JOURNAL OF TEXTURE STUDIES, Issue 3 2000
MICHIKO TOGASHI
ABSTRACT The three-dimensional movement of a tooth, any tooth, while naturally eating, was measured by an apparatus developed in our laboratory. The movement of the first molar on the usually used side is reported here. The mastication movements are divided into two parts, namely the rhythmical chewing period during which there are mastication pressure loads on the molar and the irregularly pulsated moving period in preparation for the swallowing followed by the rhythmical one during which there is no more pressure on it. The amplitudes of the up and down movements of the molar are 10,22mm for the rhythmical chewing period which are bigger than those for the irregularly moving period. The rhythmical chewing periods are distributed around 10,40 s depending on 14 kinds of food texture, and also on the size of the food, in a fairly similar manner for the participants. The period is longer for tough foods and bigger samples. The irregularly pulsated moving periods are widely distributed, 2,45s, and depend both on the food texture and on the participant. The irregular moving periods are longer for foods which scatter in the mouth or adhere to the teeth when chewing. The ingestion difficulty of the food was divided into two groups. One is where it is difficult to break down the food with the teeth and the other is where it is difficult to prepare for swallowing. [source]

THE USE OF OXYGEN ISOTOPES IN SHEEP MOLARS TO INVESTIGATE PAST HERDING PRACTICES AT THE NEOLITHIC SETTLEMENT OF ÇATALHÖYÜK, CENTRAL ANATOLIA

ARCHAEOMETRY, Issue 3 2010
E. HENTON
This paper presents a pilot study designed to test the use of oxygen isotopes for investigating aspects of early herding practices in the Neolithic of western Asia, using the site of Çatalhöyük in central Anatolia as a case study. Time-sequenced ,18O values in dental enamel of archaeological sheep are assessed for post-depositional diagenetic effects and compared with seasonal ,18O meteoric water values in the region today. The evidence is used to indicate the environmental conditions in which individual sheep spent their first year, enabling management of breeding and birthing seasons, and movement to seasonal pastures, to be investigated. [source]

The biocompatibility of modified experimental Portland cements with potential for use in dentistry

INTERNATIONAL ENDODONTIC JOURNAL, Issue 12 2008
J. Camilleri
Abstract Aim, To evaluate the biocompatibility of a group of new potential dental materials and their eluants by assessing cell viability. Methodology, Calcium sulpho-aluminate cement (CSA), calcium fluoro-aluminate cement (CFA) and glass,ionomer cement (GIC; Ketac Molar), used as the control, were tested for biocompatibility. Using a direct test method cell viability was measured quantitatively using alamarBlueÔ dye, and an indirect test method where cells were grown on material elutions and cell viability was assessed using methyltetrazolium (MTT) assay as recommended by ISO 10 993-Part 5 for in vitro testing. Statistical analysis was performed by analysis of variance and Tukey multi-comparison test method. Results, Elution collected from the prototype cements and the GIC cured for 1 and 7 days allowed high cell activity after 24 h cell exposure, which reduced after 48 h when compared to the nontoxic glass,ionomer control, but increased significantly after 72 h cell contact. Elutions collected after 28 days revealed reduced cell activity at all cell exposure times. Cells placed in direct contact with the prototype materials showed reduced cell activity when compared with the control. Conclusions, Cell growth was poor when seeded in direct contact with the prototype cements. GIC encouraged cell growth after 1 day of contact. The eluted species for all the cements tested exhibited adequate cell viability in the early ages with reduced cell activity at 28 days. Changes in the production of calcium hydroxide as a by-product of cement hydration affect the material biocompatibility adversely. [source]

Postnatal glutamate-induced central nervous system lesions alter periodontal disease susceptibility in adult Wistar rats

JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2001
Torbjørn Breivik
Abstract Background: Inability to mount a suitable brain-neuroendocrine response to bacterial or other antigenic challenges has been found to play an important rôle in infectious and inflammatory disease susceptibility and progression, including periodontal disease. Objective: The present study was designed to determine the effects of glutamate administration to new-born Wistar rats on the development and progression of naturally occurring and ligature-induced periodontal disease in the rats as adults. Postnatal glutamate administration is known to permanently damage neurones in the hypothalamic arcuate nucleus. Method: New-born rats were treated 1× daily subcutaniously with 2 mg/g of monosodium-L-glutamate (MSG) for 5 days from day 3 to 6. Control animals were injected with similar amounts of saline. Experimental ligature-induced periodontal disease was induced in the rats at the age of 12 weeks at maxillary right 2nd molar teeth. The contralateral maxillary left 2nd molars served as control teeth, and for assessment of naturally occurring periodontal disease. Disease progression was evaluated histometrically. Results: The results revealed that the glutamate-lesioned rats developed significantly more periodontal tissue destruction compared to sham-lesioned control rats in both the ligated and non-ligated teeth. Conclusions: This study supports our resent findings indicating that inappropriate brain-neuroendocrine-immune regulation may play a rôle in periodontal disease susceptibility and progression. Zusammenfassung Hintergrund: Es hatte gezeigt werden können, dass die Unfähigkeit des Gehirns auf einen bakteriellen oder antigenen Reiz mit einer angemessenen neuroendokrinen Antwort zu reagieren, eine wichtige Rolle für die Empfänglichkeit für infektiöse und entzündliche Erkrankungen einschliesslich Parodontitis spielt. Die Gabe von Glutamat nach der Geburt führt zu irreversiblen Schäden der Neurone des Nucleus arcuatus des Hypothalamus. Zielzetzung: Untersuchung der Auswirkungen von Glutamatgaben bei neugeborenen Wistar-Ratten auf die Entstehung und das Fortschreiten natürlich vorkommender und ligaturinduzierter Parodontitis im Erwachsenenalter. Material und Methoden: Bei 24 neugeborenen Wistar-Ratten wurden einmal täglich 2 mg/g L-Mononatriumglutamat und bei 20 Kontrolltieren statt dessen Kochsaltzlösung vom 4. Lebenstag an 4 Tage lang subkutan injiziert. Am rechten zweiten Oberkiefermolaren wurden bei den 12 Wochen alten Ratten eine experimentelle ligaturinduzierte Parodontitis ausgelöst. Der kontralaterale 2. Molar des Oberkiefers diente als Kontrolle und um natürlich vorkommende Parodontitis zu untersuchen. Das Fortschreiten der parodontalen Zerstörung wurde histometrisch erfasst. Ergebnisse: Die Ergebnisse zeigten, dass die Ratten mit den glutamatinduzierten Läsionen statistisch signifikant stärkere parodontale Zerstörungen sowohl an den Zähnen mit wie auch an denen ohne Ligaturen im Vergleich zur Kontrollgruppe aufwiesen. Schlussfolgerungen: Eine unangemessene neuroendokrinoimmunologische Regulation des Gehirns scheint eine Rolle bei der Empfänglichkeit für und das Fortschreiten von Parodontitis zu haben. Résumé Origine: L'incapacitéàétablir une réponse neuroendocrinienne cervicale efficace pour des défis bactériens ou antigèniques joue un rôle important dans la susceptibilité et la progression des maladies infectieuses et inflammatoires, dont les parodontites. But: Cette étude a été imaginée pour déterminer les effets de l'administration de glutamate à des rats Wistar nouveau-nés sur le développement et la progression de maladies parodontales naturelles et induites par des ligatures chez le rat adulte. On sait que l'administration de glutamate en postnatal endommage de façon permanente les neurones du noyau d'arc hypothalamique. Méthodes: Les rats nouveaus-nés furent traités une fois par jour par administration sous cutanée de 2 mg/g de monosodium-L-glutamate (MSG) pendant 5 jours. Les animaux contrôles recevaient une dose similaire de sérum physiologique. La parodontite expérimentale par ligature était réalisée à l'âge de 12 semaines, sur la deuxième molaire supérieure droite. La dent controlatérale servait de contrôle et à la mise en évidence de maladie parodontale naturelle. La progression de la maladie fut évaluée par histométrie. Résultats: Les résultats montrent que les rats atteints de lésions dues au glutamate développent plus de destructions parodontales (par ligatures ou sans ligatures) par rapport aux rats contrôles atteints de lésions simulées. Conclusion: Cette étude supporte nos récentes découvertes qui indiquent qu'une régulation immunitaire neuroendocrinienne cervicale inappropriée peut jouer un rôle dans la susceptibilité et la progression des maladies parodontales. [source]

Physical-mechanical properties of glass ionomer cements indicated for atraumatic restorative treatment

AUSTRALIAN DENTAL JOURNAL, Issue 3 2009
CC Bonifácio
Abstract Background:, This study evaluated mechanical properties of glass ionomer cements (GICs) used for atraumatic restorative treatment. Wear resistance, Knoop hardness (Kh), flexural (Fs) and compressive strength (Cs) were evaluated. The GICs used were Riva Self Cure (RVA), Fuji IX (FIX), Hi Dense (HD), Vitro Molar (VM), Maxxion R (MXR) and Ketac Molar Easymix (KME). Methods:, Wear was evaluated after 1, 4, 63 and 365 days. Two-way ANOVA and Tukey post hoc tests (P = 0.05) analysed differences in wear of the GICs and the time effect. Fs, Cs, and Kh were analysed with one-way ANOVA. Results:, The type of cement (p < 0.001) and the time (p < 0.001) had a significant effect on wear. In early-term wear and Kh, KME and FIX presented the best performance. In long-term wear, Fs and Cs, KME, FIX and HD had the best performance. Strong explanatory power between Fs and the Kh (r2 = 0.85), Cs and the Kh (r2 = 0.82), long-term wear and Fs of 24 h (r2 = 0.79) were observed. Conclusions:, The data suggested that KME and FIX presented the best in vitro performance. HD showed good results except for early-term wear. [source]

