bluuebunny/crossref_metadata_2025 huggingface dataset:
Nature and frequency of dental wear facets in an Australian Aboriginal population
Authors: KAIDONIS J.A. , RICHARDS L.C. , TOWNSEND G.C.
Published: June 2007

The nature and frequency of dental wear facets were studied in a sample of 18‐year‐old Aborigines, 28 males and 31 females, living at Yuendumu in the Northern Territory of Australia. Facet frequencies were scored indirectly using dental models for all permanent teeth, except third molars, and evidence of non‐masticatory tooth grinding in eccentric jaw positions was also recorded. The interplay between attrition and abrasion in an individual over time was assessed by examining facet appearance on serial dental models obtained at approximately yearly intervals from 7 to 25 years of age.

Facetting was found to be a very common feature of the Aboriginal dentitions, with frequencies ranging from around 65% for pre‐molars to about 90% for molars. Evidence of extreme mandibular movement was noted in 93% of males and 100% of females. The longitudinal observations indicated that wear facet definition varied over time, apparently due to episodes of tooth grinding superimposed on continually‐acting abrasive influences.

These results show that facetting on teeth associated with extreme mandibular positions and, by inference, the related behaviour of tooth grinding or bruxism are very common features in dentitions of Australian Aboriginals living an essentially non‐industrial way of life.
Taurodontism and length of teeth in patients with oligodontia
Authors: SCHALK‐VAN DER WEIDE Y. , STEEN W.H.A. , BOSMAN F.
Published: June 2007

Taurodontism and a reduced tooth length are reported to occur in patients with oligodontia. The aim of this study was to evaluate the occurrence of these factors in Dutch patients with oligodontia.

Panoramic radiographs of 117 patients with oligodontia and 91 controls were collected. Taurodontism of the mandibular first molars was recorded and the length of cuspids, bicuspids and first molars of the mandible were measured. In patients with oligodontia 28.9% showed taurodontism of one or two mandibular first molars. The prevalence of taurodontism in normal Dutch subjects was 9.9%. No significant differences were found between the two sexes in both groups. Neither was there a significant difference in the unilateral and bilateral occurrence of taurodontism. The present findings supported the hypothesis that taurodontism may be the result of an ectodermal defect and a manifestation of developmental instability in patients with oligodontia. The length of mandibular cuspids and first molars in females were significantly reduced. In males only the lower right first molar was significantly reduced. The reduced length of the teeth may also be the result of a defect in ectodermal cells. Both taurodontism and a reduced length are of importance considering dental therapy.
Reproducibility of tooth tapping rhythm in young and elderly dentate subjects
Authors: NAGASAWA T. , YUASA Y. , TSUGA K. , TSURU H.
Published: June 2007

The reproducibility of tooth tapping frequencies was measured in young and elderly dentate subjects. Six rates of tapping, i.e. 40, 60, 90, 120, 160 and 200 times per min, were practised to the accompaniment of a metronome for 15s before recording. After a 15‐s break, subjects were asked to reproduce the same rate of tapping without metronome accompaniment, and these movements were recorded. It was determined that the young subjects regulated tooth tapping frequencies by controlling velocity of mandibular movement. On the other hand, the elderly subjects regulated tooth tapping frequency by controlling opening width.
Therapeutic effects of the plane occlusal splint on signs and symptoms of craniomandibular disorders in patients with nocturnal bruxism
Authors: SHEIKHOLESLAM A. , HOLMGREN K. , RIISE C.
Published: June 2007

The long‐term effects were studied of a full arch maxillary plane occlusal splint on chronic signs and symptoms of craniomandibular disorders (CMD) in 31 patients with nocturnal bruxism. The results revealed that the score and intensity of signs and symptoms in this type of patient fluctuate from day to day and even within a single day. In spite of continuation of nocturnal bruxism, the symptoms of CMD were cured or improved with the long‐term use of the occlusal splint. However, in general, the symptoms recurred after discontinuation of splint therapy. The therapeutic mechanisms of the splint during sleep are discussed.
Accuracy of models for indirect posterior restorations
Authors: CRAIG R. G. , JOHNSON K.T.
Published: June 2007

Effects of materials and techniques on the accuracy of models used to make indirect restorations was measured using a 4‐unit posterior model containing a MOD and full crown preparation. Improved stone and fast setting epoxy dies backed with either improved stone or a thermoplastic hot melt stone were made from single‐viscosity addition silicone impressions. Technique variations included heating or not heating the impression, cooling and pouring dies and placement of the hot melt stone on set or unset epoxy. The dimensions of the MOD (L, W, H) and of the crown (W, H) dies were measured at 1 and 24 h. No clinically significant changes occurred between 1 and 24 h. The stone control reproduced the dimensions of the master die best, and models made by pouring epoxy into the impression followed by immediate pouring of the hot melt stone gave the poorest reproduction. Other variations in technique using epoxy for the anatomical portion gave no practical differences in accuracy. Of the epoxy dies, those prepared from a previously heated impression with hot melt poured after the epoxy set had the best values; however, epoxy dies were smaller than stone dies. The fast set epoxy was noteworthy for rapid processing and sharp detail, however, negative changes for W and H of the crown and H and L of the MOD showed that a die spacer would be essential in the preparation of indirect restorations.
Radiopacity of 12 visible‐light‐cured dental composite resins
Authors: TOYOOKA H. , TAIRA M. , WAKASA K. , YAMAKI M. , FUJITA M. , WADA T.
Published: June 2007

