bluuebunny/crossref_metadata_2025 huggingface dataset:
Bone Response to Free‐Form Fabricated Hydroxyapatite and Zirconia Scaffolds: A Transmission Electron Microscopy Study in the Human Maxilla
Authors: Grandfield Kathryn , Palmquist Anders , Ericson Fredric , Malmström Johan , Emanuelsson Lena , Slotte Christer , Adolfsson Erik , Botton Gianluigi A. , Thomsen Peter , Engqvist Håkan
Published: February 2010

Background: Understanding the interfacial reactions to synthetic bone regenerative scaffolds in vivo is fundamental for improving osseointegration and osteogenesis. Using transmission electron microscopy, it is possible to study the biological response of hydroxyapatite (HA) and zirconia (ZrO2) scaffolds at the nanometer scale.

Purpose: In this study, the bone‐bonding abilities of HA and ZrO2 scaffolds produced by free‐form fabrication were evaluated in the human maxilla at 3 months and 7 months.

Materials and Methods: HA and ZrO2 scaffolds (ø: 3 mm) were implanted in the human maxilla, removed with surrounding bone, embedded in resin, and sectioned. A novel focused ion beam (FIB) sample preparation technique enabled the production of thin lamellae for study by scanning transmission electron microscopy.

Results: Interface regions were investigated using high‐angle annular dark‐field imaging and energy‐dispersive X‐ray spectroscopy analysis. Interfacial apatite layers of 80 nm and 50 nm thickness were noted in the 3‐ and 7‐month HA samples, respectively, and bone growth was discovered in micropores up to 10 µm into the samples.

Conclusions: The absence of an interfacial layer in the ZrO2 samples suggest the formation of a direct contact with bone, while HA, which bonds through an apatite layer, shows indications of resorption with increasing implantation time. This study demonstrates the potential of HA and ZrO2 scaffolds for use as bone regenerative materials.
Deformation of Stereolithographically Produced Surgical Guides: An Observational Case Series Report
Authors: Stumpel Lambert J.
Published: February 2010

Background: Template‐based computer‐guided implant placement holds the promise of more precise and less traumatic placement of dental implants. Errors in the fabrication process of the surgical guide may lead to unfavorable clinical outcomes.

Purpose: This report discusses the potential of unintentional volumetric deformation of stereolithographically (SLA) produced surgical guides (NobelGuide, Nobel Biocare AB, Göteborg, Sweden) compared with the original scan denture.

Materials and Methods: Three‐dimensional radiographic data acquired by medical computerized tomography (CT) or cone beam CT (Newtom 3G, AFP Imaging Corporation, Elmsford, NY, USA) can be utilized in specialized software to develop treatment planning for dental implant placement.

This information can then be transferred to the patient via a surgical guide. Stereolithography is a rapid prototyping process that can be used to create such a guide stent. Three cases are shown describing different levels of deformation of SLA‐produced surgical guides.

Results: Unintentional deformation of SLA‐produced surgical guides is possible. Deformation of surgical guides can create dissimilarity between the virtually planned position and the actual position of the implants.

Conclusion: Incorrect setting of the ISO values for the segmentation of the scan denture has been found to be a factor in the deformation of SLA‐produced surgical guides, although more, at this time known but also less understood, issues appear to be involved. Only one manufacturer's product is discussed; further research is warranted to determine if the discrepancies are process or product based. It might be prudent to closely evaluate the volumetric congruence of SLA‐produced surgical stents before their clinical use to prevent undesired clinical outcomes.
Longitudinal Changes in Tooth/Single‐Implant Relationship and Bone Topography: An 8‐Year Retrospective Analysis
Authors: Chang Moontaek , Wennström Jan L.
Published: February 2010

Purpose: To evaluate longitudinal changes in tooth/implant relationship and bone topography at single implants with a microthreaded, conical marginal portion (Astra Tech ST® implants, Astra Tech AB, Mölndal, Sweden).

Material and Methods: Thirty‐one subjects with single implant–supported restorations in the esthetic zone were included. Radiographs obtained at crown installation and 1, 5, and 8 years of follow‐up were analyzed with regard to changes in (1) bone level at the implant and adjacent teeth and (2) vertical position of adjacent teeth relative to the single implant.

Results: The mean marginal bone loss amounted to 0.1 mm at both implants and adjacent teeth during the 8 years of follow‐up. Regression analysis failed to identify significant explanatory factors for observed variance in bone level change at the adjacent tooth surfaces. Vertical change in position of the teeth relative to the implants was more frequent and significantly greater in incisor compared with premolar tooth region but not associated with gender or age.

