Oral function and vertical jump height among healthy older people in Japan

OBJECTIVE

Vertical jump height and oral function affect the general muscle condition. This study aimed to evaluate the association between vertical jump height and oral function among healthy older individuals.

BASIC RESEARCH DESIGN

Cross-sectional analytic study.

PARTICIPANTS

231 independent older people (mean age, 74.4 ± 5.6 years) who participated in the Kyoto Elders Physical Fitness Measurement Research Project. Individuals with partial or complete edentulousness who did not use a prosthetic device or complained of oral/maxillofacial pain were excluded from the study.

INTERVENTIONS

Grip strength was measured using a Smedley Hand Dynamometer. To measure masticatory performance, the participants were instructed to chew a gummy jelly on their habitual chewing side (left or right) for 20 s. Occlusal force, contact area, and pressure were also assessed.

MAIN OUTCOME MEASURES

The outcome variable was vertical jump height. The predictor variables were physical status (age, body mass index, and grip strength), oral status (number of present teeth and denture use), and oral function (masticatory performance, occlusal force, occlusal contact area, occlusal pressure, and tongue pressure). These relationships were evaluated with univariate analysis, and then multiple regression analysis was performed with age as the covariate for each male and female participant.

RESULTS

Vertical jump height was significantly associated with grip strength in both men and women. Moreover, in women, it was associated with masticatory performance, occlusal force, and occlusal contact area.

CONCLUSIONS

Vertical jump height was closely associated with oral function among healthy older women.

Manometric evaluation of oral function with a hand-held balloon probe

Tongue pressure measured with a disposable hand-held balloon probe has been used for assessing tongue function; however, no diagnostic standard for assessing other oral functions exists currently. In this study, to develop a method for multifactorial manometric evaluation of oral functions, 20 men and 20 women (21-32 years of age) were instructed to apply 7-s maximal voluntary muscular effort on a hand-held balloon probe placed against the anterior and lateral parts of the palate, buccal surface of the molars on the habitual chewing side and labial surface of the anterior teeth for measuring anterior and posterior tongue, cheek and lip pressures (LPs), respectively. Intra-session reproducibility was determined by three repeated measurements, and associations between the obtained and the conventional data on oral diadochokinesis were tested. The men exhibited higher values of all the pressure types. Further, both genders showed a positive correlation between anterior and posterior tongue pressures (PTPs) (P < 0·05), but only the women exhibited positive correlations between anterior tongue and cheek pressures, cheek and PTPs, anterior tongue and LPs, and cheek and LPs (P < 0·05). No statistically significant correlation was found between the pressures and the number of syllabic articulations, except between LP and the number of /pa/ articulations in the women (r = 0·524, P < 0·05). In conclusion, the balloon probe method enables objective manometric evaluation of oral functions and could be an effective tool for clinical epidemiological studies and evidence-based decision-making in nursing care.

Dynamic viscoelastic properties of vinyl polysiloxane denture soft lining materials

The aim of this study was to investigate the dynamic viscoelastic properties of seven commercially available vinyl polysiloxane denture soft lining materials. Five rectangular specimens (2 x 10 x 30 mm) were prepared from each material. The complex modulus E* (MPa) and loss tangent (tan delta) of each specimen were determined with a non-resonance forced vibration method using an automatic dynamic viscoelastometer at 1 Hz after 1 day of dry storage, and after 1, 30, 60, 90 and 180 days of wet storage at 37 degrees C. All data were analysed using one-way anova and Bonferroni/Dunn's test for multiple comparisons with a significance level of P < 0.01. All materials varied widely in terms of viscoelasticities and showed both an increase in E* and a decrease in tan delta at 1 Hz after the 1-day wet storage. After 60 days of wet storage, both E* and tan delta did not change significantly. The stiffer materials (>30% filler content) with high E* values (>2.00 MPa) showed elastic behaviour with tan delta values of around 0.03. The softer materials (6% filler content) with high tan delta values (initial value > 0.10) showed viscous behaviour and were easily affected by water absorption after the 1-day wet storage. It can be concluded that for the proper selection of vinyl polysiloxane denture soft lining materials, it is very important to evaluate the viscoelastic properties after 60 days of wet storage.