The radiopacity of 12 VL‐cured composite resins was determined with reference to an aluminum step‐wedge. Two anterior composites were radiolucent while two anterior and one anterior/posterior composites exhibited the radiopacity equal to, or slightly greater than, that of human enamel. Three posterior and one inlay composites possessed the radiopacity equivalent to, or in tiny excess of, that of human enamel. Three posterior composites had the radiopacity, fairly exceeding that of human enamel. Chemical analyses of the filler particles were carried out with SEM/EDX. It became evident that radiopaque fillers contained at least one radiopaque oxide component such as BaO, ZrO2 and Yb2O3 with varying concentrations. In general, the radiopacity of the composite resin was linearly proportional to the amount of the radiopaque oxide in the filler. It was suggested that ZrO2 was radiopacifier equivalent to, or even stronger than, BaO.
Periodontal cell migration into the apical pulp during the repair process after pulpectomy in immature teeth: an autoradiographic study
Authors: VOJINOVIĆ O. , VOJINOVIĆ J.
Published: June 2007

The migration of dental papilla cells into the periodontium during the process of root development may occur as part of the process involved in the formation of the periodontal tissues. The question posed is whether such cells under pathological conditions could retromigrate from periodontium into dental pulp and together with other apical pulp cells of immature teeth, take part in the production of additional dental tissue, e.g. 1) the tertiary/dentine under deep carious lesion where odontoblasts had been destroyed 2) the dentine bridge on an amputation wound and 3) calcfied tissue which closes an apex during the apexification process in immature teeth.

The migration of periodontal cells locally marked by H3 Thymidine immediately after partial pulpectomy in immature dog's teeth* was analysed at observation periods of 2, 24 and 50 h and also without H3 Thymidine labelling of periodontal cells 8 weeks after pulpectomy. The marked cells were found in the early observation periods after pulpectomy just in the places where the hard tissues were formed in the later observation period of 8 weeks. They were found in large numbers just around the coagulated necrotic foci. The finding supports the assumption that firm necrotic masses are a very important stimulative factor in the reparation process in pulp and periodontium. The experiment also corroborated the existence of periodontal cell retromigration into apical dental papilla of immature teeth. Future research should assess the possible role of the pathological condition in the determination of undifferentiated odontogenic ectomesenchymal periodontal cells into odontoblasts.
Front tooth replacement with Tübingen (Frialit®) implants
Authors: DE WIJS F.L.J.A. , VAN DONGEN R.C. , DE LANGE G.L. , DE PUTTER C.
Published: June 2007

127 Tübingen (Frialit®) implants have been clinically evaluated for a 10 year period. The implants were placed in the anterior region of the maxillae of 101 patients to replace lost incisors, cuspids and premolars. Seventy‐seven implants were placed within 3 months after loss of a natural anterior tooth, resulting in the preservation of the volume of the alveolar ridge and the contour of the surrounding soft tissues. This preservation of the volume of the alveolar ridge was due to the fact that the Tübingen implants have conical shapes and sizes, equal to those of the roots of natural teeth.

The dentine‐like colour and the biological properties of the bio‐inert Al2O3 implant‐material, in most of the cases was an advantage to the aesthetics of the prosthetic restorations and to the condition of the soft tissues in the permucosal area. The Tübingen implant is placed with a one‐phase technique implying special care for the temporary restorations to avoid premature loading. Also prevention of overloading the ceramic material by the fixed restoration needs special attention in the construction of posts, cores and crowns. The overall survival‐rate in this study with a mean follow‐up of 4–5 years was 87%. Patient and dentist satisfaction was high.
Effect of a fatigue test and chewing training on masticatory muscles
Authors: TZAKIS M.G. , KILIARIDIS S. , CARLSSON G.E.
Published: June 2007

The effects of fatigue induced by 30 min of intense chewing before and after 4 weeks of 1 h daily chewing training on masticatory muscles were studied in 15 healthy subjects while eight subjects served as controls. EMG measurements in the postural position and during maximal clenching in the intercuspal position and clinical examination of the stomatognathic system were performed. Marked clinical signs of dysfunction were recorded after the first fatigue test. The severity of dysfunction diminished during the 4‐week training period and was back at the baseline level at the end of it. In the second fatigue test, after the training period, the subjects developed less dysfunction. In the control group, a mainly stable pattern was found during the observation period. There was a great variation in EMG activity during the experimental period and there were no statistically significant changes observed between any of the recordings in any of the groups.
Periodontal status of teeth in contact with denture in removable partial denture wearers
Authors: YUSOF Z. , ISA Z.
Published: June 2007