Conclusions: The marginal bone level at teeth adjacent to single implants with a microthreaded conical marginal part was not influenced by horizontal and vertical tooth‐implant distances. Continuous eruption of adjacent teeth may result in infraocclusal positioning of a single‐implant restoration.
Catalytically active membrane‐distal phosphatase domain of receptor protein‐tyrosine phosphatase α is required for Src activation
Authors: Vacaru Andrei M. , den Hertog Jeroen
Published: February 2010

Receptor protein‐tyrosine phosphatase α (RPTPα) is a transmembrane protein with tandem cytoplasmic phosphatase domains. Most of the catalytic activity is contained by the membrane‐proximal catalytic domain (D1). We found a spontaneous Arg554 to His mutation in the pTyr recognition loop of the membrane‐distal phosphatase domain (D2) of a human patient. This mutation was not linked to the disease. Here, we report that the R554H mutation abolished RPTPα‐D2 catalytic activity. The R554H mutation impaired Src binding to RPTPα. RPTPα, with a catalytic site cysteine to serine mutation in D2, also displayed diminished binding to Src. Concomitant with decreased Src binding of the R554H and C723S mutants compared with wild‐type RPTPα, enhanced phosphorylation of the inhibitory Src Tyr527 site was observed, as well as reduced Src activation. To confirm that catalytic activity of RPTPα‐D2 was required for these effects, we analyzed a third mutant, RPTPα‐R729K, which had an inactive D2. Again, Src binding was reduced and Tyr527 phosphorylation was enhanced. Our results suggest that a catalytically active D2 is required for RPTPα to bind and dephosphorylate its well‐characterized substrate, Src.

Structured digital abstract

 MINT‐7551862, MINT‐7552454, MINT‐7552515: Src (uniprotkb:P12931) physically interacts (MI:0915) with RPTP alpha (uniprotkb:P18052) by anti bait coimmunoprecipitation (MI:0006)
Pharmacodynamic Effects in the Cardiovascular System: The Modeller’s View
Authors: Fink Martin , Noble Denis
Published: February 2010

Abstract: Cardiovascular disease, and the cardiovascular side effects of drugs, are essentially multifactorial problems involving interactions between many proteins, dependent on highly organized cell, tissue and organ structures. This is one reason why the side effects of drugs are often unanticipated. It is impossible to unravel such problems without using a systems approach, i.e. focussing on processes, not just molecular components. This inevitably involves modelling as the interactions require quantitative analysis. Modelling is a tool of analysis aimed at understanding, first, and predicting, eventually. We illustrate these principles using modelling of the heart. Models of the cardiac myocyte have benefited from several decades of interaction between experimentation and simulation. They are now sufficiently detailed to have been of use in the development of new drug compounds like ranolazine and ivabradine. With the help of cardiac modelling, we have also been able to unravel the mechanisms underlying the beneficial effect of sodium calcium exchange block for long QT syndrome (LQTS) 2 and LQTS3 patients. Detailed models of the interaction between ion channels and blocking agents provide the basis for modelling drug action from basic principles and predict changes in the inhomogeneous tissue of the heart. We demonstrate that mathematical models are beneficial for unravelling the complex interactions of pharmacodynamics in the heart. Embedding these detailed biophysical cellular scale models into anatomically correct models of the ventricle geometry will enable reconstructions of Torsades de Pointes arrhythmias and of fibrillation, providing a mechanism for linking detailed cellular scale experimental data to clinical applications.
Selenium improves the antioxidant ability against aluminium‐induced oxidative stress in ryegrass roots
Authors: Cartes P. , Jara A.A. , Pinilla L. , Rosas A. , Mora M.L.
Published: February 2010

We investigated the role of selenium (Se) against aluminium (Al) stress in ryegrass by evaluating the growth responses and the antioxidant properties of plants cultured hydroponically with Al (0 or 0.2 mM) and selenite (0–10 µM Se). Al addition significantly reduced the yield and length of shoots and roots, and most Al was accumulated in the roots. Al also enhanced lipid peroxidation and activated the peroxidase (POD), ascorbate peroxidase (APX) and superoxide dismutase (SOD) enzymes in the roots. Se application up to 2 µM improved root growth and steadily decreased thiobarbituric acid reactive substances (TBARS) accumulation in plants treated with 0 and 0.2 mM Al. However, above 2 µM, Se induced stress in plants grown with or without Al. Significant changes in antioxidant enzymes activities were also found as a result of the added Se. At low Se addition levels POD was activated, whereas APX activity decreased irrespective of added Al. Furthermore, Se supplied up to 2 µM greatly decreased root SOD activity in Al‐stressed plants. Our study provides evidence that Se alleviated the Al‐induced oxidative stress in ryegrass roots through the enhancement of the spontaneous dismutation of superoxide radicals and the subsequent activation of POD enzyme.
EFFECT OF CHEMICAL, PHYSICAL AND ENZYMATIC TREATMENTS ON LACTOCOCCUS LACTIS' SURFACE AGGLUTININ AND ITS PRECIPITATING ABILITY
Authors: CHENG SHAN , LIU CHENG , LI SHIFENG , SHEN QUN , ZHENG WEI
Published: February 2010

The precipitating proterty of Lactococcus lactis agglutinin has a negative effect on yield of starch and expanded delaminating time during Chinese traditional mung bean starch processing; thus, it is of interest to find a way to destroy the precipitating property of the agglutinin. In the present study, L. lactis isolated from sour liquid was treated with chemical, physical, and enzymatic methods, respectively. It was found that 12.0–13.7 mol/L of ethanol or 12.3 mol/L of hydrogen peroxide or 0.1 mol/L of HCl, or 0.1 of mol/L NaOH or 0.3 mol/L trichloroacetic acid could destroy the ability of the agglutinin from L. lactis to precipitate starch and expand delaminating time significantly. Periodic acid sodium which destroys the structure of glycosyl also made L. lactis lose its agglutinin activity and precipitating ability. Similarly, pepsin and trypsin had the same function as periodic acid sodium did. The present study might provide a good way to increase the starch yield and delaminating time during the mung bean processing.

