Chronic Hypoxemia Triggers a Neuropathic Process in Chronic Obstructive Pulmonary Disease:Insight From In Vivo Neurophysiological Assessments

Background@#and PurposePeripheral neuropathies (PNs) are a common but poorly understood complication of chronic obstructive pulmonary disease (COPD). To clarify the initial trigger of a PN in COPD, we investigated the excitability of peripheral nerves in patients with COPD. @*Methods@#The automated nerve excitability test (NET) using the threshold-tracking paradigm was applied to 20 COPD patients. The recording protocol calculated the strength–duration time constant, threshold electrotonus (TE), current–threshold relationship, and recovery cycle (RC). Each NET parameter was compared with two control groups: normal controls group (NC group) and smokers without COPD group (smoker group). @*Results@#In the motor NETs, the change in the threshold in the mid-depolarizing phase of TE (40–60 ms) was smaller in the COPD group (50.7%±1.2%, mean±SEM; n=20) than in the NC group (54.5%±0.7%, n=25; p<0.01), as was the prominence of superexcitability in the RC (-22.6%±1.5% and -26.4%±1.1%, respectively; p=0.04). There were no significant differences in the sensory NETs. Comparisons between the COPD and smoker groups (n=25) also showed no differences in either the motor or sensory NETs. @*Conclusions@#The pattern of excitability in COPD revealed a membrane depolarization attributable to Na+–K+–ATPase failure in the axolemma of distal motor nerves. This finding suggests that chronic hypoxemia and adaptative process can alter axonal excitability and trigger a resultant neuropathic process that is antecedent to PN in COPD.

Enhanced Bone Formation by Rapidly Formed Bony Wall over the Bone Defect Using Dual Growth Factors

BACKGROUND@#In guided bone regeneration (GBR), there are various problems that occur in the bone defect after the wound healing period. This study aimed to investigate the enhancement of the osteogenic ability of the dual scaffold complex and identify the appropriate concentration of growth factors (GF) for new bone formation based on the novel GBR concept that is applying rapid bone forming GFs to the membrane outside of the bone defect. @*METHODS@#Four bone defects with a diameter of 8 mm were formed in the calvaria of New Zealand white rabbits each to perform GBR. Collagen membrane and biphasic calcium phosphate (BCP) were applied to the bone defects with the four different concetration of BMP-2 or FGF-2. After 2, 4, and 8 weeks of healing, histological, histomorphometric, and immunohistochemical analyses were conducted. @*RESULTS@#In the histological analysis, continuous forms of new bones were observed in the upper part of bone defect in the experimental groups, whereas no continuous forms were observed in the control group. In the histomorphometry, The group to which BMP-2 0.5 mg/ml and FGF-2 1.0 mg/ml was applied showed statistically significantly higher new bone formation. Also, the new bone formation according to the healing period was statistically significantly higher at 8 weeks than at 2, 4 weeks. @*CONCLUSION@#The novel GBR method in which BMP-2, newly proposed in this study, is applied to the membrane is effective for bone regeneration. In addition, the dual scaffold complex is quantitatively and qualitatively advantageous for bone regeneration and bone maintenance over time.

Finite element analysis of the effect of novel Lock Screw system preventing abutment screw loosening

PURPOSE: The purpose of this finite element analysis study is to introduce the novel Lock screw system and analyze its mechanical property to see if it can prevent abutment screw loosening. MATERIALS AND METHODS: The Lock screw is a component tightened on the inside of the implant abutment which applies compressive force to the abutment screw head. To investigate the effect, modeling was done using CAD program and it was analyzed by finite element analysis under various load conditions. First, the preload was measured according to the tightening torque of the abutment screw then it was compared with the theoretical value to verify the analytical model. The validated analytical model was then divided into those with no external load and those with 178 N, and the tightening torque of the lock screw was changed to 10, 20, 30 Ncm respectively to examine the property of stress distribution on the implant components. RESULTS: Using Lock screw under various loading conditions did not produce equivalent stresses beyond the yield strength of the implant components. In addition, the axial load was increased at the abutment-abutment screw interface. CONCLUSION: The use of Lock screw does not exert excessive stress on the implant components and may increase the frictional force between the abutment-abutment screw interface, thus it is considered to prevent loosening of the abutment screw.