The aims of the study were to determine the periodontal status of the teeth in contact with removable partial dentures (RPDs) and to compare them with other teeth in the opposing arch not related to any prothesis. The periodontal status was also assessed in relation to the age of the dentures. Four hundred and twenty‐seven patients treated with RPDs from 1981 to 1986 were recalled for examination. Prior to prosthetic treatment they were given periodontal treatment and fillings when required. Initially all were given oral hygiene instructions and motivation. They were reviewed regularly only on a short‐term basis. Eighteen patients were suitable for the present study comprising of eight males and 10 females whose mean age was 41 years. The RPDs were in use from 1.5 to 8 years (mean 4.6 years). The following parameters were assessed: Plaque index (PlI), Gingival index (GI), loss of attachment (LA) and tooth mobility. The wearing of RPDs resulted in higher PlI, GI and LA compared to the controls and these differences were statistically significant. There was an increased frequency of higher PlI, GI and LA with the increase in denture age. Minor changes in tooth mobility were observed. It was concluded that the wearing of RPDs was detrimental to periodontal health in patients whose oral hygiene was less than adequate.
The effects of electrogalvanic stimulation therapy on masticatory muscle dysfunction as determined by the pantronic reproducibility index
Authors: PAYNE J.A.
Published: June 2007

Patients with temporomandibular joint dysfunctional activity (TM dysfunction) present with a diverse spectrum of clinical signs and symptoms. The multifactorial aetiology of such disorders has been noted. Diagnostic and therapeutic problems arise due to the inadequacy of quantifying the dysfunction. TM dysfunction can affect the muscles of mastication which are responsible for mandibular movement. A pantographic reproducibility index (PRI) is available to quantitatively and qualitatively measure a subjects ability to reproduce mandibular border movements. Physical therapy modalities are used in the management of TM dysfunction. Electrogalvanic stimulation (EGS) is such an example. The effect of electrogalvanic stimulation on subjects with and without TM dysfunction was assessed by Pantronic PRI appraisal in 20 subjects. No statistically significant differences were noted. At the individual level, some changes were observed in susceptible subjects.
Transferring provisional restorations to final master casts
Authors: NEMCOVSKY C.E. , GROSS M.D.
Published: June 2007

Many principles guide preparation and fitting of provisional restorations. Their importance as a diagnostic tool is considered. Aesthetic, phonetic, functional, parafunctional and dysfunctional factors after evaluation in the provisional restorations have to be transferred to the master cast to incorporate them into the final restoration. A method for transferring morphology of provisional restorations to the master cast through preparation of a wax analogue fixed partial denture is presented. This method is precise, practical, suitable for most rehabilitation cases, and not clinically time‐consuming since most stages are carried out in the dental laboratory.
Jaw‐closing muscles: electromyographic activity of human subjects with reduced periodontal support
Authors: FERNANDES C.P. , PSARRAS V. , FREITAS L.B. , AHLGREN J.
Published: June 2007

The aim of this study was to compare the electromyographic (EMG) activity of jaw‐closing muscles of individuals with normal and reduced periodontal bone support. Fourteen adult subjects with more than 24 remaining teeth and low levels of periodontal inflammation, were selected for the study. Subjects of the control group had 90% of the periodontal bone support left, while other subjects presented a reduction of 52% of the original periodontal bone. Chewing experiments were performed using silicone tablets, carrots and white bread. The EMG of masseter and anterior temporal muscles was performed bilaterally, using bipolar surface electrodes, and the EMG amplitude was full wave rectified, integrated and the area extension under the curve was used to access muscle activity. The results of the chewing experiments did not show any statistically significant difference in the EMG activity of the study groups, irrespective of the chewing stuff. The height of periodontal bone support did not seem to influence the electroactivity of jaw‐closing muscles, indicating that reduced periodontal support might equally be able to withstand masticatory loads. Hence, individuals with reduced periodontal bone support revealed a similar EMG activity compared to subjects with normal periodontal bone support.
A computer‐controlled experimental set‐up enabling the quantification of motor performance in man, applied to mastication
Authors: OTTENHOFF F.A.M. , VAN DER BILT A. , VAN DER GLAS H.W. , BOSMAN F.
Published: June 2007

This paper describes a computer‐controlled experimental set‐up, which enables the simulation and manipulation of the resistance of food, the bolus size and reflex evoking events during chewing in man. Food resistance was simulated by an external downward directed force on the mandible during the closing phase. The force was supplied by a magnet‐coil system. A coil, rigidly attached to the subject's mandible, was located in a permanent magnetic field. By varying the current through the coil, the force on the coil and thus on the mandible could be adjusted. The current was on line computed as a function of the jaw gape. Food resistance and bolus size could be simulated and manipulated by varying the amplitude of the force and the jaw gape at which the force started, respectively. The possibility of varying these parameters could be used simultaneously and independently. Reflex evoking events were simulated by an additional loading or unloading force pulse, superimposed on the food‐simulating force. The set‐up has been tested during experiments in which food resistance, bolus size and reflex evoking events were simulated. Examples of these experiments are presented in this paper.
Effect of dentine on release of TEGDMA from resin composite in vitro
Authors: GERZINA T.M. , HUME W.R.
Published: June 2007