PRACTICAL APPLICATIONS

Sour liquid processing has been used for hundreds of years to produce mung bean starch in China because this kind of starch had better quality than that from other processing methods. However, this processing consumed a lot of water while producing a large amount of waste water, resulting in environmental pollution.

Many scientists considered that Lactococcus lactis in sour liquid is the main factor to precipitate starch. The agglutinin on the surface of L. lactis is directly involved in starch deposition. Therefore, our research focuses on improvement of starch yield by using L. lactis‐immobilized columns through which starch slurry passes. This technology will cut down waste water and meet the national requirements, so that we do not doubt the prospect of the technology.

To develop this technology, we should learn what kinds of factors will affect the precipitating ability of agglutinin of L. lactis. This manuscript reports a study on how chemical, physical and enzymatic substance can affect the precipitating ability of agglutinin.
INFLUENCE OF FEED PARAMETERS ON SPRAY DRYING ENERGY CONSUMPTION
Authors: KAJIYAMA TATUMI , PARK KIL JIN
Published: February 2010

The objective of the present research was to simulate and evaluate the performance of spray dryers using MATLAB software. The assessments regarding energy consumption and thermal efficiency were performed. Simulations were conducted to identify the effect of the following parameters' influence on energy consumption: (1) the initial liquid feed moisture content, which ranged from 0.5 kg to 0.9 kg water/kg product, (2) the final moisture content, which ranged from 0.05 kg to 0.3 kg water/kg solid, and (3) the feed flow, ranging from 1 to 10 kg/s. It was found that energy consumption increased with increasing moisture content and feed flow rate and with decreasing final moisture content. The results indicated that the thermal efficiency of the process does not change when process parameters are varied.

PRACTICAL APPLICATIONS

Drying is a process in which food water activity is reduced by water removal to minimize deterioration caused by enzymatic and microbiological reactions and to prevent physical and chemical modification of products. Dried products are used mainly as convenience foods and have long storage life at normal temperatures. Spray drying is a commonly used method of drying a liquid feed through a hot gas in the production of powders. This technique is widely used in food and pharmaceutical manufacturing and presents low operating cost and short contact time. Nowadays, the development of new products has used encapsulating agent, with good emulsifying capacity and low viscosity in aqueous solution, in microencapsulation by spray drying. This wide application of spray drying in research of new product increases the need of engineers to understand energy calculation with mass and heat balance concerning spray‐drying process.
STUDIES ON ENERGY REQUIREMENTS IN MANUFACTURE OF KUNDA – A HEAT DESICCATED INDIAN MILK PRODUCT
Authors: MAHALINGAIAH L. , VENKATESHAIAH B.V. , KULKARNI S. , RAO K. JAYARAJ
Published: February 2010

Kunda is an Indian traditional heat desiccated dairy product popular in Karnataka province of India. Manufacture of Kunda is a time consuming and energy intensive process involving continuous desiccation of milk along with sugar and the process involves consumption of large quantities of steam for evaporation of water. Since energy conservation in dairies is a priority area, a technology was developed to manufacture Kunda with less energy requirement utilizing caramelized sugar. Caramelized sugar was used during the process at various levels and it was observed that browning developed faster with increasing level of caramelized sugar. Use of 40% level of caramelized sugar reduced the total process time and also produced good quality Kunda. The total net energy consumption per kg Kunda was 8262.61 kJ and this energy consumption was brought down by 26.91% utilizing caramelized sugar at 40% level of sugar.

PRACTICAL APPLICATIONS

Several varieties of heat desiccated dairy products are being consumed by the people in India and other South Asian countries. Some of these products are highly region specific. The popularity of these products spans a vast geographical area. Kunda is one such product very popularly consumed in central regions of India. Its manufacture involves taking milk in a steam kettle, boiling for long periods of time along with sugar desiccating the contents to a brown colored semisolid mass, called Kunda. In a dairy plant, this involves consumption of large quantities of steam, which naturally adds to the cost of the product. In the present research work, the steam requirement for Kunda manufacture has been estimated and efforts were made to cut down the steam energy requirement by 26–27%, which translated to significant savings in energy. Thus, consumers not only will have to pay less for the product, but also could enjoy good quality product prepared by the developed technology. This technology has been successfully transferred to one of the dairy plants in the region.
PRODUCTION OF XANTHAN GUM FROM XANTHOMONAS CAMPESTRIS NRRL B‐1459 BY FERMENTATION OF DATE JUICE PALM BY‐PRODUCTS (PHOENIX DACTYLIFERA L.)
Authors: SALAH RIADH BEN , CHAARI KACEM , BESBES SOUHAIL , BLECKER CHRISTOPHE , ATTIA HAMMADI
Published: February 2010

In this work, we studied the possibility to use date juice for xanthan gum production by Xanthomonas campestris NRRL B‐1459. The results showed that this strain has a high ability to metabolize date juice. The data on optimization of physiological conditions of fermentation, pH, temperature, inoculum's size, glucose and nitrogen concentration showed that the maximum xanthan yield of 24.5 g/L was obtained from 60 g/L glucose, 3 g/L ammonium sulphate when batch fermentation was carried with 5% inoculum's size at pH 7, 28C, 48 h, on a rotary orbital shaker at 180 rpm. The polysaccharide purified by high performance liquid chromatography and analyzed by thin layer chromatography contained glucose, glucoronic acid and mannose.