Use of digital scan data for evaluation of edentulous ridge relationship: A case report for removable prosthesis with unilateral cross bite / 대한치과보철학회지

After the teeth were extracted, maxillary and mandibular alveolar ridges show the opposite resorption pattern and as a result, the mandibular arch is enlarged than maxillary arch relatively. In this situation, we should evaluate both alveolar ridge relationship and arrange the artificial teeth properly for stability of removable prosthesis. This case is a 77 years old male patient who wishes to make removable prosthesis and has atrophic alveolar ridge. By use of model scanner and CAD software, the angle between interalveolar crest line and occlusal plane was easily measured. Depending on the measurement, the artificial teeth are arranged in unilateral cross bite and after completion, patient was satisfied with the denture which showed proper stability, retention, support.

Analysis of longevity and success rate of fixed, removable, and implant prostheses treated in Korea / 대한치과보철학회지

PURPOSE: The purpose of this study is to analyze the factors affecting the longevity of failed prosthesis and the success rate of the prosthesis based on the data evaluated with the newly developed Korean Academy of Prosthodontics (KAP) criteria. MATERIALS AND METHODS: Evaluation was performed in the restored prosthesis for patients who visited the prosthodontics department of the 13 dental university hospitals and general hospitals. The status of the prosthesis was classified into four categories: Good, Fair, Bad, Worst. The success was recorded if only the category was classified in ‘good’. The mean duration of failed prostheses and the success rate through Kaplan-Meier method were analyzed. RESULTS: A total of 1,804 cases of prosthesis were evaluated: 810 cases of fixed dental prostheses (FDP), 519 cases of Removable Dental Prostheses (RDP), and 475 cases of implant prosthesis. The mean duration of failed FDP was 11.41 ± 0.30 years and the median was 10 years. The mean duration of failed RDP was 8.18 ± 0.29 years and the median was 7 years. The mean duration of failed implant prosthesis was 7.99 ± 0.30 years and the median was 7 years. The factors related to the failure were as follows: number of units, abutments, abutments treated with root canal, and plaque index in FDPs; treated and opposing dentition in RDPs; the number of implants, duration of use, and plaque index in implant prostheses. CONCLUSION: The average duration of failed prosthesis was 11.41 years for FDPs, 8.18 years for RDPs, and 7.99 years for implant prosthesis, according to the evaluation with newly developed KAP criteria.

Fabrication of palatal lift prosthesis for a patient with palatal defect / 대한치과보철학회지

This report is a case of 38-year old female patient who had a chief complaint about having pronounciation disorder after going under mass excision due to mucoepidermoid carcinoma. She was referred to department of prosthodontics, Yonsei university. Palatal lift prosthesis was fabricated which was then relined with tissue conditioner. Evaluations on phonetics and swallowing were done and improvements were shown. Tissue conditioner was replaced with heat polymerizing resin and the patient was satisfied with the results of treatment.

The evaluation of the shear bond strength between various Hybrid CAD/CAM restorative materials and repairing composite resins / 대한치과재료학회지

The purpose of this study was to evaluate the shear bond strengths between various hybrid computer-aided design (CAD)/computer-aided manufacturing (CAM) restorative materials and repairing resin. Two resin network-based hybrid (Lava Ultimate and Polyglass), one ceramic framework-based hybrid (Enamic), and one zirconia (Zenotec Zr bridge) CAD/CAM restorative materials were used in this study. The shear bond strength test and failure modes of four experimental groups designated LUS (Lava Ultimate), ENA (Enamic), PGB (Polyglass), and ZBR (zirconia control group) were characterized in this study. The hybrid CAD/CAM restorative materials showed stronger shear bond strengths in the sequence of PGB, LUS, and ENA (P < 0.05). The shear bond strengths of PGB and LUS groups showed significantly higher than those of ZBR (P < 0.05), while ENA did not show any significant difference from ZBR (P < 0.05). The PEG and LUS groups mostly exhibited cohesive failure, but the ENA and ZBR groups predominantly showed adhesive failure. Therefore, resin network-based hybrid CAD/CAM restorative materials such as Lava Ultimate and Polyglass should be more useful for intra-oral repairs.