Triethylene glycol dimethacrylate (tegdma) is a component of some resin composites which contributes to their cytotoxicity. The presence of dentine between resin composite and test cells reduces the cytotoxicity in vitro. To determine why dentine has this protective effect, the diffusion of tegdma from a composite resin through dentine to the pulp space was compared with release directly into aqueous solution in vitro. Both release rate and total cumulative release of tegdma for the two groups, at times up to 100 days, were determined using reversed‐phase HPLC. Release rate directly into water was highest in the minutes immediately after immersion and declined thereafter. However, in the tooth model, using an equivalent mass and surface area of composite resin, no tegdma was detectable in the pulp space until 43min after restoration placement. The rate of diffusion through dentine from that time until day 1 was less than 1% of the highest (initial) direct release rate. The rate declined thereafter. It is relevant, however, that by day 3 the total cumulative release of tegdma through dentine was 60% of the direct release. Dentine therefore appears to exert its protective effect principally by retarding or ‘damping’ the initial high release of tegdma to a substantial degree.
Influence of dentine on the pulpward release of eugenol or acids from restorative materials
Authors: HUME W.R.
Published: June 2007

The diffusion gradient which develops across dentine and the clearance into the capillary circulation at the pulpal side of the tissue both reduce the concentration of potential toxins applied to dentine, thus protecting pulpal cells.

The data presented on eugenol indicates that when release of a potential toxin from a solid material is hydrolytic the limited wetness of dentine, i.e. the limited availability of water for hydrolysis, contributes to the protective effect of the tissue.

The data on strong acids indicates that a third protective mechanism, buffering by hydroxyapatite, can contribute to dentine's protective effect in situations where the potential toxin is strongly acid.

There may be other mechanisms by which dentine protects the pulp against chemical toxins from restorative materials. However, the three described: diffusion limitation; limited wetness for hydrolysis; and buffering by dentinal hydroxyapatite, appear to allow the relatively safe use of a wide range of tooth restorative materials.
Mercury vapour suppression by various liquid media
Authors: SUTOW E.J. , FOONG W.C. , RIZKALLA A.S. , JONES D.W. , POWER N.L.
Published: June 2007

Fresh and used photographic fixer, Merconvap® and water were evaluated for their ability to suppress the vapourization of mercury. Mercury vapour concentration above the four test storage liquids was measured at various times between 10 min and 335 days, using a mercury vapour measuring instrument. The data were analysed using a Student‐Newman‐Keuls multiple comparison test (P= 0.05). The results showed that fresh and used fixer and Merconvap® suppressed the vapourization of mercury to below the detection limit of the measuring instrument (0.01 mg/m3). Water was much less effective compared with the other liquids and showed an increase in mercury vapour concentration with log t.
Correlation between autoregressive moving‐average model parameters of electromyogram of human jaw closing muscles and maximum clenching time at intercuspal position
Authors: SHI C.‐S. , MAO Y. , GUO T.‐W.
Published: June 2007

During maximum clenching in the intercuspal position, surface electromyograms of left masseter and anterior temporal muscles were sampled in 16 healthy subjects with natural dentitions to establish a four‐order, autoregressive (AR) moving‐average (MA) model of the myoelectrical signals. The correlation coefficients and the linear regresssion between the model parameters and the clenching time were calculated. The model parameters had the positive or the negative correlation, and AR model parameters had the higher correlation than MA model parameters. The model parameters relate to muscular fatigue and the slope of the regressive equation relates to the endurance time of the isometric contraction.
Growth and/or acid production of Candida albicans on soft lining materials in vitro
Authors: NIKAWA H. , YAMAMOTO T. , HAYASHI S. , NIKAWA Y. , HAMADA T.
Published: June 2007

Effects of soft lining materials on the growth and/or acid production of Candida albicans were investigated using a simplified method monitoring the pH change in the growth medium. Reverse sigmoidal pH curves were observed with all samples and, as compared with acrylic, all soft lining materials inhibited fungal growth or acid production in the following way, i.e. delay of the beginning of a rapid and linear decline in pH, decreases in the rate of linear change in pH and increases in minimum pH.

Further examinations using a surface‐modified glass tube revealed that the order of Candida growth agreed with the relative hydrophobicity and adherence capacity of substrates, suggesting that this adherence capacity affected the yeast growth on their surfaces.

Besides adherence capacities of substrates, the powder, liquid and plasticizer of some soft lining materials directly inhibited Candida growth. Thus, the results obtained here revealed that several factors within soft lining materials affected Candida growth and/or acid production.
The effect of void space and polymerization time on transverse strength of acrylic‐glass fibre composite
Authors: VALLITTU P.K.
Published: June 2007