PRACTICAL APPLICATIONS

Agri‐food by‐products rich in sugars may be used to produce high added value food ingredients such as xanthan gum. No work has studied the production of this polysaccharide from date. This study is focused on given value addition to date by‐product (hard texture) by production of xanthan gum. The effect of several parameters (pH, temperature, inoculum's size, agitation speed, nitrogen source and carbon concentration) on production yield was investigated.
Treatment Of Dens Invaginatus In Supernumerary Teeth
Authors: Neto Manoel D. Sousa , Paiva Eduardo Petersen , Saquy Paulo Cesar , Pécora Jesus D.
Published: February 2010

The endodontic treatment and aesthetic restoration of a case of Oehlers Type I dens invaginatus in supernumerary teeth is presented.
Part 2: Odontogenic Sinus Disease And Elective Clinical Procedures Involving The Maxillary Antrum: Diagnosis And Management
Authors: Sandler Howard J.
Published: February 2010

Although odontogenic sinusitis is a rare entity when compared to sinus disease of rhinogenic origin, it is extremely important to identify a dental aetiology when it occurs. The offending tooth or teeth would thus require endodontic treatment or extraction, and the sinus disease carefully assessed and appropriately managed. Aetiology and presentation of oro‐antral fistulae are also discussed and guidelines for the management of this complication are recommended. Certain lesions such as cysts and tumours may involve the jaws and hence the maxillary antrum; some of these, such as a radicular cyst are quite common, but the rarer ones are included for completeness. Surgical techniques are continuously evolving to optimise form and function of the jaws, and when applied to the maxilla there may be some impact on nasal and sinus function. The advent, and now proven success, of osseointegrated jaw implants have brought with them innovations and refinements of bone grafting techniques, and more recently distraction osteogenesis for augmentation. Maxillary osteotomies for surgical orthodontics, and to facilitate prosthodontic treatment are briefly mentioned, as most of these inevitably involve the antrum and/or nose.

This paper discusses, in summary form, important aspects of clinical dental practice which may involve the maxillary antrum. It is thus a broad overview of certain pathologic conditions and elective surgical procedures which have relevance to both medical and dental practitioners.
Inappropriate Treatment Of Traumatic Dental Injuries
Authors: Dorney Brett
Published: February 2010

Traumatic dental injuries are emergencies that must be treated expediently and efficiently to reduce pain and to restore function and appearance. With an increase in the incidence of traumatic dental injuries in our community (1) it is essential that the dental practitioner has “up‐to‐date” knowledge of dental trauma. The peak incidences of injury are 2–4 years and 8–10 years of age, with statistics revealing 30% of children suffer trauma to the primary dentition, and 22% of children suffer trauma to the permanent dentition by the age of 14(1). The male to female ratio is 2:1. Aside from the emergency treatment and clinical decisions that must be made at the time of injury there is a need for long‐term follow‐up because of the high incidences of complications (2, 3).

The factors that will influence the extent of injury will be energy impact, the direction of the impacting object, its shape and its resilience (4). Recent articles have raised concerns about inappropriate treatment for traumatic dental injuries (5, 6). This report will look at one such case.
Clinical Judgement And Decision Making In Endodontics
Authors: Messer Harold H.
Published: February 2010

Clinical judgement in endodontics consists of much more than diagnosis and treatment planning for the affected tooth. The issues involved in clinical judgement and decision making can be summarised by three questions:

Is endodontic treatment appropriate for the patient? Endodontic treatment should be undertaken only as part of an agreed, comprehensive treatment plan that takes into account patient concerns as well as objective clinical findings.

How difficult is the endodontic treatment? The difficulty of the case should be balanced with the skill and experience of the dentist, in deciding whether to manage the case in general practice or to refer the patient to an endodontist. The use of a standard form for assessing the difficulty of each endodontic case will aid in consistent, systematic assessment of patients. An example of such a form is provided.

What is the prognosis for the tooth? The outcome of endodontic treatment depends not only on the endodontic treatment but on other factors such as restorability and periodontal status. The prognosis will be compromised by procedural problems and by restorative and periodontal factors.