Titanium-zirconium alloy narrow-diameter implants for the rehabilitation of horizontally deficient mandibular posterior edentulous ridges / 대한치과보철학회지

In case of the insufficient horizontal bone loss, a regular diameter implant is not possible without lateral bone augmentation. In this situation, narrow diameter implants (NDIs) could be the alternative to lateral bone augmentation procedures. However, complication generally expected with the NDI is implant fracture. Recently, the survival rate and success rate of NDI in the posterior region are similar to that of standard-diameter implants (SDIs). These 3 case reports demonstrate the incorporation of NDI to replace missing mandibular posterior teeth. So far, the follow-up examination period was maintained and no unusual complications were presented for more than four years. Long term follow-up clinical data are needed to confirm the excellent clinical performance of these implants.

Influence of internal connection length on screw loosening in internal connection implants / 대한치과보철학회지

PURPOSE: The purpose of this study was to evaluate whether the internal abutment length affected screw stability in an internal connection implant. MATERIALS AND METHODS: Twenty long internal connection implants (Replus system, 4.7 × 11.5 mm) were selected for this investigation. Abutments were assigned to four groups depending on the length of the internal connection (abutments with internal lengths of 1, 2, 3, and 4 mm, respectively). Each implant fixture specimen was embedded in resin medium and connected to an abutment with an abutment screw. A load of 100 N, applied at an angle of 30° to the long axis of the implant, was repeated for 1.0 × 10⁶ cycles. Reverse torque values (RTV) were recorded before and after loading, and the change in RTV was calculated. Data were analyzed with the Kruskal-Wallis test. RESULTS: The change in RTV was not significantly different among the groups (P>.05). Screw loosening and fractures were not observed in any groups, and joint stability was maintained. CONCLUSION: The internal length of the abutment may not significantly affect the degree of screw loosening.

Comparison of shearbond strength between metal and indirect resin according to the different conditionings / 대한치과보철학회지

PURPOSE: The purpose of this study is to investigate the differences in bond strength of four different indirect composites to the gold alloy and Ni-Cr alloy according to type of metal surface treatment after water storage. MATERIALS AND METHODS: Type IV gold alloy and Ni-Cr alloy were used for casting alloy while four types of indirect composite resins (Gradia, Tescera Sinfony and in;joy) were used in this study. Metal specimens were produced by casting and total of 240 specimens (60 specimens per one indirect composite group) were prepared. After bonding indirect composite resin and undergoing 24 hours of polymerization, customized jig was attached to the metal specimen and shear bond strength were measured using universal testing machine. Also, differences in shear bond strength before and after water storage for 240 hours were also measured. RESULTS: In the measurement of shear bond strength according to the metal surface treatments, bead group showed high strength followed by loop and flatting group (P<.05). After being stored in water bath for 240 hours, Gradia showed statistically significant high bond strength compared to other indirect composite resins in all groups (P<.05). CONCLUSION: Shearbond strength was found to be different according to type of metal surface treatment and type of metal used after storage in water. Further studies need to be developed for clinical practices as three are still problems of microleakage, stain or wear.

Evaluation of stability of interface between CCM (Co-Cr-Mo) UCLA abutment and external hex implant

PURPOSE: The purpose of this study is to evaluate the stability of interface between Co-Cr-Mo (CCM) UCLA abutment and external hex implant. MATERIALS AND METHODS: Sixteen external hex implant fixtures were assigned to two groups (CCM and Gold group) and were embedded in molds using clear acrylic resin. Screw-retained prostheses were constructed using CCM UCLA abutment and Gold UCLA abutment. The external implant fixture and screw-retained prostheses were connected using abutment screws. After the abutments were tightened to 30 Ncm torque, 5 kg thermocyclic functional loading was applied by chewing simulator. A target of 1.0 × 10⁶ cycles was applied. After cyclic loading, removal torque values were recorded using a driving torque tester, and the interface between implant fixture and abutment was evaluated by scanning electronic microscope (SEM). The means and standard deviations (SD) between the CCM and Gold groups were analyzed with independent t-test at the significance level of 0.05. RESULTS: Fractures of crowns, abutments, abutment screws, and fixtures and loosening of abutment screws were not observed after thermocyclic loading. There were no statistically significant differences at the recorded removal torque values between CCM and Gold groups (P>.05). SEM analysis revealed that remarkable wear patterns were observed at the abutment interface only for Gold UCLA abutments. Those patterns were not observed for other specimens. CONCLUSION: Within the limit of this study, CCM UCLA abutment has no statistically significant difference in the stability of interface with external hex implant, compared with Gold UCLA abutment.

