Health behaviors and tooth retention among older adults in China: findings from the 4th Chinese national oral health survey.

BACKGROUND: This study aimed to examine the association between oral health behaviors and tooth retention among Chinese older adults. METHODS: Data were used from the 4th Chinese National Oral Health Survey, a nationally representative sample. The sample included 9054 older adults aged 55 to 74. Control variables and oral health behaviors were measured through a questionnaire interview, and the number of remaining teeth and periodontal health were obtained from an oral health examination. A chi-square test was used for univariate analysis. Multivariate Logistic regression was used to explore the association between health behaviors and the number of remaining teeth. RESULTS: The average number of remaining teeth in the sample was 24.4 ± 7.7. There was a higher proportion of older adults living in urban areas with 20 or more teeth than those living in rural areas (83.2% vs. 79.4%, P < 0.001); and a higher proportion of individuals with high education levels with 20 or more teeth compared to those with low education levels (P < 0.001). Logistic regression models showed that older adults who used toothpicks `(OR = 3.37, 95% CI 2.94-3.85), dental floss (OR = 1.93, 95% CI 1.05-3.53), toothpaste (OR = 3.89, 95% CI 3.14-4.83); and never smoked (OR = 1.43 95% CI 1.20-1.70) were more likely to retain 20 or more natural teeth; whereas older adults who had a dental visit were less likely to retain 20 or more natural teeth (OR = 0.45, 95% CI 0.39-052). CONCLUSION: Good oral hygiene practices, never smoking, and regular dental visits focusing on prevention are significantly associated with teeth retention. It is critical to promote a healthy lifestyle and improve prevention-oriented oral health care systems.

Diet and lifestyle habits associated with caries in deciduous teeth among 3- to 5-year-old preschool children in Jiangxi province, China.

BACKGROUND: The purpose of this study was to investigate the status of caries in deciduous teeth and the effect of diet and lifestyle habits on dental caries among 3- to 5-year-old preschool children in Jiangxi Province, China. METHODS: In total, 2880 cases involving preschool children were selected by stratified cluster sampling. The dental examination methods and criteria followed the WHO guidelines. SPSS 19.0 was used for the statistical analysis. Chi square tests were used to compare the caries prevalence among children with different social characteristics. Non-parametric tests were used to compare the decayed, missing and filled teeth (dmft) index values. Univariate and multivariate regression analyses were used to study the effect of diet and lifestyle habits on dental caries. RESULTS: The caries prevalence among the 2880 cases of 3- to 5-year-old preschool children in Jiangxi Province, China was 49.13%. There was no gender difference in this rate (P > 0.05). The caries prevalence increased with age (P < 0.05). The prevalence of caries in the rural areas was higher than that in the urban areas (P < 0.05). The deciduous central incisors and deciduous molars had a higher caries prevalence than the other deciduous teeth. According to the multivariate logistic regression analysis, the caries risk increased with living in a rural area, exclusive breastfeeding, greater frequency of daily snacking, high frequency of snacking before sleep and beginning to brush teeth at a late age; the caries risk decreased when parents helped their children brush their teeth. CONCLUSION: The caries prevalence among 3- to 5-year-old preschool children in Jiangxi was lower than the level throughout the country and lower than the rate in other developing countries. The children's diet and lifestyle habits were closely related to dental caries. Parents and children should be more aware of oral health, and parents should help their children develop healthy lifestyle behaviours.

[Effect of different cleaning methods on bond strength and surface wettability of high translucency zirconia].

PURPOSE: To study the effect of different cleaning methods on the shear bond strength of self-adhesive resin cement to saliva-contaminated high translucency zirconia and surface wettability. METHODS: Eighty zirconia specimens were randomly divided into 5 groups (n=16), i.e., control group(not contaminated), 75% ethanol group,cleaning paste group,airborne-particle abrasion group, and atmospheric pressure cold plasma group. The contact angles was measured, shear bond strength were examined, and fracture types were determined. SPSS 26.0 software package was used for statistical analysis of the data. RESULTS: The atmospheric pressure cold plasma group produced the lowest contact angle(P＜0.05). The shear bond strength of the airborne-particle abrasion group, the cleaning paste group and the atmospheric pressure cold plasma group respectively were similar to the control group without significant difference(P＞0.05), while those were significantly higher than 75% ethanol group(P＜0.05). The mixed fracture mode of the atmospheric pressure cold plasma group evidently increased. CONCLUSIONS: Airborne-particle abrasion, cleaning paste and atmospheric pressure cold plasma overcome the effects of saliva contamination, producing the shear bond strength to zirconia similar to the control group. The atmospheric pressure cold plasma improves hydrophilicity of high translucency zirconia significantly.