Design Strategy of Minipig Molars Using Electronic Speckle Pattern Interferometry: Comparison of Deformation under Load between the Tooth-Mandible Complex and the Isolated Tooth,

ADVANCED MATERIALS, Issue 4 2009
Netta Lev-Tov Chattah
Using electronic speckle pattern interferometry minipig molars were tested under load inside the bone socket and when embedded in a stiff polymer. It is demonstrated that the molar bends in the direction of the load in both configurations even at low loads. This shows that the intrinsic reaction of the tooth crown to load is complemented by the structures supporting the tooth. [source]

Root resorption in retained deciduous canine and molar teeth without permanent successors in patients with severe hypodontia

INTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 3 2001
K. Haselden
Aims. The ability to predict the morbidity of retained deciduous teeth with no permanent successors, a characteristic of hypodontia, would be of considerable value in treatment planning, but is hampered by lack of data. Methods. This problem was studied using 356 orthopantomogram radiographs (OPGs) from the records of 249 patients who had attended a specialist hypodontia clinic, and had retained deciduous teeth with no permanent successors. Due to their clinical importance, canine and molar teeth were chosen for examination. Resorption was assessed subjectively by three experienced clinicians. Results. Un-weighted Kappa values for reproducibility were > 0·8, and for inter-observer error 0·60,0·83. Gender related differences were minimal. Regardless of gender or radiographic age, the lower canines appear to show the least amount of resorption and the upper first molars the most. The upper and lower second molars have particularly unpredictable life spans. Whilst the lower first molars have a predictable life span that is poor, the life span for the upper first molars is slightly worse. Conclusions. Lower canines have a predictable life span that appears to be good, as do upper canines, but of lesser duration than lower canines. Molars have poorer and less predictable life spans. [source]

Loss of molars in periodontally treated patients: a retrospective analysis five years or more after active periodontal treatment

JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2006
Bettina Dannewitz
Abstract Objectives: Evaluation of tooth loss in molars and prognostic factors for molar survival. Material and Methods: Five hundred and five molars in 71 patients (mean age 46 years; 40 females) were evaluated. The following inclusion criteria were required: periodontal therapy of at least one molar, at least 5 years of supportive periodontal therapy, and baseline assessment of furcation involvement (FI). Results: At baseline 200 of 505 molars exhibited no FI, 116 degree I, 122 degree II, and 67 degree III FI. Twenty-seven molars did not receive periodontal treatment; 127 molars were subjected to non-surgical therapy, and 227 to flap surgery. Tunnel preparation was performed on 14 molars, root resection on 20, regenerative therapy on 57 teeth, and 33 molars were extracted. During the average follow-up period of 107 months 38 molars were lost additionally. Molars with degree III FI had the highest mortality. A multi-level proportional hazard model revealed smoking, baseline bone loss, number of molars left, and degree III FI as risk factors influencing the retention time of molars. Conclusion: Overall periodontal therapy results in a good prognosis of molars. Degree III FI leads to a significant deterioration of prognosis. Beyond FI smoking, baseline bone loss, and number of molars left influence molar survival. [source]

Four-Year Cost-Utility Analyses of Sealed and Nonsealed First Permanent Molars in Iowa Medicaid-Enrolled Children

JOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 4 2007
Patita Bhuridej DDS
Abstract Objectives: Dental sealants, by their ability to prevent caries and maintain teeth in better health, have some inherent utility to individuals, programs, or society. This study assessed the 4-year incremental cost utility of sealing first permanent molars of 6-year-old Iowa Medicaid enrollees from a societal perspective and identified the group of teeth or children in whom sealants are most cost effective. Methods: Dental services for first permanent molars were assessed using claims and encounter data for a group of continuously enrolled Medicaid enrollees who turned 6 between 1996 and 1999. Previously published utilities were used to weight the different health states. The weighted sum of outcomes [Quality-Adjusted Tooth-Years (QATYs)] was the measure of effectiveness. Costs and QATYs were discounted to the time of the child's sixth birthday. Results: For all first molars, the cost of treatment associated with sealed teeth was higher but the utility was also slightly higher over the 4-year period. The relative incremental cost per 0.19 QATY ratio [changing the health state from a restored tooth (utility=0.81) to a nonrestored tooth (utility =1)] by sealing the molar ranged from $36.7 to $83.5 per 0.19 QATY. The incremental cost/QATY ratio was lower for sealing lower utilizers and for mandibular versus maxillary molars. Conclusions: Sealants improved overall utility of first permanent molars after 4 years. The 4-year cost/QATY ratio of sealing the first permanent molar varied by arch and type of utilizers. Sealing first permanent molars in lower dental utilizers is the most cost-effective approach for prioritizing limited resources. [source]

Dental caries in a Portuguese identified skeletal sample from the late 19th and early 20th centuries