Korea Academy of Prosthodontics criteria for longevity studies of dental prostheses / 대한치과보철학회지

PURPOSE: The most important factor in longevity studies of dental prostheses is objective and consistent evaluation of the prosthesis. The Korean Academy of Prosthodontics suggested developing a standardized method for longevity studies of dental prostheses. The purpose of this study is to evaluate previously-used criteria and to develop new criteria, in the form of a procedure flowchart and an evaluation sheet. These new criteria may be able to provide a unified standard for future longevity studies of dental prostheses. MATERIALS AND METHODS: A literature review was performed about the evaluation of dental prostheses. Taking into account the strengths and weaknesses of previously used criteria, a novel, intuitive and objective method was developed for assessment of dental prostheses. Then, a pilot survey was performed with the newly developed flowchart and evaluation sheet to determine problems and implement possible improvements. RESULTS: Thirty cases of fixed dental prosthesis (FDP), 25 cases of removable dental prosthesis (RDP), and 13 cases of implant supported prosthesis (ISP) were evaluated. The average life expectancy estimate was 12.82 years for FDP, 5.96 years for RDP, and 4.82 years for ISP with Kaplan-Meier survival analysis. Additionally, possible improvements discovered by the pilot survey were reflected in the flowchart and evaluation sheet. CONCLUSION: The newly developed KAP criteria, flowchart and evaluation sheet enabled objective and consistent results in trial longevity studies of dental prostheses. It is expected that future studies will not only use the KAP criteria but also further improvement will be made on them.

Comparison of crown designs of different dental occupational groups, using CAD-CAM / 대한치과보철학회지

PURPOSE: Increasing use of computer aided design-computer aided manufacturing (CAD-CAM) system and number of design software made design of restoration easy and quick. Outcome of restoration has been dependent on dental technician's wax up proficiency, dentists can design restoration for themselves now. This study aims to investigate the outcome of restoration designs, according to handling skill of CAD-CAM design tool. MATERIALS AND METHODS: A patient's mandibular right 1st molar was prepared. After taking impression, stone model was made, scanned the stone model with 3 shape intra-oral scanner, stereolithography (STL) file was extracted. With 3shape dental designer, one dental technician with more than 5 years work experience (designer 0) and three dental technicians with less than 2years work experience (designer 1, 2, 3-group DT) and 4 1st year residents (designer 4, 5, 6, 7-group RT) designed gold crown on the same STL file. Designed crown's MD (mesio-distal) and BL (bucco-lingual) diameter, height of crown, inter-cuspal distance, number of occlusal contact points were compared. Statistical analysis was carried out, test of normality within each group, using independent t-test. Number of contact points were compared, using Wilcoxon signed-rank test. RESULTS: There was no significant difference between group DT and group RT. Number of contact points also resulted in no significant difference. CONCLUSION: The outcome of each designed crowns showed no statistical differences, in values which can be expressed as numbers. Subjective factors were different. With increasing proficiency in handling designing software, fabrication of restorations according to each designer's occlusal concept can be made easy.

Fabrication of palatal lift prosthesis using thermoplastic resin for a patient with velopharyngeal insufficiency / 대한치과보철학회지

Recently, flexible removable prosthesis with thermoplastic resin clasp has increasingly become popular. In comparison with conventionally used acrylic resin, thermoplastic resin has lower flexural strength and elastic modulus. Thus, flexible removable prosthesis has low risk of fracture, so denture base can be made thin and light, increasing patient comfort. Also, it can passively sit at tooth undercut during rest, so abutment teeth need minimum or no preparation. In this case report, a 44 year old female patient with mild velopharyngeal insufficiency was treated with a palatal lift prosthesis made of polyester thermoplastic resin. Since the patient had no missing tooth and desired conservative treatment, the flexible removable prosthesis provided relatively satisfactory results.