Hypofibrinogenemia is an independent predictor of hemophagocytic lymphohistiocytosis in children with sepsis.

Hemophagocytic lymphohistiocytosis (HLH) is a potentially life-threatening condition in children with sepsis. We herein aimed to identify clinical and laboratory predictors of HLH in children with sepsis. We conducted a retrospective study of 568 children with sepsis admitted to Guangdong Women and Children Hospital from January 2019 to June 2022. HLH, while rare (6.34%), proved to be a highly fatal complication (37.14%) in children with sepsis. Children with HLH had higher levels of aspartate aminotransferase, lactate dehydrogenase, triglycerides, and ferritin than children without HLH; conversely, they displayed decreased levels of neutrophils, hemoglobin, platelets, fibrinogen, and albumin. Additionally, the HLH group showed higher rates of prolonged fever (> 10 days), hepatomegaly, and splenomegaly than the non-HLH group. Our retrospective analysis identified hypofibrinogenemia (OR = 0.440, P = 0.024) as an independent predictor for the development of HLH in patients with sepsis. The optimal cutoff value for fibrinogen was found to be < 2.43 g/L. The area under the curve for diagnosing HLH was 0.80 (95% confidence interval: 0.73-0.87, P < 0.0001), with a sensitivity of 72.41% and specificity of 76.27%. Thus, hypofibrinogenemia emerges as a potentially valuable predictor for HLH in children with sepsis.

Achieving a tunable and ultra-broadband near-infrared emission in the Ga2-2xZnxGexO3:Cr3+ phosphor.

Near-infrared (NIR) spectroscopy (700-1100 nm) based on a phosphor-converted light-emitting diode (pc-LED) has multi-functional applications in bio-imaging, night-vision, and food quality analysis, simulating the development of efficient and ultra-broadband NIR phosphors. Herein, a series of tunable and ultra-broadband NIR phosphor Ga2-2xZnxGexO3:Cr3+ was successfully produced by a [Zn2+-Ge4+] unit co-substituting a [Ga3+-Ga3+] unit in Ga2O3:Cr3+. With the increasing amount of [Zn2+-Ge4+] incorporation, the emission peak can be tuned from 726 to 808 nm, and the maximum FWHM can be extended from 126 to 190 nm. However, the excitation peak position remained nearly unchanged in the blue light region, enabling this material to perfectly match the InGaN blue LED chip. Although the gradually enhanced electron-lattice coupling and low energy barrier for thermal quenching caused by this co-substitution lead to a decrease in the photoluminescence quantum yield (PLQY) and thermal stability, respectively, the absolute values of these two criteria can be well maintained. Finally, to evaluate the practical applications, prototype NIR pc-LEDs were fabricated using these materials combined with 450 nm LED chips. Under the same conditions, the NIR output power and photoelectronic conversion efficiency of these devices are superior to those fabricated using the well-known ScBO3:Cr3+ phosphor. These results demonstrate that this series of materials with tunable and ultra-broadband NIR emissions has great potential for NIR pc-LED applications.

Producing Tunable Broadband Near-Infrared Emission through Co-Substitution in (Ga1-xMgx)(Ga1-xGex)O3:Cr3.