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009
Sofia N. Wasterlain
Abstract Dental caries was investigated in 600 adult dentitions belonging to the identified osteological collections of the Museum of Anthropology, University of Coimbra, Portugal (late 19th/early 20th centuries). The main advantage of this sample compared to an archaeological source is the presence of known demographic parameters such as age, sex, and occupation. The aim of this study is to investigate the issues involved in comparing caries data derived from archaeological death assemblages with statistics compiled from clinical studies of the living. When only the upper dentition was considered, higher rates were observed in females than in males. No differences were found between sexes for lower teeth. In both sexes, both the percentage of carious teeth and the severity of lesions were found to increase with age, demonstrating that caries activity continued throughout life. The slight decrease observed for the age group 70,79 years is probably due to the increased antemortem tooth loss in the elderly. Caries was most common at contact areas (32.9%) and rarest at smooth crown surfaces (6.5%). Root surface caries was graphed in relation to the exposure of roots, and it was confirmed that the degree of root exposure was not strongly related to the frequency of carious lesions on the exposed root surface, although both increased with age. Molars were attacked more frequently by caries as a whole than premolars, canines or incisors. The results are similar to studies of recent living populations with a limited access to professional dental care. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source]

The three-dimension finite element analysis of stress in posterior tooth residual root restored with postcore crown

DENTAL TRAUMATOLOGY, Issue 1 2010
Gang Fu
Some researchers have analyzed the stress of the anterior teeth after postcore crown restoration, but the stress of the posterior teeth after such restoration has not been reported. We used three-dimension finite element methods to analyze the stress magnitude and distribution of remaining dentin in posterior tooth residual root restored with postcore crown. The binding material, loading direction, number, length and material of posts were studied. Methods:, The models of residual root of maxillary first molar restored with postcore crown were created by CT scanning, mimics software and abaqus software. Different number, length and material of posts were used in the modeling. The posts were cemented with zinc-phosphate cement or composited resin. A load of 240 N was applied to the occlusal surface in four directions and tensile, shear, and von Mises stresses were calculated. Result:, (i) The maximum stress on remaining dentin changed irregularly as the number and length of posts changed. (ii) The maximum stress on remaining dentin decreased slightly as elastic modulus of the material of posts increased. (iii) The maximum stress on bonding layer and remaining dentin was lower when bonded with resin luting agent than with zinc-phosphate cement. (iv) The maximum stress on remaining dentin increased markedly as loading angle increased. Conclusion:, The number, length, material of posts, bonding material and loading angle all have influence on the magnitude and distribution of stress. The influence of loading angle is most apparent. [source]

Crown-root fracture of a lower first primary molar: report of an unusual case

DENTAL TRAUMATOLOGY, Issue 3 2008
Gabriela da Rosa Götze
Abstract,,, Dental traumas are highly prevalent lesions in primary teeth, but crown-root fractures are seldom observed in posterior teeth of this dentition. The aim of the present report was to describe the diagnosis, treatment, and a 24-month follow-up of an unusual case of complicated crown-root fracture in a lower first primary molar of a 3-year-old boy. [source]

Dislocation of an upper third molar into the maxillary sinus after a severe trauma: a case report

DENTAL TRAUMATOLOGY, Issue 3 2007
Heng-Xing Cai
Abstract , Dental injuries are common following facial trauma. This article presents a rare injury: the dislocation of a third molar into the maxillary sinus after complex mandibular and maxillary tuberosity fractures. The possible mechanism and clinical treatment are discussed. [source]

Analysis of 154 cases of teeth with cracks

DENTAL TRAUMATOLOGY, Issue 3 2006
Byoung-Duck Roh
Abstract,,, It is well known that cracked teeth occur most frequently in the mandibular molars with large or poor restorations, in those over 50 years of age. However, with increasing knowledge and experience with cracks of teeth, cracks appear to be found frequently in intact teeth without restorations. The aim of this study is to analyze the cases of tooth cracks in a dental hospital in a year, and to find out the characteristic features of cracks of teeth. For 1 year, each tooth that were identified as a cracked tooth was recorded and analyzed in terms of the classification of cavity and restorative material, the nature of opposing tooth, the location in the arch, the age and gender, and the clinical signs and symptoms, and treatment result. Cracked teeth were observed most frequently in the teeth with no restorations (60.4%) and with class I restorations (29.2%). The most prevalent age was in those over 40 years of age (31.2% in their 40s, 26.6% in their 50s) and the prevalence was similar in men (53.9%) and women (46.1%). Cracked teeth were found most frequently in the maxillary molars (33.8% in first molar, 23.4% in second molar) than in the mandibular molars (20.1% in first molar, 16.2% in second molar). 96.1% of the cracked teeth responded to the bite test, and 81.1% of the cracked teeth were observed in the mesiodistal direction. The prevalence of cracked tooth was highest in the intact teeth with no restoration, in maxillary molars, and in those over 40 years of age. When examining a intact maxillary posterior tooth that is sensitive to a bite and thermal change, crack in the mesiodistal direction need to be considered one of the causes. [source]

Xenoestrogenic gene exression: Structural features of active polycyclic aromatic hydrocarbons