Handy measurement for tongue motion and coordination with laryngeal elevation at swallowing

At the oral stage of swallowing, the tongue plays a major role and proper tongue performance is necessary to form the bolus and transfer it to the pharynx. For the present study we built a prototype device for safe and handy objective estimation of tongue motion and coordination with laryngeal elevation at swallowing. The device records tongue pressure by means of two strain gauge pressure transducers aligned 20 mm apart on a brass strap placed along the palatal midline. Laryngeal vibration is recorded with piezo-electric acceleration transducers. Time differences between pressure onset at the anterior and posterior transducers and the first spike from laryngeal vibration are measured. Ten healthy subjects were asked five times to swallow 5 mL of water. Pressure onset at the anterior transducer preceded posterior pressure by 294 +/- 164 ms. Given the distance between the transducers, the tongue contracted (squeezed) at a speed of 93 +/- 60 mm s(-1). Laryngeal vibration occurred 671 +/- 175 ms after the onset of anterior pressure. There was considerable variation in these parameters between subjects. Though the data is limited, the device successfully and easily revealed certain aspects of tongue motion and coordination with laryngeal elevation.

Masticatory ability in 80-year-old subjects and its relation to intake of energy, nutrients and food items

OBJECTIVE

The aim of the present study was to analyse the relationship between masticatory ability (self-assessed masticatory ability and bite force) and intake of energy, nutrients and food items in a population sample of elderly subjects.

DESIGN AND SUBJECTS

From a population sample of 80-year-old people, 160 individuals (74 men and 86 women) took part in an odontological study.

MAIN OUTCOME MEASURES

A dental examination including bite force recording, a questionnaire focusing on self-assessed masticatory ability, and a dietary interview.

SETTING

Department of Geriatric Medicine, Göteborg University, Sweden.

RESULTS

The dental status among the participants varied much (from edentulous in both jaws--22%--to more than 20 natural teeth--30%). The mean maximum bite force was higher in men (165 N) than in women (105 N). Bite force was significantly correlated to the Eichner index and to the number of teeth. One third of the subjects reported no masticatory problem, whereas 18% identified > or = 3 such problems. The intake of energy and nutrients varied much but the means were well above recommended values. The correlations between dental status and bite force on one side and dietary intake on the other side were in general weak and most often statistically non-significant. Impaired general health and reduced dentition were both associated with more masticatory problems.

CONCLUSION

The examined sample of 80-year-old subjects had a great variation in dental status, bite force and self-assessed masticatory ability, but these factors had only a minor influence on dietary selection and intake, which on average were well above recommended values.

Chloride conductance determining membrane potential of rabbit articular chondrocytes

Membrane conductance of cultured rabbit articular chondrocytes was characterized by means of the patch-clamp technique. The resting membrane potential of the articular chondrocytes was about -42 mV. The membrane potential shifted in accordance with the prediction by the Nernst equation for Cl- when intracellular and extracellular concentrations of Cl- were changed. On the other hand, change in extracellular concentration of K+ produced no shift in the membrane potential of chondrocytes. The Cl- channel blocker 4-acetamido-4'-isothiocyanatostilbene-2'2-disulfonic acid (SITS) depolarized the membrane potential. These findings suggest that the membrane potential of the chondrocytes is determined mainly by Cl- conductance. Using the cell-attached patch-clamp method, a large unitary conductance of 217 pS was observed in the articular chondrocytes. The unitary current was reversibly blocked by SITS. Therefore, the unitary current was carried by Cl-. The Cl- channel showed voltage-dependent activation and the channels exhibited long-lasting openings. Therefore, the membrane potential of rabbit cultured articular chondrocytes was mainly determined by the activities of the large-conductance and voltage-dependent Cl- channels.

The effects of buccolingual width and position of occlusal rest seats on load transmission to the abutments for tooth-supported removable partial dentures

PURPOSE

The suitable buccolingual width and the location of occlusal rest seats for removable partial dentures have not been scientifically established. The aim of the present study was to use three-dimensional geometric analysis to evaluate the effects of buccolingual width and the location of occlusal rest seats on load transmission to the abutments for tooth-supported removable partial dentures.