SUMMARY
The aim of this study was to establish (i) the causes and effects of void space formation in acrylic‐glass fibre composite material; and (ii) to clarify the effect of polymerization time of acrylic resin on the transverse strength of heat‐cured acrylic resin test specimens. In study I, three transverse sections of the continuous glass fibre reinforced test specimens (n= 48) were studied by a scanning electron microscope (SEM) and the SEM‐micrographs were analysed by a computerized picture analyser. The results suggested that the void space inside the test specimens is caused by a lack of the adsorbed monomer liquid in the fibre bundle before polymerization. The correlation coefficient between these two factors was –0.633 (P≥ 0.001). No correlation was found between the void space of the acrylic‐glass fibre composite and the transverse strength of the test specimens (r= 0.000, P= 1.000). The results of study 2 showed that the transverse strengths of test specimens (n= 240, total) subjected to polymerization of different time spans did not vary significantly (P < 0.05).
Radiographic signs in the TMJ and finger joints in elderly people
Authors: WOLF J. , KÖNÖNEN M. , MÄKILÄ E.
Published: June 2007

SUMMARY
Radiographic signs in the temporomandibular joints (TMJs) and finger joints were investigated in a series of 139 residents of elderly people's homes using panoramic tomographs and dorso‐volar radiographs. Radiographic signs in TMJs were found in 14% of the subjects, whereas all subjects had signs in at least one finger joint. The TMJs of men and women were equally affected, whereas signs in finger joints were more severe in women. No correlation was found between radiographic signs in TMJs and finger joints, suggesting that most signs in TMJs are probably due to local factors.
An in vitro investigation into the wear effects of selected restorative materials on enamel
Authors: JAGGER D.C. , HARRISON A.
Published: June 2007

SUMMARY
Abrasive wear testing of five restorative materials was carried otu with human enamel as the opposing surface using a wear machine specifically designed to simulate the masticatory cycle. The results showed that enamel demonstrated good abrasion resistance against amalgam and microfine composite and moderate abrasion resistance against gold. Conventional composite produced marked destruction of enamel and the greatest amount of enamel wear was produced by porcelain. The ranking order compared favourably with results from in vivo studies.
Relationship between craniomandibular dysfunction and oral parafunctions in Caucasian children with and without unpleasant life events
Authors: VANDERAS A.P.
Published: June 2007

SUMMARY
An epidemiological study was conducted to investigate the relationship between craniomandibular dysfunction and oral parafunctions in 386 children aged 6–10 years with and without unpleasant life events. The results showed statistically significant correlations between grinding, clenching, lip/cheek biting and muscle tenderness or pain, and clicking in subjects without unpleasant life events. Also, significant correlations were found in the same group between these parafunctions and difficulties in opening wide and pain on movements. When the definitional symptoms of craniomandibular dysfunction were aggregated, the chi‐square test revealed significant correlations between them and the same oral parafunctions. The correlations in subjects with unpleasant life events between grinding, clenching, lip/cheek biting and each sign and symptom of craniomandibular dysfunction were close to the significance level. No significant correlations were detected between the definitional symptoms and these parafunctions in this group. The present study suggests that in patients without unpleasant life events grinding, clenching, and lip/ cheek biting cannot be considered ‘necessary’ but can be ‘sufficient’ cause for the development of craniomandibular dysfunction. In subjects with unpleasant life events the origin of signs/symptoms of the dysfunction can be attributed to muscle tension or to another unknown aetiological factor.
Prognosis of overdenture abutments in elderly patients with controlled oral hygiene. A 5 year study
Authors: BUDTZ‐JÖRGENSEN. E
Published: June 2007

summary
The effect of controlled oral hygiene was studied in 31 elderly overdenture patients involving 72 abutments over a period of 5 years. Intensive instruction and motivation in oral hygiene care were carried out prior to prosthodontic treatment and two to four times yearly during the study period. The initial dental and periodontal conditions were very poor, with a mean loss of proximal bone adjacent to the abutments of 61%. During the study period, it was possible to maintain mean plaque index scores of 0.45−0.73 and mean gingival index scores of 0.89−0.95 adjacent to the abutments. There was no relationship between the patients' initial plaque index score and the oral and denture hygiene observed during the study. There was spontaneous regression of 4–5 mm periodontal pockets, whereas deeper pockets persisted. Seven abutments were extracted due to periodontal complications. Caries was a minor problem which could be controlled by hygienic measures, topical fluoride or fillings. The present study has shown that it was possible to maintain teeth as overdenture abutments to a large extent in elderly patients initially having a poor dental and periodontal status.
In vitro techniques for erosive lesion formation and examination in dental enamel
Authors: MILLWARD A. , SHAW L. , SMITH A.J.
Published: June 2007

summary
An in vitro experimental model has been developed for erosive lesion formation in dental enamel which can mimic in vivo conditions at the tooth surface. The features of this model provide a very reproducible method of producing erosive lesions in several teeth under identical conditions which can be varied to allow examination of a number of different parameters. A replica impression technique has also been developed for subsequent non‐destructive microscopic examination of the lesions and comparison with in vivo lesions.
Influence of the muscle tension on the masseteric silent period in children and adults
Authors: TAMURA Y. , BABA H. , YOSHIDA S.
Published: June 2007