In all but routine cases, the steps involved in decision making may be more complex and less easily resolved than the practical clinical aspects of endodontic therapy.
Mandibular Block Injections ‐ The Inner Game
Authors: Watson John E.
Published: February 2010

This paper is a sequel to a previous article published in the April 1998 issue of this journal (I). Whereas the earlier work concentrated largely on the anatomy and geometry of the Gow‐Gates block, the present paper is more directed towards the mental barriers encountered when a clinician is confronted by a whole new set of conceptual demands. Paradoxically, the concepts underlying the Gow‐Gates technique are almost diametrically opposite to what has traditionally been taught in dental schools in relation to the inferior alveolar nerve block. The author's central hypothesis is that the explanation for indifferent results experienced by dentists in their first attempts at the Gow‐Gates technique lies primarily in mindsets acquired from experience with the inferior alveolar block. It is suggested that the subconscious mind can be as powerful a determinant of human behaviour as the conscious mind, a position more in line with the findings of Freud and Jung than with the cognitivist vogue enthusiastically embraced by contemporary academic psychologists. It is further postulated that the subconscious is amenable to conscious guidance, a skill that can be enhanced by practice.
Neuropathic Orofacial Pain Part 2–Diagnostic Procedures, Treatment Guidelines And Case Reports
Authors: Vickers E. Russell , Cousins Michael J.
Published: February 2010

Neuropathic orofacial pain can be difficult to diagnose because of the lack of clinical and radiographic abnormalities. Further difficulties arise if the patient exhibits significant distress and is a poor historian regarding previous diagnostic tests and treatments, such as somatosensory local anaesthetic blockade. Valuable information can be obtained by utilising the McGill Pain Questionnaire that allows the patient to choose words that describe the qualities of his/her pain in a number of important dimensions (sensory and affective). Basal pain intensity should be measured with the visual analogue scale, a simple instrument that can evaluate the efficacy of subsequent treatments. The dentist or endodontist can employ sequential analgesic blockade with topical anaesthetics and perineural administration of plain local anaesthetic to ascertain sites of neuropathology in the PNS. These can be performed in the dental chair and in a patient blinded manner. Other, more specific, tests necessitate referral to a specialist anaesthetist at a multidisciplinary pain clinic. These tests include placebo controlled lignocaine infusions for assessing neuropathic pain, and placebo controlled phentolamine infusions for sympathetically maintained pain.

The treatment/management of neuropathic pain is multidisciplinary. Medication rationalisation utilises first‐line antineuropathic drugs including tricyclic antidepressants such as amitriptyline and nortriptyline, and possibly an anticonvulsant such as carbamazepine, sodium valproate, or gabapentin if there are sharp, shooting qualities to the pain. Mexiletine, an antiarrhythmic agent and lignocaine analogue, may be considered following a positive patient response to a lignocaine infusion. All drugs need to be titrated to achieve maximum therapeutic effect and minimum side effects. Topical applications of capsaicin to the gingivae and oral mucosa are a simple and effective treatment in two out of three patients suffering from neuropathic orofacial pain. Temporomandibular disorder is present in two thirds of patients and should be assessed and treated with physiotherapy and where appropriate, occlusal splint therapy. Attention to the patient's psychological status is crucial and requires the skill of a clinical psychologist and/or psychiatrist with pain clinic experience. Psychological variables include distress, depression, expectations of treatment, motivation to improve, and background environmental factors. Unnecessary dental treatment to “remove the pain” with dental extractions is contraindicated and aggravates neuropathic orofacial pain.
An Assessment Of Techniques For Dehydrating Root Canals Using Infrared Laser Radiation
Authors: Amyra T. , Walsh L.T.
Published: February 2010

Infrared lasers have been used for debridement and sterilisation of both soft and hard tissues, but there have been few studies of such laser applications in endodontics. The present laboratory study was undertaken to examine the feasibility of using pulsed infrared laser radiation to remove moisture from root canals (with an adjunctive sterilising effect). Canals were prepared in extracted teeth and a standardised technique used to fill the apical half of the root canal with saline. Pulses of CO2 or Nd:YAG laser energy were delivered into the root canal system via miniature applicators and residual fluid determined, as well as temperature changes on the root surface. With the CO2 laser, long pulse durations were effective at dehydrating the canals, but elicited deleterious thermal changes both locally within the canal as well as on the root surface. With Nd:YAG laser treatment, large temperature increases on the root surface occurred even with low powers and low pulse frequencies, and extended times were necessary for dehydration. With higher powers and pulse frequencies, complete dehydration could be achieved in less than 60 seconds, however root surface temperatures increased approximately 25 degrees, and the radicular dentine was damaged by the production of plasma. Dehydration of root canals could not be achieved safely with these two infrared lasers, and damage to both radicular dentine and the periodontal ligament would occur if these techniques were to be applied clinically. Alternative methods which do not exert significant thermal effects should be investigated.
Bacterial Contamination Of Cracks In Symptomatic Vital Teeth
Authors: Kahler Bill , Moule Alex , Stenzel Deb
Published: February 2010