MATERIALS AND METHODS

A tooth-supported portion of a maxillary removable partial denture with two conventional circumferential cast clasps and an indirect retainer was analyzed. Occlusal loading of 100 N was applied to the buccal mesial cuspal incline 2.0 mm from the central fossa of the first molar or to the lingual mesial cuspal tip. Four combinations of position and width (wide, buccal shift, middle, and lingual shift) were simulated.

RESULTS

For buccal loading, the wide rests and buccal-shift rests produced lower tensile forces at the indirect retainer. For lingual loading, the buccal-shift rests produced the lowest compressive force to the anterior abutment.

CONCLUSION

Based on the tooth-supported removable partial dentures that were analyzed, buccal shifting of the rest seats seems to be advantageous for load transmission to the abutments.

Analysis of stiffness and stress in I-bar clasps

An I-bar clasp is one of the most popular direct retainers for distal-extension removable partial dentures. However, no adequate information is available on the shape associated with biomechanics. This study aimed (1) to establish a three-dimensional (3D) finite-element modelling method of I-bar clasps, and (2) to clarify the effect of the shape on the stress and stiffness of I-bar clasps. 3D computer models of I-bar clasps were created with vertical and horizontal straight sections connected with a curved section with six parameters: thickness of the clasp tip (T), width of the clasp tip (W), radius of the curvature (R), horizontal distance between the base and the vertical axis (H), vertical dimension between the tip and the horizontal axis (V), taper (change of width per unit length along the axis)(Tp). Stress decreased as T, W, R and Tp increased, and as V decreased. Stiffness (which is proportional to retention) increased as T, W, R and Tp increased, and as H and V decreased. In both stress and stiffness, the effects of T and Tp were especially large. From the results, a systematic formula between the clasp shape and the stiffness was derived.

Finite element analysis on preferable I-bar clasp shape

An I-bar clasp is one of the most popular direct retainers for distal-extension removable partial dentures. However, no adequate information is available on preferable shape as determined by biomechanics. This study aimed (1) to investigate, by finite element analysis (FEA), the dimensions and stress of I-bar clasps having the same stiffness, and (2) to estimate a mechanically preferable clasp design. Three-dimensional FEA models of I-bar clasps were created with vertical and horizontal straight sections connected by a curved section characterized by six parameters: thickness of the clasp tip, width of the clasp tip, radius of the curvature, horizontal distance between the base and the vertical axis, vertical dimension between the tip and the horizontal axis, and taper (change of width per unit length along the axis). Stress was calculated with a concentrated load of 5 N applied 2 mm from the tip of the clasp in the buccal direction. A thinner and wider clasp having an taper of 0.020-0.023 and radius of curvature of 2.75-3.00 showed less stress. The results suggest that such a shape might be the preferable I-bar clasp shape as biomechanical viewpoint.

Effect of abutment tooth reinforcement techniques on the fracture resistance of removable partial denture master casts

PURPOSE

The purpose of this study was to compare the mean loads required to fracture an isolated stone abutment tooth when various reinforcement techniques were used: (A) no reinforcement, (B) surface hardening, (C) impression trimming, (D) dowel placement, and (E) impression trimming plus dowel placement.

MATERIALS AND METHODS

Die stone premolar specimens for each group (n = 4) were loaded perpendicular to the tooth long axis in 100-g increments 25 hours after pouring the impression. Mean load to failure was determined for each group. Data were evaluated with a one-way analysis of variance (alpha = 0.05) to determine differences among groups. Paired comparisons of factor level means were made with Tukey's q-test.

RESULTS

The mean fracture load for Group E (7.6 kg) was significantly greater than Groups A (2.0 kg), B (2.1 kg), and C (3.4 kg). No significant difference was found between Groups D (6.0 kg) and E.

CONCLUSIONS

Dowel reinforcement with impression trimming at the cervical portion of the abutment tooth resulted in significantly greater fracture resistance than the control, surface model hardener, or impression trimming alone. J Prosthodont 2001;10:22-25.