summary
Three subject groups who have shown different biting forces were examined in order to investigate whether the physiological phenomenon that the duration of the silent period (SPD) of the masseter muscle would be influenced by background activities of the muscles. They were classified into child (CN, n= 10) and adult groups; the adult group was then further subdivided according to the strength of maximum biting force into a normal group (AN, n= 10) and a low biting force group with some symptoms (AS, n= 5). SPD was observed in maximum) and biting on a transducer (50N, 100N and maximum). With increase of muscle activities, SPD was significantly decreased in the AN and CN groups, whereas no significant changes were found in the AS group. When comparing SPDs among the three groups at the same voluntary effort, the AN group exhibited the shortest SPD followed by the CN and AS groups. The results suggest that SPD was positively influenced by the strength of the background activities of the muscles and that immaturity of the masseters in terms of muscle activity could affect the SPD.
Internal derangement and the accessory ligaments around the temporomandibular joint
Authors: OSBORN J.W.
Published: June 2007

summary
A model that describes the mechanics of jaw opening and the associated movements of the disc in a healthy human temporomandibular joint is used to explain the abnormal movements associated with internal derangement of the joint. A change in the constraints on jaw opening imposed by the accessory ligaments around the jaw joint can account for, among other things, clicks on opening and closing, disc displacement and replacement, and the conditions of open and closed lock.
Effects of occlusal splints on the asymmetry of masticatory muscle activity during maximal clenching
Authors: ABEKURA H. , KOTANI H. , TOKUYAMA H. , HAMADA T.
Published: June 2007

summary
The effects of stabilization splints on the electromyographic activity patterns of the masseter and anterior temporal muscles during maximal clenching in healthy subjects and subjects with different types of stomatognathic dysfunction syndrome were investigated. No marked effect of splints on the asymmetry of muscle activity during bilateral clenching was revealed immediately after splint insertion. During unilateral clenching in the intercuspal position (ICP), the relative asymmetry index (rAI) of the masseter muscles, detecting the imbalance of left and right muscular activity, was significantry increased. The use of splints suppressed the asymmetry of masseter muscle activity during unilateral clenching. This result suggests that the use of a splint is a method of suppressing clench‐caused aggravation of stomatognathic dysfunction in the presence of an imbalance between left and right muscle activities.
The fracture resistance of dental materials
Authors: UCTASLI S. , HARRINGTON E. , WILSON H.J.
Published: June 2007

summary
A novel test procedure was developed that provides the basis for a standard plain strain fracture toughness test to evaluate fracture resistance of resin‐based materials. This procedure utilizes a notched disc specimen. Using this technique, a new concept of‘Torque to initiate fracture (T)’was suggested. Also, fracture resistance can be assessed by means of critical stress intensity factor (K10). Using this method, the fracture resistance of direct restorative materials, resin‐based inlay/onlays and luting cements can be evaluated.
Sella‐Nasion linc revisited
Authors: SARHAN O. A.
Published: June 2007

summary
The anterior cranial base or the Sella‐Nasion (SN) line is often used by orthodontists as a reference line for assessment of dentofacial deformities. Its most important value is its relative stability, practicality and the ease of location of both points Sella and Nasion. Realiability of the SN line as a suitable asses‐ sor for exact facial measurements has been discussed before. The intent of this study was to identify unusual SN rotations for subjects acquiring normal and abnormal skeletal profiles and hence correct values associated with SN line, both in vertical and horizontal planes. A random sample of 150 British white school children aged 9‐12 years old was selected. Lateral head films of the children were traced and digitized. Point Nasion was joined to posterior nasal spine and also to point Sella, thus producing a z angle when the posterior nasal spine is extended to anterior nasal spine. Means and standard deviations were calculated. The mean angle S‐N‐PNS was 38°± 5 while the mean of angle N‐PNS‐ANS was 47°± 3. Comparison of those angles for patients of the same age group with the mean z angle can identify rotation of the palatal and Sella‐ Nasion planes. Hence corrections of angular measurements involving Sella point can be performed.
The sealing of the tooth/amalgam interface by corrosion products
Authors: BEN‐AMAR A. , CARDASH H.S. , JUDES H.
Published: June 2007

summary
A marginal gap exists between the amalgam restoration and the cavity walls. At this interface, there is a constant percolation of fluid containing ions, molecules and bacteria. With time, corrosion products of the amalgam components seal the gap at the amalgam/tooth interface. The corrosion processes for conventional and high copper amalgam and factors affecting the corrosion deposites are reviewed. Better amalgam adaptation to the cavity walls improves the chances of sealing the restoration by corrosion products. The effectiveness of cavity varnish in preventing microleakage until corrosive deposits are formed in discussed.
Effect of working side interferences on mandibular movement in bruxers and non‐bruxers
Authors: SHIAU Y.Y. , SYU J.Z.
Published: June 2007

summary
The effect of working interference on 13 bruxers and 14 non‐bruxers was studied by applying a metal overlay on the buccal cusps of the adjacent upper premolar and molar. The pattern and velocity of cyclic movement during gum chewing before and after overlay insertion were observed. EMG of the temporalis and masseter muscles was recorded bilaterally during the chewing movement. It was found that after insertion, one of the non‐bruxers complained of pain in the muscles, while such a complaint was not found in bruxers. Bruxing habit was reported to be less or eliminated in 44% of the bruxers, but no non‐bruxers became bruxers. The closing velocity was more often decreased immediately after overlay insertion, and the closing path near the occlusal phase was significantly narrower, with patterns of over‐extension and avoidance before reaching the occlusal phase. The delayed effects were a more vertically oriented chewing cycle without over‐extended closing movement, and an unretarded chewing velocity. It was concluded that within the experimental period a working side interference was tolerable in most of the subjects studied with or without a bruxing habit.
Biocorrosion study of titanium‐cobalt alloys
Authors: LIN J.H. CHERN , LO S.J. , JU C.P.
Published: June 2007