As part of an ongoing study on the initiation of cracks in teeth, 20 teeth exhibiting symptoms consistent with the presence of dentinal cracks were examined. The presence of a cracked cusp was confirmed by the selective application of pressure either with a mirror handle or Fracfinder (Svenoka, Dental Instruments, Vasby, Sweden). Cracked cusps were fractured from the teeth after the removal of all existing restorations and were immediately placed into ten percent formalin. Subsequently, specimens were dehydrated, sputter‐coated and examined under the scanning electron microscope (SEM). All the cracked cusps exhibited complete fracture of the dentine to the level of the dentino‐enamel junction. No partial fractures were seen. Numerous bacteria of many morphological forms were present on the dentinal surfaces, of all fractured cusps, in all teeth. Cocci, bacilli and filamentous forms were consistently found. Many bacteria were in the process of division. While bacterial contamination of dentinal cracks has been described in histological studies, the nature and distribution of these bacterial and fungal forms has not been shown previously in any detail. Prior SEM studies investigating the nature and mechanisms of fracture have not revealed bacterial contamination of the fractured surface. This paper draws attention to the fact that all symptomatic cracks in teeth appear to I. extend right through the dentine to the dentino‐enamel junction, and 2. appear to be extensively contaminated by bacteria.
Study Of Dentinal Tubule Architecture Of Permanent Upper Premolars: Evaluation By SEM
Authors: Ponce Elías Harrán , Sahli Carlos Canalda , Fernandez José Antonio Vilar
Published: February 2010

Dentinal tubules are the means by which the pulp and mineralised tissues surrounding the dentine (enamel and cementum) communicate. Through these tubules external agents can damage the pulp and subsequently the periodontal ligament. Given the importance of dentinal tubules, the authors evaluated the numerical density, shape, and individual surface area of tubule openings and the percentage of dentine occupied by these. Eight permanent upper premolars were studied using scanning electron microscopy (SEM).

In the crown, the external surface of the dentine was evaluated at the dentino‐enamel junction and the internal surface at the pulp chamber wall. At the cervical, middle and apical thirds of the root, the external surface was evaluated at the cemento‐dentinal junction and the internal surface at the root canal wall.

The results showed that numerical density of tubule openings is significantly greater (p < 0.05) at the cervical third of the dentine, at its junction with the cementum and at the pulpal chamber wall, with respect to other areas evaluated. The individual surface area of each opening varied from 5.72 μm2 in the dentine of the pulpal chamber wall to 0.97 μm2 in the dentine of the apical third of the root canal wall. The percentage of area occupied by the dentinal tubules per mm2 of dentine was significantly higher (p < 0.01) at the internal dentinal surface as compared to the external. The shape of the tubule openings was found to be circular in the crown and became more irregular as the apical third of the root was approached.
Anatomical Variation Of The Sphenomandibular Ligament
Authors: Garg Ankit , Townsend Grant
Published: February 2010

The sphenomandibular ligament, which is derived from the sheath of Meckel's cartilage, is a fibrous structure that passes between the spine of the sphenoid bone and the lingula of the mandible. Although anatomical texts provide basic descriptions of this structure, there are few published reports of the extent of its variability or its possible clinical implications. The aim of this study was to provide a detailed description of the nature and extent of anatomical variability in the sphenomandibular ligament of seven human cadavers. Dissections of sagittally sectioned heads were performed using a medial approach that involved displacement of the tongue and mucosal tissues in the oral cavity and oropharynx, then reflection of the medial pterygoid muscle.

The ligaments ranged in shape from thin bands that descended for a short distance from the spine of the sphenoid to broad bi‐concave ligaments with prominent insertions. The mylohyoid nerve was seen to pass behind the ligament in all specimens, emerging from the postero‐inferior border of the mandibular attachment before running into the mylohyoid groove on the medial surface of the ramus. Lying in the pterygomandibular space, the ligament was surrounded by fascia, both structures presenting potential barriers to the diffusion of local anaesthetic solution if injected medially. The appearance of the lingula also varied, and did not seem to reflect the size of attachment of the ligament, suggesting an alternative explanation of lingula morphology, perhaps related to a continuation of the mylohyoid ridge and anterior border of the mylohyoid groove.
Conservative Management Of An Intruded Immature Maxillary Permanent Central Incisor With Healing Complication Of Pulp Bone
Authors: Roberts Jemima , Olsen Christopher , Messer Harold
Published: February 2010

Traumatic intrusion injury of permanent teeth is serious with multiple complications possible associated with the pulp, periodontal ligament, alveolar bone and Hertwig's epithelial root sheath. The optimal treatment for the management of an intrusion injury has not yet been determined. A case is presented involving the conservative management of an immature maxillary permanent central incisor intrusively luxated by allowing for re‐eruption and orthodontic extrusion two weeks later. After a follow‐up period of ten months, the intruded tooth continued to show a mobility of grade one, without metallic percussion tone or infra‐occlusion, which confirmed periodontal ligament healing. Although the intruded tooth failed to respond to dry ice testing, no other signs of pulp necrosis were evident and the colour of the intruded tooth was within normal limits throughout the follow‐up period. However, complications of healing of Hertwig's epithelial root sheath occurred, causing in‐growth of bone and periodontal ligament into the root canal.
Advantages And Disadvantages Of New Torque‐Controlled Endodontic Motors And Low‐Torque NiTi Rotary Instrumentation
Authors: Gambarini Gianluca
Published: February 2010