Dimensional measurement and finite element analysis of I-bar clasps in clinical use

An I-bar clasp is a popular retainer for distal-extension removable partial dentures. However, there have been almost no evidence-based criteria on the mechanically preferable shape. The present study aimed to investigate the variations of dimension in I-bar clasps used in patients, and to clarify the effect of the variations on stiffness and stress of I-bar clasps by finite element analysis. Dimensions (thickness, width, taper, radius of curvature, length, relation to oral structures) of 23 I-bar clasps were measured. A three-dimensional finite element model was made for each measured I-bar clasp with vertical and horizontal straight sections connected with a curved section. A concentrated load of 5 N was applied at the lowest point of the tip that contacted the abutment in the buccal direction. Maximal equivalent stress and stiffness of each clasp were evaluated. The measured dimension, stiffness, and maximum stress showed wide variations. Mean stiffness was far from the proper one, and mean stress was near the proportional limit of Co-Cr alloy. Considering the stiffness and stresses in this study, only six clasps out of 23 were appropriate. These results suggest that evidence-based criteria of preferable shape of I-bar clasps should be determined.

A method for quantifying overall satisfaction of complete denture patients

Reproducible and quantitative evaluation of patient satisfaction with their complete dentures is of great importance for preoperative diagnosis, treatment planning and assessment of complete denture treatment outcome. This study attempted (1) to clarify the degree of contribution of various factors to overall satisfaction, and (2) to develop a method for quantitative assessment of overall satisfaction with complete dentures. Twelve satisfaction factors and a three-grade scale were used to assess 302 complete denture patients. The contribution of each grade of the 12 factors to the overall satisfaction level was determined by multiple regression analysis. Seven factors were highly correlated to the overall satisfaction. Based on the level of contribution by these seven significant factors, a scoring method for satisfaction was established. Category scores for these factors were calculated and the sum of the category scores was converted to an integer between 0 and 100. The resulting quantification score was closely correlated with overall satisfaction. A protocol for scoring overall satisfaction was developed based on the scientifically analysed contribution of each satisfaction factor.

Biomechanical effects of double or wide implants for single molar replacement in the posterior mandibular region

Double implants have been thought to have biomechanical advantages for single molar replacement. To evaluate the effectiveness of double implants versus a wide implant, the vertical forces and torque on each implant were calculated by three-dimensional geometric analysis. Buccal load (100N) perpendicular to cuspal inclination (20 degrees) was applied at the occlusal surface of the superstructure. The three kinds of load points (A, B, C) were 1.5, 3.5, and 5.5 mm from the mesial contact point, respectively. Three implants were compared: mesial and distal double implants (phi 3.3 mm), and a wide implant (phi 5 mm). The wide implant showed torque around the long axis (1.8-15.0 N x cm) whereas double implants had no torque. On the other hand, the vertical forces on the mesial double implant were both smaller (60%: loaded at point C) and larger (140%: loaded at point A) than the wide implant. Given the smaller surface area of the mesial double implant, this large force may generate much higher stress in the peri-implant bone. These results suggest that the biomechanical advantage of double implants for single molar replacement is questionable when the occlusal force is loaded at the occlusal surface near the contact point.

Finite element analysis of stress relaxation in soft denture liner

To gather knowledge related to establishing criteria for selecting soft denture liners for individual patients, the effects of certain properties of soft denture liners on stress distribution were evaluated by two-dimensional finite element analysis. A partial mandibular edentulous ridge crest was modelled. Six combinations of thickness (mucosa: 1 or 2 mm; soft denture liner: 1, 2, or 3 mm) and 18 combinations of Young's modulus (mucosa: three kinds; soft denture liner: six kinds) were analysed. The ratio of maximum to minimum stress in the mucosa (stress ratio) was calculated to estimate stress concentration. In the case of thin mucosa (1 mm thickness), the lower the Young's modulus of the soft denture liner, the lower the stress ratio. However, if the soft denture liner had a lower Young's modulus than the mucosa, stress concentrated adversely. These results suggest that the elasticity of the soft denture liner should match the elasticity of the mucosa to obtain the optimum cushioning effect.

Creating a vertical stop for interocclusal records

This article describes a method of making an accurate interocclusal record when the most distal tooth is an abutment of a fixed partial denture. The method uses conical stops, prepared in the enamel of the abutment or made of composite or a metal core covered with composite, to maintain the vertical dimension of occlusion and to act as a third point of reference for a stable occlusal relationship when occluding the definitive casts. This article also explains how to use the cones and how to make each variety.