SUMMARY
The present work provides experimental results of corrosion behavious in Hank's physiological solution and some other properties of in‐house fabricated titanium‐cobalt alloys with cobalt ranging from 25–30% in weight. X‐ray diffraction (XRD) shows that, in water‐quenched (WQ) alloys, betatitanium is largely retained, whereas in furnace‐colled (FC) alloys, little beta‐titanium is found. Hardness of the alloys increases with increasing cobalt content, ranging from 455VHN for WQ Ti‐25 wt% Co to 525VHN for WQ Ti‐30 wt% Co. Differential thermal analysis (DTA) indicates that melting temperatures of the alloys are lower than that of pure titanium by about 600°C. Potentiodynamic polarization results show that all measured breakdown potentials in Hank's solution at 37°C are higher than 800mV. The breakdown potential for the FC Ti‐ 25 Wt% Co alloy is even as high as nearly 1200mV.
Determination of radiation energy emitted by light activation units
Authors: HARRINGTON E. , WILSON H.J.
Published: June 2007

SUMMARY
Since the introduction in the 1970s of single paste composite materials, there has been a rapid increase in the range of both materials and activation light units. This investigation is being undertaken as part of a larger study where the characteristics of both composite materials, light activation units and composite material/light activation unit cobinations, are being evaluated. This section of the stduy was undertaken to determine the characteristics of four light activation units. The equipment was developed to measure radiation energy over a wide range of illumination. This rage can be from the relatively low intensity of radiation transmitted throug restorative materials to the intensities of direct radiation from light activation units. The four light units tested had various radiation outputs between 225 000lx and 75 000lx. All the units, apart form one, showed a decrease in light output with successive applications. The units emitted radiation outside the optimum range of 440–500 nm, which may produce damaging radiation and glare. Although the extreme intensities varied threefold the effect on depth of cure of one material varied by only 16%.
The temporal/masseter co‐contraction: an electromyographic and clinical evaluation of short‐term stabilization splint therapy in myogenous CMD patients
Authors: VISSER A. , NAEIJE M. , HANSSON T.L.
Published: June 2007

SUMMARY
The short‐term effect (3–6 weeks) of the use of a stabilization splint was investigated in a group of 35 myogenous craniomandibular disorder patients. The patients were clinically examined and surface EMG recordings of the temporal and masseter muscles were made during clenching in the intercuspal position (ICP), immediately after the insertion of the splint (SSP), and after at least 3 weeks of splint treatment (SSP 3). With the use of the error variance of the activity index changes in EMG activity were investigated. Three groups of patients were then recognized. One group showed a decrease in temporal muscle activity during splint treatment. Another group did not show any significant change during splint treatment. The third group showed an increase of temporal muscle activity. In general, significant reductions in the amount of static pain were found. In the group with a significant reduction of temporal muscle activity (n=15) there was a greater decrease in the amount of static pain (P≤0.05) than in the group (n=4) with a significant increase of temporal muscle activity. The results may indicate that the temporal muscle plays an important role in the perception of static pain in the masticatory system.
Temporomandibular joint mobility assessment: a comparison between four methods
Authors: DIJKSTRA P.U. , DE BONT L.G.M. , STEGENGA B. , BOERING G.
Published: June 2007

SUMMARY
Temporomandibular joint (TMJ) mobility is assessed in different ways. Measurement of the interincisal distance in maximal mouth opening added to the vertical overlap of the dentition, i.e. linear mouth opening (LMO); measurement of angular displacement of the mandible relative to the cranium at maximal mouth opening, i.e. angle of mouth opening (AMO); assessment of the condylar position relative to the articular eminence performed on transpharyngeal radiographs in maximal mouth opening, i.e. condylar mobility (CM); measurement of angular displacement of the mandible at maximal mouth opening relative to the closed mouth position of the mandible, assessed on transpharyngeal radiographs in maximally opened and in closed mouth position, i.e. radiographic angle of mouth opening (RAMO). To compare these TMJ mobility assessment methods and to analyse the relationship between LMO, AMO and mandibular length (ML), 28 healthy volunteers (13 females, 15 males), mean age 29.6 years (range 21–41) with a symmetrical mouth opening pattern were assessed. LMO, AMO, ML, and RAMO were measured and CM was assessed on transpharyngcal radiographs. LMO and AMO were strongly and significantly related (r=0.71). LMO was significantly influenced by AMO and ML. No significant differences between AMO and RAMO were found. CM was strongly and significantly related to AMO (r=0.72) and weakly but significantly related to LMO (r=0.42). Based on the results of this study recommendations are made regarding the appropriate application of TMJ mobility assessment methods.
Modelling the effects of enamel anisotrophy with the finite element method
Authors: REES J. S. , JACOBSEN P. H.
Published: June 2007