Intrusion phenomenon of natural tooth bounded by implant-prostheses: a clinical report / 대한치과보철학회지

In case of implant-tooth connected prosthesis, a natural tooth tends to intrude. There are several mechanisms that explain an intrusion phenomenon. So it is reco mmended not to connect an implant with a natural tooth. A 68-year-old female had upper left 2nd premolar and 2nd molar extracted and underwent implant surgery on the missing area. We made an implant prosthesis and treated upper left 1st molar with a gold crown. 2.5 year later, the patient complained about loose proximal contact and food impaction between upper left 1st molar and 2nd molar. Mesial side of upper left 2nd molar implant prosthesis was soldered so that proximal contact became tight again. But after 7 months, about 2 mm intrusion of upper left 1st molar occurred, and the patient felt periodontally originated pain on intruded upper left 1st molar. After the gold crown on upper left 1st molar was removed, extrusion occurred and pain was relived.

The effects of desensitizing agents, bonding resin and tooth brushing on dentin permeability, in vitro / 대한치과보철학회지

PURPOSE: The effects of desensitizing agent are often for a short duration. One of the reasons is believed to be wear of desensitizing agent by tooth brushing. To reduce the wear and make the duration longer, dental bonding resin was applied and the changes of dentin permeability after toothbrushing were measured. MATERIALS AND METHODS: Extracted teeth free from caries were chosen. Coronal dentin discs with thickness of 1 mm were prepared. Using the split chamber device developed by Pashely, hydraulic conductance and scanning electron microscope images (SEM) were compared and contrasted before and immediately after the application of desensitizing agent and bonding resin and then after equivalent tooth brushing of 1 week, 2 weeks, and 6 weeks. Four commercially available desensitizing agents were used in this study; they were All-Bond 2, Seal & Protect, Gluma, and MS Coat. And Dentin/Enamel Bonding resin (Bisco Inc.) was used. The results of this study are as follows. RESULTS: On all specimens, the hydraulic conductance decreased after the application of tooth desensitizing agent and bonding resin. Compared with the specimens treated only with desensitizer, the specimens treated with All-Bond 2, Gluma, MS Coat and plus D/E bonding resin had a little increase in hydraulic conductance after 1, 2 and 6-week tooth brushing. In case of Seal & Protect, the specimens showed the same result only after 6-week tooth brushing. On examination of SEM, the dentinal tubule diameter had decreased after treatment of desensitizing agents and bonding resin. And the specimens treated with All-Bond2, Seal&Protect, Gluma, MS Coat and plus D/E bonding resin had an significant decrease in diameter of dentinal tubule after 6-week tooth brushing. CONCLUSION: According to the results of this study, it is effective to use bonding resin after application of desensitizer in reducing the wear by tooth brushing and making the duration longer. In this study, just 6-week tooth brushing was performed, and it is not enough to regard it as a long-term data. So further study is needed and more perfect method for treating dentin hypersensitivity should be developed.

Morphometric analysis of maxillary alveolar regions for immediate implantation

PURPOSE: The purpose of this study was to provide an actual guideline in determining the shape, diameter, and position of the implant in immediate implantation by the measurement of the thickness of facial and palatal plate, the thickness of cortical bone on the facial and palatal plate, the diameter of the root, and the distance between the roots in the cadavers. MATERIALS AND METHODS: The horizontal sections of 20 maxillae were measured and analyzed to obtain the average values. Resin blocks were produced and cut serially at 1 mm intervals from the cervical line to the root apex. Images of each section were obtained and the following measurements were performed: The thickness of the facial and palatal residual bone at each root surface, the thickness of the facial and palatal cortical bone at the interdental region, the diameter of all roots of each section on the faciopalatal and mesiodistal diameter, and the interroot distance. Three specimens with measurements close to the average values were chosen and 3-dimensional images were reconstructed. RESULTS: The thickness of the facial and palatal cortical bone at the interdental region in the maxilla, the buccal cortical bone was thicker in the posterior region compared to the anterior region. The interroot distance of the alveolar bone thickness between the roots increased from anterior to posterior region and from coronal to apical in the maxilla. CONCLUSION: In this study, the limited results of the morphometric analysis of the alveolar ridge using the sections of maxilla in the cadavers may offer the useful information when planning and selecting optimal implant for immediate implantation in the maxilla.