Immediate maxillary denture base extension for posterior palatal seal

A procedure for extension of the maxillary denture base for development of a posterior palatal seal is described. The technique involves provisional extension with paraffin wax and adding direct relining resin supported by a silicone putty core. This simple, quick procedure achieves immediate recovery of retention for underextended maxillary dentures without additional laboratory procedures.

Evaluation of lower oesophageal sphincter pressure using endoscopic manometric sleeve assembly

BACKGROUND

The purpose of this study was to establish a method to determine lower oesophageal sphincter (LOS) pressure using an endoscopic manometric sleeve assembly.

METHODS

We used a 250-cm, three-lumen, 2.2-mm external diameter silicon catheter with a 3-cm sleeve sensor that was passed easily through the biopsy channel (2.8 mm diameter) of the gastroscope. Each lumen was perfused with distilled water using a low-compliance, pneumohydraulic capillary infusion system. Forty-seven healthy subjects and 35 patients with oesophageal disorders underwent study during routine diagnostic endoscopy. In 27 of the subjects, standard transnasal manometry with a three-lumen, 4.5-mm diameter polyvinyl catheter with a 5-cm sleeve sensor was also performed.

RESULTS

Lower oesophageal sphincter pressure (LOS) was evaluated in all subjects (median pressure 16 mmHg, range 0-55 mmHg) for 6 min during routine endoscopic examination. The LOS pressure readings between standard and endoscopic manometry correlated well. The LOS pressure was significantly lower in healthy subjects with hiatal hernia than in those without hernia and was also significantly lower in patients with reflux oesophagitis than in healthy subjects.

CONCLUSIONS

Endoscopic manometric sleeve assembly was used during routine endoscopic examination and was useful for easily determining LOS pressure. It could be used for evaluation of oesophageal motility disorders, thus avoiding the use of a more invasive and time-consuming method.

A biomechanical effect of wide implant placement and offset placement of three implants in the posterior partially edentulous region

To prevent loosening or fracture of screws retaining the prosthesis to the implants in the posterior partially edentulous region, the use of staggered buccal and lingual offset placement or wide implants is suggested. However, it is not known how this usage compensates for the torque produced by lateral occlusal forces. This study evaluated the effectiveness of offset placement of three implants and a wide implant placement at the most posterior site. Three-dimensional geometric analysis was used to calculate the tensile force applied to gold screws in clinical situations with buccal or lingual loading perpendicular to cuspal inclination (10 or 20 degrees ). Four variations of the placement of three implants (3.75 mm) are: (1) straight; (2) buccal offset of the second implant; (3) lingual offset of the second implant; (4) a wide implant (5 mm) placement at most posterior site. The offset placement did not always decrease tensile force at the gold screw, but wide implant placement and decrease in cuspal inclination did.

Accurate procedure for transferring a cast replacement clasp arm to a removable partial denture

This article describes a simple, quick and accurate procedure to replace a broken bar-type clasp with a new clasp arm. This procedure involves a resin matrix that transfers a new clasp arm from a working cast to a removable partial denture. This simple procedure enables quick and precise replacement of a broken clasp arm.

Dynamic viscoelastic properties of antimicrobial tissue conditioners containing silver-zeolite

OBJECTIVES

The purpose of this study was to determine the effects of including the antimicrobial silver-zeolite (SZ) on the dynamic viscoelastic properties of various tissue conditioners.

METHODS

The dynamic viscoelastic properties of five commercially available tissue conditioners: Visco-gel (VG), GC Soft-Liner (SL), FITT (FT), SR-Ivoseal (IV) and Shofu Tissue Conditioner (TC) containing SZ were evaluated after 1 and 28 days of water- and artificial saliva immersions with the use of complex modulus and loss tangent parameters. Values for these two parameters for each tissue conditioner were statistically analyzed by one- and two-way ANOVA and Bonferroni's test.

RESULTS

Complex modulus and loss tangent values of TC were not significantly different among specimens containing 0, 2, 5 and 10 wt.%-SZ, respectively. In FT and TC containing 2 wt.%-SZ, these values were not significantly different between 1 and 28 days in both water- and saliva immersions.

