Purpose: In prosthodontics like in other dental disciplines there are many clinical procedures that lack support of good evidence, which means that the effect is unknown, and even worse, we do not know if they do more good than harm. It is the aim of this paper to review current evidence for selected procedures based on a scrutiny of the prosthodontic literature.
Study selection: A MEDLINE/PubMed search was conducted for articles on the selected items with a focus on best available evidence.
Results: Many “old truths” regarding prosthodontic interventions can be called dogmas, opinions based more on belief than scientific evidence. There is, for example, lack of evidence to support the opinion that a face-bow is necessary in the fabrication of prostheses, and many theories related to occlusion are not evidence-based. Some such dogmas in various areas of the discipline are exemplified and discussed in the article.
Conclusion: A scrutiny of the prosthodontic literature indicates that many common clinical procedures lack scientific support. In the era of evidence-based dentistry, ineffective interventions should be eliminated and decisions should be made on best available evidence.

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Purpose: To clarify the masticatory path patterns of the mandibular incisal point during mastication of softened chewing gum with regard to gender difference.
Methods: One hundred healthy subjects (50 males and 50 females) were asked to chew softened chewing gum on one side at a time (right side and left side) and the movement of the mandibular incisal point was recorded usingMKGK6I. After a catalog of path patterns was made, the movement path was classified into one of the pattern groups, and then the frequency of each pattern was investigated.
Results: A catalog of path patterns consisting of the three types of opening path (op1, linear or concave path; op2, path toward the chewing side after toward the non-working side; op3, convex path) and two types of closing path (cl1, convex path; cl2, concave path) was made. The movement path was classified into one of seven patterns, with six patterns being from the catalog and a final extra pattern in which the opening and closing paths crossed. The most common pattern among the subjects was Pattern I, followed by Patterns III, II, IV, V, VII, and VI, in that order. The majority of cases, 149 (74.5%) of 200 cases, showed either Pattern I (op1 and cl1) or Pattern III (op2 and cl1). There was no significant difference between the two genders in the frequency of each pattern.
Conclusion: The movement path could be classified into seven patterns and no gender-related differencewas found in the frequency of each pattern.

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Purpose: To develop a system to measure the pressure distribution under the base of a removable partial denture (RPD) and to apply it in vivo.
Methods: A tactile sensor sheet with 100 sensing points and a measuring system (I-SCAN™, Nitta, Osaka, Japan) were used. The sensor was calibrated before being applied in vivo. A subject with a mandibular RPD (Kennedy class II, division 1) participated in this study, and the RPD was duplicated as the experimental denture. The basal surface at distal extension was accommodated to the sensor in a manner similar to direct relining. Measurements were performed with three patterns of occlusal rest design (mesial and distal rests, mesial rest only, and without a rest) during maximal voluntary clenching (MVC) and gum chewing.
Results: The calibration measurements showed that the output value from each sensing point and total output of sensing points were positively correlated with the applied load. The pressures recorded in vivo varied depending on the locations of sensing points on the basal surface of the denture. During MVC the pressure distribution changed with the clenching level, and the highest pressure was registered near the residual ridge crest. The pressure distribution also changed according to the number of occlusal rests. The load center shifted about 2 mm during MVC and about 4 mm during gum chewing.
Conclusion: The measuring system developed here enabled us to measure the pressure distribution under the denture base of RPD. The pressure distribution varied along with the design of the occlusal rest.

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Purpose: To elucidate the influence of motion and posture of head on the newly developed ultraminiature cordless bruxism measurement system (BMS), we examined masseteric electromyographic (EMG) data of BMS during turning-over movements in bed in comparison with those of a conventional polygraph system (PG).
Methods: Twelve healthy subjects lay on their back and then turned to the right (right turn, 90°) and then to the left (left turn, 180°). Maximum amplitudes and root mean square (RMS) values of EMG data were calculated during the phase of turning movements. The data were high-pass filtered at 10 Hz, 30 Hz, 50 Hz, and 100 Hz.
Results: Artifact signals were visibly observed in PG measurement for all subjects and in BMS measurement for three subjects. Maximum amplitudes during right turn measured by BMS were significantly smaller than those measured by PG, while there was no significant difference during left turn. During right turn, RMS values high-pass filtered at 10 Hz obtained by BMS were significantly smaller than those obtained by PG, while there was no significant difference between the data obtained by the two devices at the other cut-off frequencies. During left turn, there was no significant difference between RMS values obtained by the two devices.
Conclusions: Although BMS data were slightly affected by motion and posture of head during simulated sleep-turning, it was suggested that motion artifact of signals during BMS measurements is equivalent to or less than that during PG measurements, and BMS is thought to be suitable to measure sleep bruxism.

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Purpose: The aim of this study was to develop a sensor sheet for measuring tongue pressure during swallowing and to clarify its usefulness by comparing it with a conventional pressure sensor installed in the palatal plate.
Methods: A tactile sensor system was used for the construction of the measuring system. Based on our preceding study, a T-shaped sensor sheet with 0.1 mm thickness, five measuring points (three points on the median line, two points on the posterior-lateral part) and three sizes based on the morphological analysis of 60 maxillary casts was designed for application on the hard palate. To elucidate the sensing characteristics of the sensor sheet, the output level of the sensor sheet was compared with that of a conventional pressure sensor under the same load. The maximal magnitude of tongue pressure (MP) during the swallowing of 15 ml water was recorded by a sensor sheet attached to the palatal mucosa and was compared with that recorded by pressure sensors installed in the palatal plate.
Results: The output level of the sensor sheet was smaller than that of the pressure sensor. There was a high correlation between the output levels of the two sensors (R = 0.952, P < 0.001). Although MP at each sensing point of the sensor sheet was also smaller than that recorded by the pressure sensors, MP collected by the regression equation obtained in our experiment was quite similar to that for the pressure sensors.
Conclusions: This system could be useful for evaluating tongue activity during oropharyngeal swallowing.

