Bolus delivery of palonosetron through skin by tip-loaded dissolving microneedles with short-duration iontophoresis: A potential strategy to rapidly relieve emesis associated with chemotherapy.

The objective of this study was to investigate the feasibility of the bolus administration of PLS via skin by using dissolving microneedles of palonosetron hydrochloride (PLS-DMNs). Tip-loaded PLS-DMNs were fabricated by a casting method using sodium hyaluronate (HA) as DMNs-forming polymer. PLS-DMNs were shown to have a content of 118.5 ± 8.7 µg per piece with sufficient mechanical strength for insertion into pig skin ex vivo. In situ dissolution of PLS-DMNs was achieved within 5 min and 83.2 % of PLS was delivered. In vitro studies showed that PLS-DMNs provided much higher PLS permeation than that after passive permeation using a PLS hydrogel. Moreover, the application of 30 min-iontophoresis at the beginning of PLS-DMNs administration further enhanced PLS delivery. In vivo pharmacokinetic studies were carried out in rats. The area under the curve (AUC) and the time to reach the peak (Tmax) after application of PLS-DMNs was not significantly different compared to those after subcutaneous (S.C.) injection. PLS-DMNs plus 30 min-iontophoresis enabled the pharmacokinetic profile to be even closer to that seen after S.C. administration. These results suggest that application of PLS-DMNs with short-duration iontophoresis exhibits promise as an alternative PLS delivery method that can be painlessly self-administered with rapid onset.

[Preliminary development of photoelastic resin occlusal film].

PURPOSE: To develop an occlusal film that can be intuitively and easily used clinically to observe the stress distribution of occlusion, based on the photoelastic resin material properties. METHODS: Using self-made silicone rubber vaginal mold, the epoxy resin occlusal films were poured into 2 different thickness and 4 different plasticizer ratio. The hardness and bitability were evaluated in 10 cases of natural dentition and 5 cases of complete denture dentition, while the bite blot was recorded using light bomb instrument at the same time. The data was analyzed and compared with T-Scan system. RESULTS: 2-50 occlusal film presented not only a right bite comfort, but also a clear response to occlusion blotting, which showed a comparable manifestation with T-Scan system. CONCLUSIONS: Compared with traditional inspection methods, occlusal photoelastic film can provide more intuitive occlusal stress distribution and benefit the diagnosis and efficacy evaluation of bite-related diseases. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2271100) and Shanghai Leading Academic Discipline Project (Grant No.T0202).

[Comparison of clinically used shade guide systems with color range of natural teeth].

OBJECTIVE: To analyze the limitation of currently used shade guide systems comparing with color range of nature teeth. METHODS: Digital pictures of shade guide systems A (VITAPAN Classic), B (VINTAGE Halo), C (3D-MASTER), and 322 central incisors were taken under the same condition as light source of D65 with the observation method of d/0 degrees. The data obtained from nature tooth color were compared with the color range of three shade guide systems mentioned above in items of L * a * b */C * H degrees. RESULTS: The normal chroma value (95%) of the natural teeth were L* 61.631-73.250, a * -0.719-1.879, and b * 8.701-17.790. Natural tooth colors were different from those of the shade guide system A which color range was narrower, short of red hue, higher values, and unevenly distribution of saturation. On the other hand, the range of red hue increased in shade guide system B while its saturation was slightly high. The color range of shade guide system C was greatest among the three shade guide systems. The saturation and value of shade guide system C covered all varieties of nature teeth measured in this research, but it still lacked red hue comparing to the nature teeth. CONCLUSIONS: Comparing the color range of nature teeth, the shade guide systems used in clinic have uneven hue distribution and cannot cover all colors of nature teeth. Generally, all the shade guide systems are lack of the hues which are named under the category of red tone.

[A primary study of color tolerance of anterior tooth crown prosthesis].