The effect of alendronates administration duration on the healing of extraction socket in rats: pilot study / 대한치과보철학회지

PURPOSE: The purpose of this study was to investigate the effect of different administration duration of alendronate on initial wound healing and new bone formation of extraction socket in rats. MATERIALS AND METHODS: Fifteen male Sprague-Dawley rats (body weight 130-140 g, 4 weeks old, male) were divided into control group (no alendronate administration) and experimental group (alendronate administration). Experimental group was subdivided into 1 week administrated group, 2 week administrated group, 4 week administrated group and 6 week administrated group according to duration of administration. For the experimental groups, during the designated time period (at the time of extraction, 1 week before extraction, 3 week before extraction and 5 week before extraction) till 1 week after extraction, rats were subcutaneously injected with Alendronate at the dose of 1.0 mg/Kg three times a week. Each specimen from 6 week experimental group and control group were used for microarray analysis, and other specimens were used for histological analysis. The rate of new bone formation within the extraction site and bone loss activity was analyzed using TRAP staining. Statistical analysis was performed using Kruskal Wallis test. (alpha=.05) RESULTS: After one week from the time of extraction, the rate of new bone formation within extraction site for the control group (16.77% +/- 1.36%) compared to the 4 week experimental group (14.99% +/- 6.26%) was lower. However, no statistically significant difference was found. Increase in the number of inactive lacuna (empty lacuna) and decrease in the number of TRAP positive cell were identified with increased duration of administration. There was no significant difference. CONCLUSION: The results of this study showed as the duration of Alendronate administration increased the rate of new bone formation decreased with loss of bone activity and reduced number of osteoclast.

Full mouth rehabilitation of mandibular edentulous patient using implant hybrid prosthesis / 대한치과보철학회지

Implant prosthodontics is beneficial for edentulous patients in enhancing the support, retention, stability, phonation and so on. Various types of prosthesis supported by implant, including implant retained- or supported-overdenture for the removable type and ceramo-metal and fixed prostheses with processed acrylic teeth for the fixed type, are frequently used. Treatment planning for the prosthesis with implant must be made after considering individual characteristics such as form of residual ridge, soft tissue, interocclusal relationship, economic status. Fixed prosthesis with processed acrylic teeth (also known as 'implant hybrid prosthesis' or 'bone anchored bridge') has the advantages of both removable and fixed prosthesis such as proper soft tissue profile, esthetic outcome, increased masticatory efficiency and psychological stability. The 73-years-old female patient came to the department of prosthodontics, Dental hospital of Yonsei University. She was diagnosed with Kennedy class I partial edentulism in the maxilla and complete edentulism in the mandible. This article reports a satisfactory clinical and esthetic outcome of full mouth rehabilitation using removable partial denture in the maxilla and implant hybrid prosthesis in the mandible.

Effect of alendronate on bone remodeling around implant in the rat

PURPOSE: The purpose of this study was to evaluate the effect of alendronates on bone remodeling around titanium implant in the maxilla of rats. MATERIALS AND METHODS: The maxillary first molars were extracted and customized-titanium implants were placed immediately in thirty male Sprague-Dawley rats. The rats were divided into experimental (bisphosphonate) group and control group. At 4 weeks after implantation, the rats in the bisphosphonate group were subcutaneously injected with alendronate three times a week for 6 weeks where as the rats in control group were injected with saline. The rats were sacrificed at 1, 2, 3, 4, or 6 weeks after starting of injection and maxillary bones were collected subsequently. Alveolar bone remodeling around the implants were evaluated by radiographic and histologic analysis. Microarray analysis and immunohistomorphologic analysis were also performed on one rat, sacrificed at 6 weeks after starting of injection, from each group. Statistical analysis was performed using repeated measures analysis of variance and independent t test at a significance level of 5%. RESULTS: There was no statistically significant difference in the bone area (%) around implant between the bisphosphonate group and the control group. However, the amount of empty lacuna was significantly increased in the bisphosphonate group, especially in the rats sacrificed at 4 weeks after starting of injection compared to that of the corresponding control group. The bisphosphonate group showed the same level of TRAP positive cell count, osteocalcin and angiopoietin 1 as the control group. CONCLUSION: Alendronate may not decrease the amount of osteoclast. However, the significantly increased amount of empty lacuna in the bisphosphonate group may explain the suppression of bone remodeling in the bisphosphonate group.