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Purpose: The purpose of this study was to evaluate a newly developed method to construct customized finite element models from the viewpoints of the accuracy of measurement and the reproducibility of calculated denture movement under loads.
Methods: A cast of an edentulous mandibular alveolar ridge and a waxed complete denture were used. Measurement of the surface was done using a 3D-digitizer. After superposing, they were rotated so that the occlusal plane became level. The border of the alveolar ridge on the cast was decided in each buccolingual section. From a series of cross sections, the surface of the alveolar ridge was made. Based on the surfaces of the mucosa and denture, a finite element model consisting of the denture and underlying mucosa, which was given a uniform thickness, was constructed. This procedure and analysis under bilateral or unilateral loads on an artificial molar region were done repeatedly to evaluate its reproducibility and the error of the measurement of the surface.
Results: The standard error of the measured shapes of spheres was estimated to be within 0.1 mm. The error caused by superposing was estimated to be within 0.38 mm. The results of analysis showed that the coefficient of variation of the displacement of the denture at selected nodes was approximately 14.1% at most.
Conclusions: We conclude that this method has sufficient measurement accuracy and reproducibility for the calculated movement of dentures.

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Purpose: This study aimed to determine the influence of the thickness of a palatal plate on the mandibular position during continuous phonation of the sound [n].
Methods: Eleven healthy volunteers (10 males and 1 female; 24-36 years of age, mean age 26.4 years) were recruited from dental students. They were instructed to pronounce [n] continuously under six conditions: wearing a palatal plate with a thickness of 0.3, 1.5, 3.0, 5.0, and 10.0 mm, and without a plate (control). Mandibular movement during pronunciation was simultaneously recorded by a K-7 mandibular kinesiograph. Their mandibular positions in the physiologic rest position were also recorded. The distance between the incisal edge of maxillary and mandibular anterior teeth both in vertical and antero-posterior directions during continuous phonation of [n] (interocclusal distance) under all six conditions were measured and compared.
Results: Interocclusal distance tended to increase in both vertical and antero-posterior directions as the thickness of the palatal plates increased. There were statistically significant differences in the mandibular position both in vertical and antero-posterior directions during continuous phonation of [n] between the control condition and those wearing a palatal plate with a thickness of 10.0 mm.
Conclusion: The mandibular position determined by the phonetic method employing continuous [n] as a test pronunciation was affected by the thickness of the palatal plates inserted into the mouth. However, its influence was not significant when the thickness of the palatal plates was 5 mm or less.

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Purpose: The purpose of this study was to compare the effectiveness of fast and slow biodegradation of basic fibroblast growth factor (bFGF)-gelatin hydrogel complex on bone regeneration around fenestrated implants as a new augmentation drug delivery system.
Methods: Nine titanium implants (3.3 mm diameter and 10 mm length) were placed into the edentulous areas of the mandibles of three adult beagle dogs with four screws exposed at the upper buccal side. The effectiveness of bFGF-gelatin hydrogel complexes of varying degradation types used to cover implant screws without membrane were compared with 1 μg and 10 μg bFGF-98 wt% gelatin as the fast degradation type and 10 μg bFGF-95 wt% gelatin as the slow degradation type. After 4 weeks, bone regeneration around the screws was evaluated histologically and histomorphometrically.
Results: With use of 10 μg bFGF, regenerated bone around exposed screws was clearly seen in both the fast and slow degradation type groups. In contrast, little bone formation was seen in the fast degradation-type group with 1 μg bFGF. Height of regenerated bone for the slow degradationtype complex group was significantly greater than for the fast degradation-type group with 1 μg bFGF (P < 0.05).
Conclusion: These results suggest that use of slow degradation-type bFGF-gelatin hydrogel complex may accelerate bone regeneration around fenestrated implants at an early stage of bone regeneration.

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Purpose: To clarify the usefulness of the standard deviation (SD) and SD divided by the opening distance (SD/OD) of the opening lateral, closing lateral, and vertical components of the masticatory path as indicators of the stability of masticatory movement path.
Methods: Fifty subjects masticated softened chewing gum on the unilateral side for 20 s, and the movement of the mandibular incisal point was recorded. For 10 cycles from the 5th cycle of 100 cases (50 subjects chewing on either side), a picture comprising each cycle path was displayed and classified subjectively into three categories (stable, unstable, and unknown) by three evaluators. The 18, 17, and 19 cases that were assessed as stable, unknown, and unstable were classified as Groups A, B, and C, respectively. For 10 cycles from the 5th cycle, the SD and SD/OD of the opening lateral, closing lateral, and vertical components representing the movement path as indicators for the stability of the path were calculated and compared among the three groups.
Results: The SD and SD/OD of the opening lateral, closing lateral, and vertical components were small in Group A, increased in Group B, and increased further in Group C. Significant differences were observed among the groups. These differences were more apparent in the assessment using the SD/OD than in the assessment using the SD.
Conclusion: The SD and SD/OD of the components representing the movement path were useful as indicators for the stability of the movement path and the SD/OD appeared to be particularly useful.

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