SUMMARY
The finite element method was used to model an in vitro tooth loading system. The dentine was modelled as a linear elastic and isotropic material, while the enamel was modelled as an anisotropic material to take account of the biological variation in prism angulation. The elastic modulus values of enamel and dentine used in this analysis were altered in order to replicate the movement of the in vitro system. It was found that a dentine modulus of 15 GPa and an enamel modulus of 80 GPa in the principal prism direction gave the best replication of cuspal movement.
Odds ratio in the estimation of the significance of occlusal factors in craniomandibular disorders
Authors: KIRVESKARI P. , ALANEN P.
Published: June 2007

summary
The usage of odds ratios for estimating the significance of occlusion is based on the assumption that the aetiological factors are additive and interchangeable in several different composite causes. If the factor studied is a necessary causal factor, odds ratios cannot be used in risk estimation. The present study analysed odds ratios in a sample of children half of whom had undergone an annual prophylactic elimination of occlusal interferences. The sample consisted of 178 children followed up for 5 years from the baseline age of 5 or 10. The distribution of interferences was computed for children with tenderness of the masticatory muscles (‘cases’), and for children without (‘controls’). Although the increase in the number of children free from interferences was not remarkable, the overall result was statistically significant (P 0.01). None of the children free from interferences showed muscular tenderness at any of the annual examinations. Therefore, odds ratios could not be calculated in our study sample. It is concluded that estimation by means of odds ratios of the significance of occlusal factors in CMD may be misleading.
Surface and colloid chemical aspects of saliva particle interactions
Authors: GLANTZ P.‐O. , FRIBERG S. E. , CHRISTERSSON C. E. , BAIER R. E.
Published: June 2007

summary
Sections of flash‐frozen saliva particle mixture were examined by transmission electron microscopy. The saliva samples used consisted of 40% by volume parotid and 60% by volume submandibular sublingual fractions. One mL of the saliva was mixed with 0.1 mL of either hydrophilic or hydrophobic particles of 0.9 μm diameter. The micrographs of the saliva and hydrophilic particles mixes showed the multiple spherical particles in the salivary network structures. Micrographs of the saliva and hydrophilic particle mixes showed the presence of few such objects; when observed, the particles were located only in the electron dense part of the salivary structures.
Functional evaluation after TMJ surgery
Authors: WIDMARK G. , HARALDSON T. , KAHNBERG K.‐E.
Published: June 2007

summary
Oral function was evaluated in 30 patients (25 women and five men) after TMJ surgery by means of bite force measurements. Twenty‐seven discectomies and three condylectomies had been performed. The follow‐up period was, on average, 2.5 years. The mean bite force values on the function level ‘biting as when chewing’ was for the whole group 125.3 N on the right side and 128.8 N on the left side. The maximal bite force was on average 362.5 N and maximal endurance time on average 32 s. All test results showed big ranges. No significant differences between right and left side or operated and non‐operated side could be found on the tested function level ‘biting as when chewing’. The found bite force values were high in comparison with another similar study. The results were also compared with another group of patients (n= 6) who were examined before and 6 months after surgery. As far as bite force reflects oral function the results are indeed very encouraging.
Implant prosthodontic treatment options for the edentulous patient
Authors: ZARB G.A. , SCHMITT A.
Published: June 2007

summary
Longitudinally documented benefits for edentulous patients of treatment outcomes of the osseointegration technique demonstrate compelling therapeutic results. Heterogeneous population groups, treated in different centres by various dental specialists, have provided impressive evidence of a minimal burden of illness associated with the procedure. A critical appraisal of the many

components of any implemented treatment paradigm demands repeated analysis of the factors which enable patients' informed consent and dentists' optimal decision making. This paper reviews those salient aspects which impact upon decision making with implant‐supported prostheses. It emphasizes the predominance of bone structure in selecting the most likely favourable treatment outcome.
Comparison of partial and full crowns as retainers in the same bridge
Authors: NEVALAINEN M. , RUOKOLAINEN T. , RANTANEN T. , MÄKILÄ E. , KÖNÖNEN M.
Published: June 2007

summary
The purpose of this study was to assess longitudinally the success of partial and full crown abutment pairs in the same bridges. Fifty patients with a mean age of 45 years (range 22–70 years) were examined during spring 1981 (1–5 year follow‐up), 33 of whom were examined a second time during spring 1990 (10–15 year follow‐up). The status of the partial crowns, full crowns, and their abutment teeth was assessed using standardized questions, and clinical and radiographic examinations. At the first follow‐up examination, all partial and full crowns, and consequently all bridges, were still in use. Before the second follow‐up examination one of the full crown abutments had become badly decayed, and the bridge, including the partial crown, had been removed. The failure rate was 0.2% per year for the full crown as a unit, and consequently 0.2% per year for the bridge as a unit.