Broadband near-infrared (NIR) phosphors are in high demand for creating "smart" NIR phosphor-converted light-emitting diode (pc-LED) sources. In this work, a series of Cr3+-substituted NIR-emitting materials with highly efficient, broad, tunable emission spectra are achieved by modifying the simple oxide Ga2O3 using [Mg2+-Ge4+] and [Ga3+-Ga3+] co-unit substitution. The results show that the emission peak can be shifted from 726 to 830 nm while maintaining a constant excitation peak in the blue light region, enabling extensive application. The optical properties stem from changes in the Cr3+ crystal field environment upon substitution. Intriguingly, the temperature-dependent photoluminescence emission peak position shows virtually no change in the [Mg2+-Ge4+] co-substituted materials. This abnormal phenomenon is found to be a comprehensive embodiment of a weakening crystal field environment (red-shift) as the temperature increases and reduced local structure distortion (blue-shift) with increasing temperature. The high quantum yield, NIR emission, and net-zero emission shift as a function of temperature make this phosphor class optimal for device incorporation. As a result, their performance was studied by coating the phosphor on a 450 nm emitting LED chip. The fabricated device demonstrates an excellent NIR output power and NIR photoelectric conversion efficiency. This study provides a series of efficient, tunable, broadband NIR materials for spectroscopy applications and contributes to the basic foundation of Cr3+-activated NIR phosphors.

Analysis of gum bleeding among children aged 12-15 years in Jiangxi Province and related influencing factors.

OBJECTIVE: To study the prevalence of gum bleeding in children aged 12-15 years in Jiangxi Province and related influencing factors for the development of effective prevention and treatment strategies. METHODS: A multistage cluster stratified sampling method was used to select 8,160 children aged 12-15 years for this study. Enrolled children completed a set of survey questionnaires covering children's gender, age, parents' educational level, oral health knowledge scores, attitude scores, and brushing habits in addition of dental examination. All the data were analyzed using the chi-square test and logistic regression. RESULTS: Among 8,160 children, the gum bleeding rate was 66.5 percent (95% CI: 65.8%-68.1%). The gum bleeding rate in urban children (68.0 percent) was higher than that in rural areas (65.0 percent) (P < 0.01); the gum bleeding rate in boys (67.6 percent) was higher than that in girls (65.4 percent) (P < 0.05). The results of binary logistic regression analysis showed that age, urban and rural areas, mother education, knowledge score, attitude score, and brushing frequency were all important factors affecting gum bleeding. CONCLUSION: This study showed that incidence of gum bleeding in Jiangxi children is high which is affected by their age, mother's education, and several other factors. These new findings form the baseline information essential for the development of more effective approaches to prevent and control children gum bleeding in Jiangxi and other regions in the future.

Dental caries and associated factors among adolescents aged 12 to 15 in Jiangxi Province, China.

BACKGROUND: The purpose of this survey was to examine the association of general characteristics, oral health knowledge, attitudes, behavior, and dental caries status among adolescents in Jiangxi Province and to provide a basis for future prevention of dental caries among middle school students. METHODS: A total of 8,160 adolescents aged 12 to 15 years were invited to participate in this survey by a stratified random cluster sampling method from 30 schools in five counties in Jiangxi Province. A self-administered questionnaire was used to understand their basic characteristics, including oral health behaviors, knowledge, and attitudes. Chi-square tests were used to compare dental caries status and general characteristics. Univariate and multivariate logistic regression analyses were used to study the effects of oral health knowledge, attitudes, and behavior on dental caries. RESULTS: The prevalence of dental caries in permanent teeth was 25.8 percent, and the mean DMFT score of 12- to 15-year-old adolescents was 0.48 ± 1.04. The prevalence in rural areas was higher than that in urban areas (P < 0.001). The prevalence was higher in girls than in boys (P < 0.001). No significant age differences were observed (P > 0.05) in the prevalence of dental caries. The multivariate logistic regression analysis indicated that the variables associated with dental caries were tooth brushing frequency, use of toothpaste, frequency of sugary milk intake, smoking, and oral health attitudes. CONCLUSIONS: This study revealed that adolescent oral health behaviors and attitudes were associated with dental caries. It is important to implement targeted oral disease prevention and control measures among adolescents.

[Prevalence of malocclusion among 5 387 12- to 14-year-old adolescents in Jiangxi province, China: an epidemiological study].