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2002
T. Wayne Schultz
Abstract Estrogenicity was assessed using the Saccharomyces cerevisiae -based Lac-Z reporter assay and was reported as the logarithm of the inverse of the 50% molar ,-galactosidase activity (log[EC50,1]). In an effort to quantify the relationship between molecular structure of polycyclic aromatic hydrocarbons (PAHs) and estrogenic gene expression, a series of PAHs were evaluated. With noted exceptions, the results of these studies indicate that the initial two-dimensional structural warning for estrogenicity, the superpositioning of a hydroxylated aromatic system on the phenolic A-ring of 17-,-estradiol, can be extended to the PAHs. This two-dimensional-alignment criterion correctly identified estrogenicity of 22 of the 29 PAHs evaluated. Moreover, the estrogenic potency of these compounds was directly related to the size of the hydrophobic backbone. The seven compounds classified incorrectly by this structural feature were either dihydroxylated naphthalenes or aromatic nitrogen-heterocyclic compounds; all such compounds were false positives. Results with dihydroxylated naphthalenes reveal derivatives that were nonestrogenic when superimposed on the phenolic A-ring of 17-,-estradiol had the second hydroxyl group in the position of the C-ring or were catechol-like in structure. Structural alerts for nitrogen-heterocyclic compounds must take into account the position of the hydroxyl group and the in-ring nitrogen atom; compounds with the hydroxyl group and nitrogen atom involved with the same ring were observed to be nonactive. [source]

Reduced growth hormone receptor immunoreactivity in osteoclasts adjacent to the erupting molar in the incisor-absent (osteopetrotic) rat

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2003
Anne L. Symons
First molars fail to erupt in the incisor-absent (ia/ia) rat because of a defect in osteoclast function. Growth factors that regulate local bone metabolism include growth hormone (GH), insulin-like growth factor-I (IGF-I), epidermal growth factor (EGF) and interleukin-1 alpha (IL- 1,). Since osteoclast function may be affected by these factors, the aim of this study was to determine the distribution of GH receptor (GHr), IGF-I, EGF and IL-1,, in osteoclasts located occlusal to the erupting first molar, in the ,eruption pathway', in normal and ia/ia rats. Sagittal sections of the first molar and adjacent bone from 3- and 9-d-old animals were examined. Osteoclasts were identified using tartrate-resistant acid phosphatase (TRAP). The TRAP-positive osteoclast cell numbers were higher in ia/ia animals at 3 and 9 days-of-age. In the ia/ia group, fewer osteoclasts were GHr- and IGF-I-positive at 3 d of age, and at 9 d of age fewer osteoclasts were GHr-positive. In the ia/ia rat, defective osteoclast function failed to resorb bone to provide an eruption pathway for the lower first molar. The expression of GHr, and to some degree IGF-I, by these osteoclasts was reduced, which may be related to their ability to differentiate and function. [source]

Effect of selected literature on dentists' decisions to remove asymptomatic, impacted lower third molars

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2002
Wil J. M. Van Der Sanden
The aim of this study was to assess the effect of studying selected literature on dentists' decisions to remove asymptomatic, impacted lower third molars. A pre-test,post-test control group design was used. Given 36 patient cases, two groups of 16 general dental practitioners each were asked to assess the need for removal of asymptomatic impacted lower third molars. The cases were classified by three parameters: ,position of the third molar', ,impaction type', and ,patient age'. After studying selected literature on this subject by the intervention group, both groups were asked to assess the same cases again. Frequencies of decisions to remove the third molars were calculated. For each participant, tables were composed by crosstabulating the indication to remove a third molar with each of the three parameters. T -tests were used to test the significance of the difference between pre-test and post-test decisions. The overall number of indications to remove asymptomatic, impacted lower third molars decreased by 37% in the intervention group. In the control group, the difference between pre- and post-test was not statistically significant. It was concluded that the provision of selected literature significantly influences treatment decision making by dentists in a third molar decision task. [source]

Factors influencing proximal dental contact strengths

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2000
Christof E. Dörfer
The aim of this study was to systematically measure proximal contact strength in complete natural dentitions of 30 adults (25.3±3.0 years of age), and to analyze its relationship to tooth type, tooth location, chewing effort and time of day variation. The contact strengths were measured dynamically during removal of a calibrated 0.05-mm-thick metal strip between the proximal contacts of adjacent teeth. Proximal contact strengths were lower in the maxilla (2.51±1.36 N) compared to the mandible (4.26±1.88 N). Within the jaws, the lowest proximal contact strength was measured between canine and first premolar (2.91±1.79 N) and the highest between second premolar and first molar (3.73±1.95 N). Chewing increased the proximal contact strength within the maxilla (before: 2.51±1.36 N, after: 3.02±1.45 N) but it remained unchanged in the mandible (before: 4.26±1.88 N, after: 4.22±1.85 N). The proximal contact strength increased significantly from morning (3.39±1.86 N) to noon (3.61±1.77 N), and then decreased in the afternoon (3.43±1.60 N). It was concluded that proximal contact strength can be significantly influenced by location, tooth type, chewing and time of day variation. Based on the differences in distribution due to the effect of chewing and time of day, it is speculated that proximal contact strength is a physiological entity of multifactorial origin. [source]