CONCLUSION

The results suggest that incorporating SZ does not affect TC's inherent dynamic viscoelastic properties, while the other tissue conditioners investigated may be found to have changed viscoelastic properties as a consequence of the inclusion of SZ.

The effectiveness of a new algorithm on a three-dimensional finite element model construction of bone trabeculae in implant biomechanics

More validity of finite element analysis (FEA) in implant biomechanics requires element downsizing. However, excess downsizing needs computer memory and calculation time. To evaluate the effectiveness of a new algorithm established for more valid FEA model construction without downsizing, three-dimensional FEA bone trabeculae models with different element sizes (300, 150 and 75 micron) were constructed. Four algorithms of stepwise (1 to 4 ranks) assignment of Young's modulus accorded with bone volume in the individual cubic element was used and then stress distribution against vertical loading was analysed. The model with 300 micron element size, with 4 ranks of Young's moduli accorded with bone volume in each element presented similar stress distribution to the model with the 75 micron element size. These results show that the new algorithm was effective, and the use of the 300 micron element for bone trabeculae representation was proposed, without critical changes in stress values and for possible savings on computer memory and calculation time in the laboratory.

Finite element analysis of the effect of vertical curvature on half-oval cast clasps

High stresses in half-oval cast clasps are the main causes of deformation or fracture. A vertical curvature in clasps is said to be effective in reducing stress. However, such claims lack scientific basis. The purpose of the present study was to evaluate stress and stiffness in a three-dimensional (3D) finite element analysis (FEA) model of clasps with different vertical curvatures, cross-sectional forms and tapers, and to clarify the effect of vertical curvature on the half-oval cast clasp. Circumferential clasp arms for the mandibular second premolar were analysed by 3D FEA. The clasp arms were approximated by curved cantilever beams with a half-oval cross-section around a cylinder. The radius of curvature was set at 4 mm and the angle subtended by the clasp arm was 120 degrees. The clasp tip was set at a point 2 mm lower than the base. In the 'No-taper' half-oval clasp arm, stress increased and stiffness decreased with the increase in vertical curvature. In the shape of a preformed wax pattern (thickness/width = 0.80, tip/base = 0.70), stress and stiffness decreased slightly. In an 'Original' form (thickness/width = 0.33, tip/base = 0.80), vertical curvature had a very slight effect on stress and stiffness, and stress was the lowest. These findings suggest the superiority of the 'Original' form, with less stress and no effect of vertical curvature.

The effectiveness of element downsizing on a three-dimensional finite element model of bone trabeculae in implant biomechanics

More validity of finite element analysis in implant biomechanics requires element downsizing. However, excess downsizing needs computer memory and calculation time. To investigate the effectiveness of element downsizing on the construction of a three-dimensional finite element bone trabeculae model, with different element sizes (600, 300, 150 and 75 microm) models were constructed and stress induced by vertical 10 N loading was analysed. The difference in von Mises stress values between the models with 600 and 300 microm element sizes was larger than that between 300 and 150 microm. On the other hand, no clear difference of stress values was detected among the models with 300, 150 and 75 microm element sizes. Downsizing of elements from 600 to 300 microm is suggested to be effective in the construction of a three-dimensional finite element bone trabeculae model for possible saving of computer memory and calculation time in the laboratory.

Evaluation of the colorectal wall in normal subjects and patients with ulcerative colitis using an ultrasonic catheter probe

BACKGROUND

Ulcerative colitis is usually evaluated by barium enema and colonoscopy, methods of imaging that are limited to the mucosal surface. Endoscopic ultrasonography (EUS) is the best modality for the evaluation of transmural changes in the bowel wall. We therefore evaluated the colorectal wall in normal control subjects and patients with ulcerative colitis using an ultrasonic catheter probe.

METHODS

Endoscopic ultrasound with a catheter probe was performed on 36 normal control subjects (36 examinations) and 72 patients (111 examinations) with documented ulcerative colitis.

