (DPSCs), with high proliferative potential for self-renewal. In this investigation, we explored the potential of DPSCs to differentiate into pancreatic cell lineage resembling islet-like cell aggregates (ICAs). We isolated, propagated, and characterized DPSCs and demonstrated that these could be differentiated into adipogenic, chondrogenic, and osteogenic lineage upon exposure to an appropriate cocktail of differentiating agents. Using a three-step protocol reported previously by our group, we succeeded in obtaining ICAs from DPSCs. The identity of ICAs was confirmed as islets by dithiozone-positive …

A Comparison Between The Effects Of Three Potential Scar-Reducing Agents Applied At A Site Of Sciatic Nerve Repair, W.C. Ngeow, S. Atkins, C. R. Morgan, A. D. Metcalfe, F. M. Boissonade, A. R. Loescher, P. P. Robinson

Wei Cheong Ngeow

We have investigated the effect of three potential scar-reducing agents applied at a sciatic nerve repair site in C57-black-6 mice. Under anaesthesia the nerve was transected, repaired using four epineurial sutures, and 100 mu l of either triamcinolone acetonide (1 mg/100 mu l), an interleukin-10 peptide fragment: (125 ng/100 mu l or 500 ng/100 mu l) or mannose-6-phosphate (M6P, 200 mM or 600 mM) was injected into and around the nerve. After 6 weeks the extent of regeneration was assessed electrophysiologically by determining the ratio of the compound action potential (CAP) modulus evoked by electrical stimulation of the nerve 2 …

Differentiation Of Dental Pulp Stem Cells Into Islet-Like Aggregates, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

The post-natal dental pulp tissue contains a population of multipotent mesenchymal progenitor cells known as dental pulp stromal/stem cells (DPSCs), with high proliferative potential for self-renewal. In this investigation, we explored the potential of DPSCs to differentiate into pancreatic cell lineage resembling islet-like cell aggregates (ICAs). We isolated, propagated, and characterized DPSCs and demonstrated that these could be differentiated into adipogenic, chondrogenic, and osteogenic lineage upon exposure to an appropriate cocktail of differentiating agents. Using a three-step protocol reported previously by our group, we succeeded in obtaining ICAs from DPSCs. The identity of ICAs was confirmed as islets by dithiozone-positive …

Structural And Compositional Characterization Of Silverfil Amalgam, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

SilverFil (Silverfildental Products, Malaysia) is another commercially available dental amalgam; however it is based on silver and mercury only. It is claimed that upon amalgamation, there is no excess mercury in SilverFil. Objectives: The objectives of this study were to determine the structural state and chemical composition of the starting materials and presence of mercury in the resulting amalgam. Methods: All the starting materials of SilverFil and the SilverFil amalgam specimens were characterize using Field Emission Scanning Electron Microscopy (FESEM-EDX), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). Results: The FESEM images of the amalgam shows silver-mercury (Ag-Hg) clusters. The …

Decompression Of Inferior Alveolar Nerve: Case Report Comment, W.C. Ngeow

Wei Cheong Ngeow

Paresthesia as a result of mechanical trauma is one of the most frequent sensory disturbances of the inferior alveolar nerve. This case report describes surgical treatment for paresthesia caused by a compressive phenomenon within the mandibular canal. The cause of the compression, a broken instrument left in the patient's mouth during previous endodontic therapy, was identified during routine radiography and computed tomography. Once the foreign object was removed by surgery, the paresthesia resolved quickly. This case highlights the potential for an iatrogenic mechanical cause of paresthesia.

Optimization Of Microencapsulation Process For Self-Healing Polymeric Material, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

A series of poly(urea-formaldehyde) (PUF) microcapsules filled with dicyclopentadiene (DCPD) was successfully prepared by in situ polymerization. The effect of diverse process parameters and ingredients on the morphology of the microcapsules was observed by SEM, optical microscopy (OM) and digital microscopy. Different techniques for the characterization of the chemical structure and the core content were considered such as FT-IR and (1)H-NMR as well as the characterization of thermal properties by DSC. High yields of free flowing powder of spherical microcapsules were produced. The synthesized microcapsules can be incorporated into another polymeric host material. In the event the host material cracks …

3d-Fe Analysis Of Functionally Graded Structured Dental Posts, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

This study aimed to compare the biomechanical behaviour of functionally graded structured posts (FGSPs) and homogenous-type posts in simulated models of a maxillary central incisor. Two models of FGSPs consisting of a multilayer xTi-yHA composite design, where zirconia and alumina was added as the first layer for models A and B respectively were compared to homogenous zirconia post (model C) and a titanium post (model D). The amount of Ti and HA in the FGSP models was varied in gradations. 3D-FEA was performed on all models and stress distributions were investigated along the dental post. In addition, interface stresses between …

Thermo-Mechanical Stress In Multilayered Dental Post Due To Temperature Gradient, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

Objective: To analyse thermo-mechanical stress in endodontically treated teeth restored with Multilayered Structured Dental Posts (MSDPs) under cold and hot conditions using Finite Element Analysis (FEM). Methods: Three MSDPs of multilayer design of xTi-yHA composition added to a zirconia layer (model A), an alumina layer (model B) and a titanium layer (model C) were compared with zirconia (model D) and titanium (model E) posts. The fractions of Ti and HA was varied gradually. Changes in temperature of an endodontically restored tooth model were calculated as a result of hot and cold response. The resulting thermo-mechanical stresses were analysed and compared …

Inherent Differential Propensity Of Dental Pulp Stem Cells Derived From Human Deciduous And Permanent Teeth, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