OBJECTIVE: We provided baseline data for oral public health through epidemiological surveys to investigate the prevalence of malocclusion and orthodontic treatment proportion in 12- to 14-year-old adolescents in Jiangxi province, China. METHODS: Multi-stage random cluster sampling was used. A total of 5 387 12- to 14-year-old adolescents were examined by three professional dentists according to Angle's classification of malocclusion. The subjects were recruited from 30 secondary schools in five counties in Jiangxi Province. Results were statistically analyzed by SPSS19.0. RESULTS: The prevalence of malocclusion was 79.67% among adolescents aged 12-14 years in Jiangxi province. The composition ratios of ClassⅠ, Class Ⅱ Division 1, Class Ⅱ Division 2, and Class Ⅲ malocclusion were 30.96%, 16.36%, 12.78%, and 19.13% respectively. ClassⅠmalocclusion had the highest composition ratio, and the most common clinical manifestation of malocclusion was dentition crowding with a prevalence of 91.30%. The prevalence rate of malocclusion was higher in boys than in girls at 81.16% and 78.21%, respectively (P<0.05). This condition had different prevalence rates in Nanchang, Yichun, Jiujiang, Shangrao, and Ganzhou (P<0.05) with the highest in Nanchang and lowest in Ganzhou. Malocclusion was related to caries, and its prevalence rate was higher in patients with caries than in those without caries (P<0.05). The orthodontic rate of malocclusion was 2.63%, and the value was higher for girls than that for boys (P<0.05). The rate of orthodontic in urban areas was higher than that in rural areas (P<0.05). CONCLUSIONS: Compared with local and international findings on malocclusion of adolescents, high prevalence and low orthodontic rate were found in Jiangxi province. Strengthening the combination of prevention and treatment is important for the physical and mental health of adolescents. We should actively conduct oral health education, popularize the knowledge of malocclusion, and actively treat caries.

[Status and strategies of oral health service demand and medical treatment utilization among 3- to 5-year-old preschool children in Jiangxi province].

OBJECTIVE: This study aimed to investigate the oral health service needs and dental treatment among 3-year-old to 5-year-old preschool children in Jiangxi province and provide data to support the development of relevant oral health policies, enhance the oral health service utilization and visit rate, and optimize oral manpower and service resources. METHODS: A total of 2 880 preschool children were selected via stratified cluster sampling. Dental examination methods and criteria according to the fourth national oral health epidemiological survey were adopted. Excel 2007 and SPSS 19.0 softwares were used for statistics analysis. Chi-square test and logistic regression analysis were performed. RESULTS: The caries prevalence was 49.13% (1 415/2 880) among the 2 880 cases of 3-
year-old to 5-year-old preschool children in Jiangxi province, approximately 53.37% (1 537/2 880) of which possessed oral health service needs. The parents of younger children assessed the oral situation better in older age than in their younger years (P<0.05), which was better in urban children than in rural children (P<0.05). The visiting rate of all the respondents was 12.33% (355/2 880), while the visiting rate of children with oral diseases was 17.31% (266/1 537). The top three reasons why patients did not visit the dentist were as follows: children's teeth have no problem, the teeth damage in teeth was considerably minimal, and primary teeth would be replaced without the need for treatment. The influencing factors included lower visiting rate in females than in males (OR=0.499, 95%CI: 0.411-0.606) and lower visiting rates in rural areas than in urban areas (OR=0.428, 95%CI: 0.353-0.519). Subjects with poor oral health and high oral knowledge scores possessed high dental service visit rates. CONCLUSIONS: The prevalence of caries in 3-year-old to 5-year-old preschool children in Jiangxi province is at a lower level than that in the national level. The proportion of the population actively seeking medical services is low, and their main purpose of treatment is to treat rather than prevention. Oral health education should be strengthened, and it should be incorporated to the contents of the kindergarten teacher training program to improve residents' awareness regarding children's oral health.

[Effect of different dentin cleaning agents on the bond strength of self-adhesive resin cement to dentin].