OBJECTIVE: To study the color tolerance of anterior ceramic crown and seek an effective approach for color-matching of oral prostheses. METHODS: 30 single maxillary incisor ceramic prostheses and the corresponding nature teeth were measured by a digital camera in a steady environment for image taking and color measurement, which based on the standard recommended by CIE. The color tolerance was analyzed in two groups based on satisfaction and dissatisfaction of prostheses color-matching. RESULTS: The deltaE of satisfaction group was 2.5503, while the deltaE of dissatisfaction group was 4.0772. There was significant difference between chromatic aberration of satisfaction group and dissatisfaction group (P<0.01). When the lightness and saturation of prosthesis were higher than nature teeth, there was no significant difference between deltaL*, deltab*, deltaC* of satisfaction group and dissatisfaction group (P>0.05). When the lightness and saturation of prosthesis were smaller than nature teeth, there was significant difference between deltaL*, deltab*, deltaC* of satisfaction group and dissatisfaction group (P<0.01). There was significant difference between deltaa*, deltaH of satisfaction group and dissatisfaction group (P<0.05, P<0.01). CONCLUSION: Control of color difference is the key for shade matching of anterior tooth prosthesis. Applying the color tolerance is beneficial to improving the prosthesis quality.

[A study of color measurement for vital teeth using digital camera].

PURPOSE: To evaluate the reliability and reasonability of tooth color matching by using the digital camera. METHODS: 322 maxillary incisors from 161 Asia volunteers aged between 20 to 40 years were recorded by a Canon EOS D60 digital camera in studio environment (D65 standard illuminant). Photographs were taken under a set exposure parameters( AE f/2.8, 1/45s, ISO 100) and saved in RAW image file format. The characteristics of color of the tested teeth were visually observed, and the color values were obtained from the digital images using Camera RAW for Adobe Photoshop 8.0 and quantified according to an internationally recognized scale as CIELAB color values, L*a*b*/C*H degrees . All data were analyzed in descriptive statistics and compared in Wilcoxon analysis using SAS8.1 software package. RESULTS: There were 49.8% of samples shown an uneven distribution of color, 14.1% had abnormal pigment. The color parameters of all tested vital teeth were: L*39.928-75.681, a*-1.543-5.8284, b*5.5764-22.591, the tolerance of deltaEab<2.8NBS. CONCLUSION: The assessment of vital tooth color depend on sort of measurement and instrument, however, the method of tooth shade matching by digital camera seems reliable and advantageous.

[The relationship between clasp retention and the depth of undercut].

OBJECTIVE: To study the relationship between the depth of undercut and the retention of clasp, as a basic information in clinic designing of clasp. METHODS: The Chatillon force measuring instrument was used to record the retention of 18 Co-Cr alloy casting Akers clasps when they were dislodging from undercuts of different depths (0.25 mm, 0.50 mm, 0.75 mm) on bicuspid and molar. All the data was analyzed by ANOVA. RESULTS: It is showed that the deeper the undercuts the greater the retention is. The retention of the clasp on molar is greater than premolar in the same condition of undercut. The effect of the types of the abutment and the depths of the undercut are both obvious on the retention of clasp. CONCLUSIONS: Within the elastic limit of the material, the retention of clasp and the depth of abutment undercut show a positive correlation.

[Circulating test and analysis of clasp retention].

OBJECTIVE: To show the trend of the retention change during the circulation of the clasp dislodging and inserting, and to discuss the proper depth of the undercut for a specific clasp. It is also a basic study for the best designing of RPD. METHODS: The Chatillon force measuring instrument was used to record the variation of the retention of Co-Cr alloy casting Akers clasp when they were dislodging from undercuts of different depths (0.25 mm, 0.50 mm, 0.75 mm) on bicuspid and molar. RESULTS: The data was analysed of Correlation and Regression by SPSS 10.0 statistic software. The variations of the retention in the circulation are obvious from the different teeth and different undercut depths. It shows an attenuation trend in circulation (P < 0.01). After 400 times dislodging, in bicuspid group, the retention of the clasp used in 0.50 mm undercut became less than the one used in 0.25 mm undercut. While the retention of the clasp used in 0.75 mm decreases most obviously, it values 0.7670 kg. In molar group, the attenuations of the retention at different depths of undercut are similar, the retentions of the clasp still rank as, from great to less, 0.75 mm, 0.50 mm and 0.25 mm, in the depth of undercut. CONCLUSION: the proper depth of the undercut for bicuspid is 0.25 mm, and 0.50 mm for molar.