The main problem with the NiTi rotary instrumentation technique is instrument failure. During shaping procedures, rotary instruments might lock and/or screw into canals and, consequently, be subjected to high levels of stress. This may frequently lead to instrument separation or deformation. If a high‐torque motor is used, the applied forces are usually very high and the instrument‐fracture limit is often exceeded, thus increasing the risk of intracanal failure. A possible solution of this problem is to use a low‐torque endodontic motor, which operates below the maximum permissible torque limit of each and every rotary instrument. During clinical instrumentation of root canals, if a torque‐controlled motor is loaded right up to the instrument‐specific torque, the motor stops momentarily and/or starts rotating counter‐clockwise (auto‐reverse function) to disengage the locked instrument. These safety mechanisms were developed to reduce the risk of instrument fracture. The author fully discusses the rationale for selecting lower torque values in everyday endodontic practice, and provides clinicians with useful information on the advantages and disadvantages of new endodontic motors with torque control.
The Quality Of Clinical Fit Of Stainless Steel Bands Used In Endodontics
Authors: Pane E.S. , Messer Harold H.
Published: February 2010

Stainless steel bands are commonly advocated to protect posterior teeth against fracture during endodontic treatment and before final restoration. A poorly fitting band, however, may lead to a compromised coronal seal and gingival irritation. This radiographic study assessed the quality of fit and marginal adaptation in the proximal area of stainless steel bands placed during routine endodontic treatment.

Clinical radiographs of 120 maxillary and mandibular premolars and molars were evaluated. All radiographs were taken during routine clinical endodontic treatment and randomly selected from cases completed by ten operators. Approximately one‐half of cases did not meet the criteria of adequate marginal seal (mesial: 65/120; distal: 49/120). Only 11 teeth were found to have adequate fit of the band on both mesial and distal aspects of the tooth. The most common reason for inadequacy of fit was lack of band adaptation to the tooth contour in the cervical region. Stainless steel bands have a high possibility of poor marginal fit and should be used with the awareness that they may produce other clinical problems.
Pulpal Heat Changes With Newly Developed Resin Photopolymerisation Systems
Authors: Weerakoon A.T. , Meyers I.A. , Symons A.L. , Walsh L.J.
Published: February 2010

Composite resin is a widely‐used direct tooth coloured restorative material. Photoactivation of the polymerisation reaction can be achieved by visible blue light from a range of light sources, including halogen lamps, metal halide lamps, plasma arc lamps, and Light Emitting Diode (LED) lights. Concerns have been raised that curing lights may induce a temperature rise that could be detrimental to the vitality of the dental pulp during the act of photoactivation. The present study examined heat changes associated with standardised class V restorations on the buccal surface of extracted premolar teeth, using a curing time of 40 seconds. The independent effects of type of light source, resin shade, and remaining tooth thickness were assessed using a matrix experimental design. When a conventional halogen lamp, a metal halide lamp and two different LED lights were compared, it was found that both LED lamps elicited minimal thermal changes at the level of the dental pulp, whereas the halogen lamp induced greater changes, and the metal halide lamp caused the greatest thermal insult of all the light sources. These thermal changes were influenced by resin shade, with different patterns for LED versus halogen or halide sources. Thermal stress reduced as the remaining thickness of tooth structure between the pulp and the cavity floor increased. From these results, it is concluded that LED lights produce the least thermal insult during photopolymerisation of composite resins.
Proliferative Activity In Periapical Lesions
Authors: Tripi Teresa Roberta , Bonaccorso Antonio , Rapisarda Ernesto , Bartoloni Giovanni
Published: February 2010

The identification of proliferative activity in periapical lesions may be useful in discovering the biological behaviour of different cell types. Proliferant cell nuclear antigen (PCNA), Ki67, CD3 and p53 have been used for the evaluation of the proliferative ability of many lesions. In this study, 16 periapical granulomas and 8 radicular cysts were analysed. A semi‐quantitative method was used for evaluation of each lesion and antigen. According to the intensity of staining the following scores were assigned: 0 = no reactivity; 1 = reactivity above background; 2 = moderate reactivity; 3 = strong reactivity. Ki67 positive cells were present in all the periapical lesions. The antibody Ki67 was positive in pathological keratinic cells, while it was only slightly positive in normal epithelial cells. PCNA positive cells were present in 22 of the 24 cases examined. CD3 reactivity was also highly positive in periapical lesions. The reaction of oncoprotein p53 in periapical lesions was negative. The expression of the positive reaction of Ki67 and PCNA in periapical lesions is therefore an indicator of cell proliferation as a result of a chronic irritative stimulus.
The Use And Predictable Placement Of Mineral Trioxide Aggregate® In One‐Visit Apexification Cases
Authors: Steinig Torsten H. , Regan John D. , Gutmann James L.
Published: February 2010

Endodontic treatment of the pulpless tooth with an immature root apex poses a special challenge for the clinician. The main difficulty encountered is the lack of an apical stop against which to compact an interim dressing of calcium hydroxide (Ca(OH)2), or the final obturation material. In these situations the unpredictability of the result, the difficulty in creating a leak‐proof temporary restoration for the duration of treatment, and the difficulty in protecting the thin root from fracture may lead to complications when using traditional (Ca(OH)2‐based) apexiflcation techniques. Furthermore, given the increased mobility of today's society, lengthy treatment protocols are fraught with problems, and may not be followed through to completion. This may lead to ultimate failure of the case.