Original article: Effect of flask closure method and post-pressing time on the upper denture base adaptation

GERODONTOLOGY, Issue 3 2010
Andréa F. Lira
doi:10.1111/j.1741-2358.2009.00307.x Effect of flask closure method and post-pressing time on the upper denture base adaptation Objectives:, The purpose of this study was to evaluate the effect of flask-closure methods, post-pressing times and acrylic resins on denture base adaptation. Materials and methods:, The resins were flasked using a hydraulic press and closed with the traditional clamp or RS system. Conventional heat-cure resin was polymerised immediately or at 6 h post-pressing at 74°C for 9 h. Rapid cycle heat-cure resin was polymerised in boiling water for 20 min. After cooling, the bases were deflasked and the sets of cast-base transversally sectioned in the regions distal to the canine, mesial to the first molar and in the posterior palatal zone. The adaptation was measured with an optical microscope (0.0005 mm) at five reference points for each section. Data were analysed using anova and Tukey's test (, = 0.05). Results:, Traditional clamp and immediate post-pressing time improved base adaptation for conventional heat-cure resin. Both post-pressing times showed most accurate base adaptation for conventional heat-cure resin when the traditional clamp was used. Immediate post-pressing time improved base adaptation for conventional heat-cure resin and the 6-h delay in time was significant for the rapid cycle heat-cure resin. Conclusions:, Traditional clamp and immediate post-pressing time improved base adaptation for conventional heat-cure resin. [source]

Calcifying epithelial odontogenic (Pindborg) tumor with malignant transformation and metastatic spread

HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 8 2001
Michael J. Veness MB
Abstract Background Pindborg tumors (calcifying epithelial odontogenic tumors) are uncommon neoplasms of odontogenic origin most often located in the posterior mandible. First described in detail in 1955 by Pindborg, these tumors are considered benign but can be locally aggressive in nature, with recurrence rates of 10% to 15% reported. The malignant form of this tumor is exceedingly rare. Methods We describe the case of a 64-year-old woman initially treated for a painful infected left mandibular third molar. The patient underwent extraction of the tooth and excision of an associated soft tissue component. Subsequent histologic review identified a Pindborg tumor of the left posterior mandible. Results After initial excision, this tumor recurred twice, with the recurrences exhibiting a progression to a malignant Pindborg tumor (odontogenic carcinoma) with vascular invasion and spread to a cervical lymph node. Further treatment involved radical surgery and adjuvant radiotherapy. At last review 12 months after treatment, the patient was disease free. Conclusions This article describes only the second case of odontogenic carcinoma. The transformation from benign to malignant histologic findings has not previously been documented in this tumor. The salient clinical features of this case are presented along with supportive pathologic and radiologic evidence. © 2001 John Wiley & Sons, Inc. Head Neck 23: 692,696, 2001. [source]

Apical surgery of a maxillary molar creating a maxillary sinus window using ultrasonics: a clinical case

INTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2010
B. García
García B, Peñarrocha M, Peñarrocha MA, von Arx T. Apical surgery of a maxillary molar creating a maxillary sinus window using ultrasonics: a clinical case. International Endodontic Journal, 43, 1054,1061, 2010. Abstract Aim, To describe a method of carrying out apical surgery of a maxillary molar using ultrasonics to create a lateral sinus window into the maxillary sinus and an endoscope to enhance visibility during surgery. Summary, A 37-year-old female patient presented with tenderness to percussion of the maxillary second right molar. Root canal treatment had been undertaken, and the tooth restored with a metal-ceramic crown. Radiological examination revealed an apical radiolucency in close proximity to the maxillary sinus. Apical surgery of the molar was performed through the maxillary sinus, using ultrasonics for the osteotomy, creating a window in the lateral wall of the maxillary sinus. During surgery, the lining of the sinus was exposed and elevated without perforation. The root-end was resected using a round tungsten carbide drill, and the root-end cavity was prepared with ultrasonic retrotips. Root-end filling was accomplished with MTA®. An endoscope was used to examine the cut root face, the prepared cavity and the root-end filling. No intraoperative or postoperative complications were observed. At the 12-month follow-up, the tooth had no clinical signs or symptoms, and the radiograph demonstrated progressing resolution of the radiolucency. Key learning points ,,When conventional root canal retreatment cannot be performed or has failed, apical surgery may be considered, even in maxillary molars with roots in close proximity to the maxillary sinus. ,,Ultrasonic sinus window preparation allows more control and can minimize perforation of the sinus membrane when compared with conventional rotary drilling techniques. ,,The endoscope enhances visibility during endodontic surgery, thus improving the quality of the case. [source]