RESULTS

In normal control subjects, the total wall, mucosa, submucosa, and muscularis propria were significantly thicker in the rectum than in the colon. There was no significant difference in the thickness of the colon and rectum among different age groups or between men and women. In ulcerative colitis, we classified the boundary of each layer into three patterns (smooth, irregular, and blurred) and then classified the wall into six types. In Matts grade 2 and 3 ulcerative colitis lesions, the total wall and each layer were significantly thicker than lower grade lesions and normal control subjects. For grade 1 and most of the grade 2 lesions, the boundary of each layer was smooth. In some of the grade 3 lesions, the mucosa-submucosa and submucosa-muscularis propria layer borders were abnormal. In all grade 4 cases, the mucosa-submucosa boundary was blurred. There was some correlation between the Matts grade and EUS findings except for Matts grade 3 lesions which had various EUS patterns.

CONCLUSION

Endoscopic ultrasound with a catheter probe is a useful modality for the transmural assessment of the colorectal wall and, when used in conjunction with the many clinical and endoscopic parameters currently available, may contribute to the diagnosis and treatment of ulcerative colitis.

Post-impression preparation to prevent fracture to isolated abutments with extensive bone loss in master casts

A post-impression preparation technique can be used for preventing fracture of isolated abutments in master casts with extensive bone loss. This technique involves using a sharp knife to trim the impression obliquely at the clinical cervical line, creating a 1- to 2-mm-width bevel, followed by the insertion of a dowel pin into the abutment for reinforcement. This technique enlarges the abutments' diameter at the clinical cervical line and increases the resistance to breakage without altering the shape of critical areas.

A method for quantifying complete denture quality

STATEMENT OF PROBLEM

Reproducible and quantitative clinical evaluation of complete denture prostheses is of great importance for preoperative diagnosis, treatment planning, and assessment of quality of denture treatment.

PURPOSE

This study attempted (1) to clarify the degree of contribution each clinical factor made to the general assessment of experienced prosthodontists to complete denture prostheses, and (2) to develop a method for quantitative assessment of complete denture quality.

METHODS

Sixteen clinical factors with a three-grade scale were used to evaluate complete denture prostheses in 320 patients. The general assessment of the dentures was conducted with a 10-point scale. The contribution of each grade of the 16 factors to the general assessment level was determined by a multiple regression analysis.

RESULTS

Seven factors were highly correlated to the general assessment. On the basis of these significant contributions, a complete denture scoring method was established followed by the calculation of the category scores of these factors and conversion of the total sum of each category score to an integer number between 0 and 100. The resultant quantification score was closely correlated with the general assessment of the denture.

CONCLUSION

An evaluation protocol used for scoring of complete dentures was developed based on the scientifically analyzed knowledge of experienced prosthodontists.

Self-assessed masticatory ability in relation to maximal bite force and dental state in 80-year-old subjects

By means of a questionnaire, clinical examination and force recordings, the relationships between self-assessed masticatory ability, dental state and bite force were studied in 160 80-year-old persons, 74 men and 86 women. The subjects were in general satisfied with their masticatory ability and 70% had no problems, while 6% reported three or more problems with mastication. Half of the subjects were dentate without removable prostheses and almost one-third had 20 or more natural teeth. The edentulous persons (about one-fifth of all) reported more problems related to mastication than the other dentition groups. The maximal bite force varied much and exhibited a significant correlation to the number of remaining teeth and dental state. The self-assessed masticatory ability was only weakly correlated with dental state and bite force. It was concluded that many subjects with few or no remaining teeth and/or removable dentures had only few complaints of impaired masticatory function and showed a good adaptation to an impaired dental status and small maximal bite force.

Sex difference of electromyogram of masticatory muscles and mandibular movement during chewing of food

The aim of this study was to investigate whether there were sex differences in the electromyograms (EMG) of the masticatory muscles and in the mandibular movement of young adults when chewing food. Twenty subjects with normal dentitions were selected. The 11 test foods selected were all easily available in Japan. The results showed firstly that although there were no significant differences of chewing frequency between males and females, females chew food more slowly with less masticatory force and narrower mouth opening width than males; and secondly it appears that the chewing function in females is lower than in males.

Associations between self-assessed masticatory ability and some general health factors in a Swedish population

OBJECTIVES

The aims of this study were 1) to describe changes in self-assessed masticatory ability over a 14 year period (1975-89); and 2) to describe associations between self-assessed masticatory ability and age, dental state and some other background factors in a sample of the Swedish population in 1988/89.