Introduction: Lately, several new stem cell sources and their effective isolation have been reported that claim to have potential for therapeutic applications. However, it is not yet clear which type of stem cell sources are most potent and best for targeted therapy. Lack of understanding of nature of these cells and their lineage-specific propensity might hinder their full potential. Therefore, understanding the gene expression profile that indicates their lineage-specific proclivity is fundamental to the development of successful cell-based therapies. Methods: We compared proliferation rate, gene expression profile, and lineage-specific propensity of stem cells derived from human deciduous (SCD) and permanent …

Is There A "Safety Zone" In The Mandibular Premolar Region Where Damage To The Mental Nerve Can Be Avoided If Periapical Extrusion Occurs?, W.C. Ngeow

Wei Cheong Ngeow

The mandibular premolars are located close to the mental foramina (Fig. 1). As such, various events affecting these teeth, such as odontogenic infection1 and orthodontic, endodontic, periodontal or surgical misadventure, may result in neurosensory disturbance of the mental nerves.2-4 In one retrospective study, the incidence of mental paresthesia resulting from periapical infection or pathology was 0.96%. In another 0.24% of cases in the same study, mental paresthesia was a complication of root canal treatment (caused by severe overfill in one case and iatrogenic perforation of mechanical instrumentation through the root and into the mental nerve in the second case).1 The …

Scar Less: A Review Of Methods Of Scar Reduction At Sites Of Peripheral Nerve Repair, W.C. Ngeow

Wei Cheong Ngeow

Scar formation is important for normal wound healing but proliferation of scar tissue from the epineurium in response to a nerve injury will result in impediment to the regenerating axons that need to traverse the repaired site. This article reviews the events that occur after peripheral nerve transection and the challenges that need to be addressed to reduce scarring in order to improve nerve regeneration. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: 357-366)

Injection Of Botulinum Toxin Type A (Botox) Into Trigger Zone Of Trigeminal Neuralgia As A Means To Control Pain, W.C. Ngeow, R. Nair

Wei Cheong Ngeow

This article illustrates a case of persistent trigeminal neuralgia in a medically compromised 65-year-old female who did not respond to pharmacotherapy. She had undergone several peripheral neurectomies as well as a failed right posterior fossa exploration that resulted in a cerebrospinal fluid leak. Persistent pain over the right external nasal area and right mental region was relieved for several hours after daily injections of bupivacaine. A trial of a single dose of 100 units of botulinum toxin type A (BOTOX) diluted in 2.5 mL saline was injected into the external nasal trigger zone (60 units) and to the mental nerve …

Cytotoxicity Of Polyurethane Dimethacrylate Derived From Palm Oil Polyol., Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

Objective: The aim of this study was to investigate the cytotoxicity effect of polyurethane dimethacrylate monomer derived from palm oil polyol (PUDMA) and 2 experimental composite resins based on these monomer PUDMA- based composites) compared to an experimental Bis-GMA/TEGDMA-based composite and EsthetX flowable composite (Dentsply, Caulk, USA). Methods: The experimental composite resins were prepared by mixing 0.25% and 0.75% by weight camphorquinone and ethyl (4-dimethyl amino) benzoate with 60% filler for each of the following monomer systems; I) PUDMA monomer (PUDMA-based composite resin), II) Bis-GMA/TEGDMA at ratio of 75:25 by weight, III) PUDMA/BisGMA-TEGDMA at ratio of 50:50 by weight. Eight …

Surface Reproduction Of Elastomeric Materials: Viscosity And Groove Shape Effects, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

Objective: To evaluate the effect of viscosity and type of grooves on surface detail reproduction of elastomeric impression materials. Methods: Express putty/light-, Impregum medium- and heavy/light-bodied and Aquasil medium- and putty/light-bodied elastomeric impression materials were chosen for this study. Five impressions were made using a cylindrical aluminum reference block with U- and V- shaped grooves and to produce 35 master dies. Each master die was immersed in distilled water at 370 C for 5 minutes prior to the impression making on moist surfaces. Surface topography of the dies and impressions were captured using Alicona Imaging System. The mean difference in …

A Finite Element Study Of The Multilayered Structured Dental Post, Noor Hayaty Abu Kasim Abu Kasim N.H.

Noor Hayaty Abu Kasim Abu Kasim N.H.

Ideally, dental post should have stiffness that is similar to the crown at the coronal part and stiffness similar to the dentine at the apical part. This will reduce stress concentration at either coronal or the apical parts of the dentine and minimize the chance of interfacial loosening and enhance the reliability of post. Objective: To investigate the biomechanical behaviour of Multilayered Structured Dental Posts (MSDPs) using finite element analysis (FEA). Methods: Two models of MSDPs consist of multilayer design of xTi-yHA composition added to a zirconia layer (model A) and the same compositions added to alumina layer (model B) …

Numbness Of The Ear Following Inferior Alveolar Nerve Block: The Forgotten Complication, W.C. Ngeow, W. L. Chai

Wei Cheong Ngeow

This article presents a distant complication in the auricle following the administration of a standard inferior alveolar nerve block. The patient experienced profound numbness of the auricle on the ipsilateral side of the injection that lasted for about an hour following unintended injection to the auriculotemporal nerve.

Craniofacial Anthropometric Norms Of Malaysian Indians, W.C. Ngeow, S. T. Aljunid

Wei Cheong Ngeow

Objective: This study was done to establish the craniofacial anthropometric norms of the young adult (18-25 years) Malaysian Indian. Materials and Methods: The study group consisted of convenient samples of 100 healthy volunteers, with equal number of female and male subjects who had no history of mixed racial-parentage. Twenty-two linear measurements were taken twice from 28 landmarks over six craniofacial regions. The methodology and evaluation of indices of the craniofacial region was adapted from Hajnis et al. Results: The minimum measurements are always contributed by the female Indian except for the nose height (n-sn), (left) eye fissure length (ex-en), upper …