Critical role of NFATc1 in periapical lesions

INTERNATIONAL ENDODONTIC JOURNAL, Issue 2 2010
C. Zhang
Zhang C, Yang L, Peng B. Critical role of NFATc1 in periapical lesions. International Endodontic Journal, 43, 109,114, 2010. Abstract Aim, To observe NFATc1 expression in experimental periapical lesions in rats. Methodology, Apical periodontitis was induced in Wistar rats by occlusal pulp exposure in mandibular first molar teeth. After exposure, 30 rats were killed on days 0, 7, 14, 21 and 28. The jaws that contained the first molar were removed and prepared for histological examination, immunohistochemistry and enzyme histochemistry. Results, From day 0 to day 28, the areas of periapical bone loss and the number of NFATc1-positive cells increased, peaking on day 28. The number of TRAP-positive cells increased substantially from day 0 to day 14 and then gradually decreased from day 14 to day 28. Conclusions, NFATc1 was detected and possibly involved in the inflammatory response and bone resorption of periapical tissues, as well as being associated with periapical lesion pathogenesis. [source]

Investigation of the root canal configuration of mandibular first molars in a Taiwan Chinese population

INTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2009
G. Chen
Abstract Aim, To investigate the root form and canal morphology of mandibular first molar teeth in a Taiwan Chinese population. Methodology, A total of 183 mandibular first molars were collected and examined visually through a dissecting microscope after rendering the teeth transparent. The number of roots, number of canals and canal configuration were recorded. The root canal morphology was categorized and compared according to Vertucci (1984). Results, Overall 46% of the mandibular first molars had four canals and 20% had extra-distal roots (distolingual root). In addition, 97% of the specimens had two mesial canals and 46% had two distal canals. In total, 68% of teeth with two mesial canals had two separated apical foramina, and 33% of teeth with two distal canals had two apical foramina. The most common canal configurations (Vertucci, 1984) of mesial roots were type 4 (46%) and type 2 (23%). Type 1 was encountered in 54% of the distal roots. Conclusions, The frequency of the extra-distal root on the mandibular first molar was 20%, and the incidence of three canals (Vertucci's type 8 classification) with separate apical foramina at the apex of the mesial root was 6%. The three-rooted variation of the mandibular first molar appears to be a genetic characteristic of an Asiatic racial background. [source]

Toothache referred from auriculotemporal neuralgia: case report

INTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2009
R. A. Murayama
Abstract Aim, To present a 52-year-old male patient who complained of intense pain of short duration in the region of the left external ear and in the ipsilateral maxillary second molar that was relieved by blockade of the auriculotemporal nerve in the infratemporal fossa. Summary, Extra- and intraoral physical examination revealed a trigger point that reproduced the symptoms upon finger pressure in the ipsilateral auriculotemporal nerve and in the outer auricular pavilion. The patient's medical history was unremarkable. The maxillary left second molar tooth was not responsive to pulp sensitivity testing and there was no pain upon percussion or palpation of the buccal sulcus. Periapical radiographs revealed a satisfactory root filling in the maxillary left second molar. On the basis of the clinical signs and symptoms, the auriculotemporal was blocked with 0.5 mL 2% lidocaine and 0.5 mL of a suspension containing dexamethasone acetate (8 mg mL,1) and dexamethasone disodium sulfate (2 mg mL,1), with full remission of pain 6 months later. The diagnosis was auriculotemporal neuralgia. Key learning point ,,Auriculotemporal neuralgia should be considered as a possible cause of nonodontogenic toothache and thus included in the differential diagnoses. ,,The blockade of the auriculotemporal nerve in the infratemporal fossa is diagnostic and therapeutic. It can be achieved with a solution of lidocaine and dexamethasone. [source]

A novel technique for the removal of fractured instruments in the apical third of curved root canals

INTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2009
M. Rahimi
Abstract Aim, To report on a conservative approach for removal of a fractured file in the severely curved apical portion of the distobuccal canal of a mandibular molar. Summary, With the assistance of stainless steel hand files and a chloroform-dipped gutta-percha cone, a fractured rotary NiTi instrument was successfully removed. The use of this technique may assist in removal of loose instrument fragments that are not easily accessible to other removal techniques. Key learning points, ,,Instrument fractures do not always lead to an unfavourable prognosis and their removal from the apical third of curved canals should not be routinely attempted. ,,The case highlights that it is possible to conservatively remove loosely bound objects from the hard-to-reach areas of the root canal system. [source]

Root canal morphology of mandibular permanent molars at different ages

INTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2008
H. R. D. Peiris
Abstract Aim, To investigate differences in the root canal morphology of permanent mandibular molar teeth at various ages. Methodology, Four hundred and eighty permanent mandibular first and second molars were examined. First and second molars were divided into six and five groups, respectively, according to the age of the patient at the time of extraction. Root canal morphology was studied using a clearing technique. The canal morphology of the mesial root was classified into three stages depending on its developmental pattern. When the root canal system was completely differentiated, the canal classification and the number of lateral canals and inter-canal communications were recorded. Vertucci's classification was taken as the main reference. Canal morphology was compared amongst age groups. Results, In both first and second molars, developmental stages of canal morphology amongst age groups were significantly different (P < 0.0001). The prevalence of inter-canal communications was highly significantly different in the first (P < 0.0001) and less significant in the second molar (P < 0.05). After completion of the canal differentiation, the mesial roots of first molars had type IV and II canal forms. The majority of the mesial roots of second molars had type I and III canals. C-shaped canals were found in 3% of second molars. Conclusions, Mesial roots of first and second molars mostly had one large canal until 11 and 15 years of age, respectively. In both molars, the canal system was completely defined at 30,40 years. The prevalence of inter-canal communications was low at young and old ages but high at intermediate ages. [source]