DESIGN

The Swedish National Central Bureau of Statistics investigates annually the living conditions of the Swedish population by means of interviews by trained persons. The data were analysed by means of stepwise logistic regression and calculation of adjusted relative risks.

SUBJECTS

In the investigation in 1988/89, 12,901 people above 16 years of age participated and the response rate was 80%.

RESULTS

In comparison between the investigations, the prevalence of reported impairment was lower in 1988/89 than in 1975 and 1980/81. Prevalence of reported impairment of chewing ability increased with ageing from 2% in young adults (16-34 years old) to 44% in older elderly (> 85 years old). In most age groups, edentulous people reported the highest prevalence, and dentate people the lowest. Relative risks for impaired masticatory ability, independent of age, gender and dental state, were higher for people in rural areas, with low income and living single, as well as for those with skeletal, gastrointestinal, psychiatric and tumour diseases. In the elderly, results from the logistic regression showed that some disability and psychosocial factors were also associated with masticatory ability.

CONCLUSIONS

The results indicated that there was a group of elderly people who reported several functional and health problems including impaired masticatory ability.

Reproducibility of tooth tapping rhythm in young and elderly dentate subjects

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 15 s 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.

[A study on mandibular incisal point movement of TM disorder patients]

In order to establish diagnostic and treatment system for temporomandibular (TM) disorder patients, data were collected on mandibular border and tapping movements at incisive point and compared with those from the subjects without any TM disorders. Significant differences on the ratio of left and right sides of maximum lateral deviation, maximum opening amount and length of pathway of lateral border movement were clearly obtained, the values of maximum speed and acceleration of closing phase in tapping movement obtained from TM disorder patients were also different significantly from those in the control subjects. These findings suggests that those measured indices in this study would be useful for diagnosis of TM disorders.

[Tooth tapping frequency of young and elderly subjects]

Tooth tapping frequency was measured in young (21-29 years) and elderly (61-67 years) subjects. They were asked to continue the maximal frequent tapping during 1 min., and their mandibular movement were measured with a Mandibular Kinesiograph. The results are as follows: 1. Each phase of closing, occluding, opening and cycle was prolonged at the terminal of the 1 min. tapping. That is, tapping frequency decreased. Young subjects had 4.6 Hz tapping frequency and 2.7 Hz for elderly subjects. 2. Although the opening phase per cycle and the closing were not changed in spite of the tapping continuity, the occluding one increased at the terminal of the 1 min. tapping. 3. No difference existed between the young subjects and elderly in the maximal velocity of the mandibular movement at the opening and closing. Opening velocity was larger than closing velocity at the young subjects.

[Electromyographic study on masticatory function of the telescope denture wearers in the Kennedy Class II mandible]

Masticatory function of 10 telescope denture wearers in the Kennedy class II mandible patients was evaluated with electromyography. Electromyographic activity during mastication with kamaboko and peeled raw carrot was recorded from bilateral masseter and the anterior part of temporal muscles at each interval: Before treatment, immediately after denture insertion and 2, 4, 6, 8 weeks after respectively. Mean of duration, interval and cycle of EMG activities, coefficient of variation and average variation were calculated. The results were as follows: 1. Means of duration and cycle times decreased immediately to 2 weeks after denture insertion. 2. EMG activities during raw carrot chewing became regular immediately to 2 weeks after denture insertion, and within 4 weeks in kamaboko chewing. These results suggest that telescope dentures would be adapted to stomatognathic system within short period after denture insertion.

A short-term evaluation of the effectiveness of stabilization-type occlusal splint therapy for specific symptoms of temporomandibular joint dysfunction syndrome

To clarify the short-term effectiveness of stabilization-type occlusal splint therapy, a specific symptom approach was used toward 30 temporomandibular joint dysfunction patients with more than two major symptoms (temporomandibular joint and/or masticatory muscle pain, temporomandibular joint sounds, and limitation of mandibular movement). Eighty-seven percent of the patients with pain responded with this therapy and more than 50% had complete relief of pain 4 weeks after insertion of the splint. Temporomandibular joint sounds and limitation of mandibular movement responded more slowly than pain. These results suggest that the stabilization-type occlusal splint should be selected as a first choice among several therapies and that temporomandibular joint pain is particularly susceptible to this therapy.