OBJECTIVE: This study aims to evaluate the bond strength of a self-adhesive resin cement to dentin by ethylene diamine tetraacetic acid (EDTA) and NaClO. METHODS: Twenty-seven freshly extracted non-carious human premolars were prepared to expose the buccal dentin and randomly divided into three groups: control group (A group), EDTA group (B group) and NaClO group (C group). All teeth were bonded to dentin using a self-adhesive resin cement after the teeth in the A group were processed with distilled water. The B and C group were processed with 3%EDTA and 1%NaClO, respectively. After 24 hours at 37 °C water, the shear bond strengths of the twenty-four specimens were measured. All statistical analysis was performed using SPSS 17.0 software package. Each fractured specimen was examined under dental microscope. Three new specimens were cut, and the morphologies of the cement-dentin interface were observed under scanning electron microscope (SEM). RESULTS: The shear bond strength in the A group, B group and C group was (8.55±0.63), (8.47±0.56) and (12.97± 0.59) MPa, respectively. The difference between A group and B group was no statistically significant (P>0.05), whereas the difference between C group and B group (or A group) was statistically significant (P<0.05). SEM observation of the cement-dentin interface in the C group showed good adaptation, but resin tags were not observed. The other two groups showed poor bonding interface. Most of the fractured adhesive dentin surfaces exhibited cohesive failure in the A group and B group. All the fractured adhesive dentin surfaces exhibited cohesive failure in the C group. CONCLUSION: 1% NaClO can increase the bond strength of self-adhesive resin cement to dentin, but 3%EDTA has no effect.

[Study on the effect of different impression methods on the marginal fit of all-ceramic crowns].

OBJECTIVE: To investigate the effect of three different impression methods on the marginal fit of all-ceramic crowns. The three methods include scanning silicone rubber impression, cast models, and direct optical impression. METHODS: The polymethyl methacrylate (PMMA) material of a mandibular first molar in standard model was prepared with 16 models duplicated. The all-ceramic crowns were prepared using three different impression methods. Accurate impressions were made using silicone rubber, and the cast models were obtained. The PMMA models, silicone rubber impressions, and cast models were scanned, and digital models of three groups were obtained to produce 48 zirconia all-ceramic crowns with computer aided design/computer aided manufacture. The marginal fit of these groups was measured by silicone rubber gap impression. Statistical analysis was performed with SPSS 17.0 software. RESULTS: The marginal fit of direct optical impression groups, silicone rubber impression groups, cast model groups was (69.18±9.47), (81.04±10.88), (84.42±9.96) µm. A significant difference was observed in the marginal fit of the direct optical impression groups and the other groups (P<0.05). No statistically significant difference was observed in the marginal fit of the silicone rubber impression groups and the cast model groups (P>0.05). CONCLUSION: All marginal measurement sites are clinically acceptable by the three different impression scanning methods. The silicone rubber impression scanning method can be used for all-ceramic restorations.

Minimally invasive restoration of endodontically treated teeth / 口腔疾病防治

@#The aims of tooth restoration of endodontically treated teeth are to protect the remaining dental tissue; restore coronal morphology, functions and aesthetics; prevent bacterial microleakage and ensure periodontal healthy; prevent fracture of the restorations and reduce the wear from antagonist teeth. This article reviews the preservation and minimally invasive restoration of endodontically treated teeth. The results of the literature review show that tooth fracture resistance decreases after root canal treatment, the amount of remaining tooth tissue is an important factor affecting the success of root canal treatment, and the neck is the stress concentration area of tooth tissue, the traditional full crown and postcore crown have a certain amount of abrasion on the healthy neck teeth tissue, which will further reduce the bending resistance of the teeth and may cause the teeth to fracture. With the development of bonding technology, composite resin materials and ceramic materials, there are fewer molar tissues removed when resin, inlay, onlay, overlay and inlay crown are used to repair tooth defects, which can better preserve the remaining tooth tissues, especially the neck tooth tissues. After root canal treatment, only the pulp cavity of the tooth can be directly repaired by resin. When the marginal ridge is absent, minimally invasive restoration methods, such as inlay, onlay, and inlay crown, can be selected according to the number of marginal ridges removed and the thickness of the remaining dental tissue.

[Assessment of occlusal vertical dimension using angles: a pilot study].

OBJECTIVE: This study aims to identify highly accurate quantitative methods for evaluating the occlusal vertical dimension by using cephalometric radiographs to analyze the craniofacial hard tissue landmarks in 30 cases with normal occlusions. METHODS: A total of 30 subjects with normal occlusions and aged between 20 and 30 years old were included in the study. Cephalometric radiographs were obtained and analyzed using the Winceph 8.0 measurement software. Landmark points were identified and measured. RESULTS: The mean distribution difference of the center angle (CA) and lower angle (LA) of the face was not statistically significant (t = -1.490, P = 0.147). The CA and LA had a significantly linear correlation (r = 0.976, P = 0.000), and the regression equation was y = 0.298 + 0.997x. CONCLUSION: The CA can be used to assess and quantify the occlusal vertical dimension in clinical practice.