Root and canal morphology of maxillary first and second permanent molar teeth in a Ugandan population

INTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2007
C. M. Rwenyonyi
Abstract Aim, To investigate the root and canal morphology of permanent maxillary molar teeth from a Ugandan population. Methodology, Maxillary first (n = 221) and second molar (n = 221) teeth were collected from patients attending dental clinics in Kampala. Teeth were prepared using a clearing technique: the pulp chambers were accessed and the teeth placed consecutively into 5% sodium hypochlorite, 10% nitric acid, then methyl salicylate. Indian ink was injected into the pulp chambers to demonstrate the canal system. Results, In the first molars, 95.9% of the teeth had separate roots. The mesiobuccal root was fused with the palatal root in 3% of specimens and with the distobuccal root in 0.5% of teeth. In the second molars, 86% of the teeth had separate roots. The mesiobuccal root was fused with the palatal root in 6.3% of specimens and with the distobuccal root in 6.8% of teeth. Apical deltas were more frequent in the mesiobuccal root when compared with distobuccal and palatal roots of both the first and second molars. A type I canal configuration (>75%) was the most frequent in all the roots of both the first and second molars. Canal intercommunications and lateral canals were more frequent in the mesiobuccal root when compared with other roots. Conclusions, The mesiobuccal root tended to have more variations in the canal system followed by the distobuccal root, whereas the palatal root had the least. The findings in root and canal morphology of this Ugandan population were different from previous studies, which may partly be attributed to racial differences. [source]

Percentage of filled canal area in mandibular molars after conventional root-canal instrumentation and after a noninstrumentation technique (NIT)

INTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2003
C. N. Ardila
Abstract Aim, To compare the percentage of filled canal area in mandibular molar roots after using conventional root-canal hand instrumentation or after a noninstrumentation technique (NIT). Methodology, Forty mandibular molars were used shortly after extraction. The root canals of 20 molars in the manual group were conventionally prepared using hand instruments and then filled with warm vertical compaction of gutta-percha. The 20 teeth in the second group were cleaned and obturated by NIT. In each case, the entire molar, including the crown and the roots, was embedded in an acrylic resin cylinder before NIT. Horizontal sections were cut at 2, 4, 6 and 8 mm from the apex. Images of the sections were taken using a microscope at ×40 magnification and a digital camera; the images were scanned as Tagged Image File Format (TIFF) images into a PC. The cross-sectional area of the canal with the filling materials was measured using an image analysis programme. The percentage of filled area was calculated. The difference in the percentage of filled canal area between the two groups was analysed using a Student's t -test. Results, At all levels, 93,100% of the canal area was filled in both groups. No significant difference was found between the manual technique and the NIT technique at any level (P > 0.05). Conclusions, Within the limitations of this study, following the cleaning and filling of root canals using NIT, the percentage of filled root canal was similar to that using warm vertical compaction of gutta-percha after conventional root-canal instrumentation. [source]

A six-canal maxillary first molar: case report

INTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2002
F. Maggiore
No abstract is available for this article. [source]

A pre-Columbian case of congenital syphilis from Anatolia (Nicaea, 13th century AD)

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 1 2006
Y. S. ErdalArticle first published online: 16 AUG 200
Abstract In this study, the skeleton of an approximately 15-year-old child, dating back to the Late Byzantine period (13th century AD) is examined with the aim of determining where this specimen fits in the continuing arguments on the origins of syphilis. It was unearthed during an excavation at an amphitheatre in Nicaea dating to the Roman period. The Nicaea specimen displays common symptoms found in the majority of people with congenital syphilis such as Hutchinson's incisor, mulberry molar, darkened enamel, radial scar on frontal bone, sabre tibia, syphilitic dactylitis, and gummatous and non-gummatous osteomyelitis on almost every post-cranial bone. Because of the sub-periosteal new bone formation, the medullary spaces in some long bones are narrowed or completely obliterated. These lesions, which were observed via macroscopic and radiological examination, reflect the late stages of congenital syphilis. The specimen, when examined together with increasing numbers of other finds from the Old World, contributes to the argument that venereal syphilis did exist in the Old World before 1493, and brings forward the need to revise the Columbian hypothesis, which maintains that syphilis is a new disease carried to the Old World from the New World by Columbus' crew. Copyright © 2005 John Wiley & Sons, Ltd. [source]