Mineral Trioxide Aggregate (MTA®) has recently been introduced for use in endodontics. Current literature supports its efficacy in a multitude of procedures including apexiflcation. The focus of this paper is to propose a one‐visit apexiflcation protocol with MTA® as an alternative to the traditional treatment practices with Ca(OH)2. One‐visit apexiflcation may shorten the treatment time between the patient's first appointment and the final restoration. The importance of this approach lies in the expedient cleaning and shaping of the root canal system, followed by its apical seal with a material that favours regeneration. Furthermore, the potential for fractures of immature teeth with thin roots is reduced, as a bonded core can be placed immediately within the root canal.
MTA Apexification Combined With Conventional Root Canal Retreatment
Authors: Linsuwanont Pairoj
Published: February 2010

Apexiflcation aims to induce apical closure of the open root apex with a hard‐tissue barrier, against which a root filling can be compacted. Despite the popularity of the apexification procedure, calcium hydroxide therapy has some disadvantages that include variability of treatment time, unpredictability of apical closure, difficulties with patient follow‐up and delayed treatment. Mineral trioxide aggregate (MTA) is a potential apical barrier material with good sealability and a high degree of biocompatibility. This paper demonstrates the placement of an apical barrier using MTA as an alternative to conventional long‐term calcium hydroxide therapy.
Torsional Properties Of New And Used Rotary K3 NiTi Files
Authors: Yared Ghassan , Kulkarni Gajanan K. , Ghossayn Fadia
Published: February 2010

The purpose of this study was to compare torque (gcm) and angle of rotation (degrees) at fracture of new and used NiTi K3 .04 rotary instruments. The relation between size of instrument and torque at fracture was also investigated. The torque and angle of rotation at fracture of new and used NiTi K3 .04 rotary instruments sizes 15 to 40 were determined according to ANSI/ADA Specification No. 28. Analysis of variance was used to compare the torque and angle of rotation at fracture among the different sizes of the new instruments and between new and used instruments of the same size (α = 0.05). The relationship between torque at fracture and size of instrument was determined with a regression analysis. Torque at fracture of the new instruments increased significantly with the diameter (p < 0.05). The used instruments, sizes 25 to 40, had significantly lower torque at fracture values compared to the new ones (p < 0.05). The used instruments, sizes 20 and 35 had significantly lower angle of rotation at fracture compared to the new ones (p < 0.05). A stronger relationship was found between the size of the file and the torque at fracture for the new instruments (p < 0.0001) compared to the used ones (p < 0.0001). The results of the present study suggested that the torque at fracture values of new instruments increased significantly with the diameter. The results also suggested that repeated use of .04 K3 instruments affected mainly the torque at fracture.
Carious Pulpitis: Microbiological And Histopathological Considerations
Authors: Martin F. Elizabeth
Published: February 2010

Dental caries is the result of microbial activities that induce the progressive localised destruction of teeth. Without treatment, this eventually results in infection of the dental pulp and surrounding periapical tissues. Although the bacteria responsible for caries initiation and early caries progression have been extensively studied, the microbiology of dentine caries reportedly shows considerable diversity and the associated microflora has not yet been fully identified. A search of the literature shows that few studies have analysed the microbiology of deep caries or examined the relationship between this microflora and the histopathology of chronic pulpitis in symptomatic teeth.

The majority of the studies investigating the microbiology of carious dentine have used traditional culture methodology that has been reported to be fraught with difficulties and to underestimate the microbial populations. However, recent work using new technology in the form of Polymerase Chain Reaction (PCR) has shown potential by enhancing the identification and quantification of bacteria from complex environments. Application of this technology to carious dentine has identified an environment dominated by anaerobic organisms and containing significant numbers of Gram‐negative bacteria that have been strongly implicated in endodontic infections subsequent to carious pulpitis.

Examination of the histopathology of pulp sections from teeth extracted as a result of carious pulpitis showed pulpal reactions ranging from minimal inflammation to marked inflammatory infiltration of the pulp tissue. Of interest, were hard and soft tissue pathologic changes noted in the pulp tissues resulting from the combined effects of the carious microorganisms and the host tissue response.

Improved knowledge of the microbial species associated with pulpitis could create the potential for development of diagnostic tools and restorative materials with appropriate antimicrobial properties.
Combined Endodontic And Surgical Treatment Of A Three‐rooted Maxillary First Premolar
Authors: Evans Mark
Published: February 2010

A case is reported in which endodontic treatment of a maxillary first premolar was complicated by the fact that the tooth had three roots. One of the roots was completely calcified and therefore could not be negotiated with endodontic files. There was a large periapical lesion associated with the tooth and this was surgically removed. During the surgical procedure a retrograde cavity was prepared on the calcified root using ultrasonic instruments and this was filled using Super EBA cement. Twelve months later the tooth was asymptomatic and the periapical tissues had completely healed.