[Clinical evaluation of denture adhesive combined with oral wetting spray on satisfaction of complete denture in xerostomia patients].

PURPOSE: The purpose of this study is to investigate the effect of denture adhesive and oral wetting spray on the satisfaction of wearing complete denture in xerostomia patients. METHODS: Ten edentulous patients who suffered from deficient residual alveolar ridge and xerostomia with poor retention and stability of complete dentures or mandibular complete dentures were employed to assess the differences of satisfaction after use of denture adhesive in their dry oral cavity for 1 week, and use of denture adhesive combined with oral wetting spray for 1 month, 3 months and 6 months by using satisfaction questionnaire. The statistical analysis was carried out with SPSS17.0 software package. RESULTS: Six months after the use of denture adhesive combined with oral wetting spray, the satisfaction of complete denture was significantly improved in respects of general satisfaction, retention of mandible denture, comfort and mastication improvement than that before application (P<0.05). But 1 week after the use of denture adhesive alone, the satisfaction of comfort reduced than that before application (P<0.05). CONCLUSIONS: Denture adhesive combined with oral wetting spray can be used to improve the satisfaction of xerostomia patients treated with complete denture who suffered from deficient residual alveolar ridge.

[In vitro study on shear bond strength of veneering ceramics to zirconia].

OBJECTIVE: To investigate the shear bond strength between veneering ceramic and zirconia core in different all-ceramic systems. METHODS: Twenty disk-shaped specimens with 8 mm in diameter and 3 mm in height for each zirconia system (Lava, Cercon, IPS e.max ZirCAD, Procera) were fabricated respectively and divided into four groups: Lava group, Cercon group, IPS e.max ZirCAD group, Procera group. For each group, 10 specimens were sintered with 1 mm corresponding veneering ceramic, while the other were sintered with 2 mm corresponding veneering ceramic respectively. The shear bond strength and fracture mode of specimens were observed and determined. RESULTS: The values of shear bond strength for Lava, Cercon, IPS e.max ZirCAD and Procera were (13.82 +/- 3.71), (13.24 +/- 2.09), (6.37 +/- 4.15), (5.19 +/- 5.31) MPa in the group of 1 mm thicked veneering ceramics, respectively, while the values in the group of 2mm thicked veneering ceramics were (38.77 +/- 1.69), (21.67 +/- 3.34), (12.70 +/- 4.24), (9.94 +/- 6.67) MPa. The values of Lava and Cercon groups were significantly higher than that of IPS e.max ZirCAD and Procera groups (P < 0.05). And the values of 2 mm thicked veneering ceramic group were significantly higher than that in 1 mm thicked groups (P < 0.05). Adhesive fracture between core and veneering ceramics were observed in the fracture modes of most specimens. CONCLUSION: The shear bond strength of veneering ceramic to the zirconia framework are different from the zirconia system we chose, and the thickness of veneering ceramic has a great impact on its shear bond strength.

[Clinical evaluation of indirect post core by two different impression methods].

OBJECTIVE: To evaluate the clinical effect of indirect cast post core by two different impression methods between silicone rubber impression and agar/alginate combination impression. METHODS: 389 massive destruction teeth after root canal therapy were randomly divided into two groups (group A and group B). The teeth of group A was treated by silicone rubber impression material for making indirect post core impression. The teeth of group B was treated by agar/alginate combination impression for making indirect post core impression. The effect of two different impression methods was evaluated. RESULTS: The success rate of making indirect post core impression by silicone rubber impression method was higher than that of making impression by agar/alginate combination impression method. Significant difference was found in making indirect post core impression between premolars and molars by two different impression methods (P<0.05), while there was no significant difference in making indirect post core impression of anterior teeth by two different impression methods (P>0.05). CONCLUSION: The clinical effect of making indirect post core impression by silicone rubber impression method is better than that of making impression by agar/alginate combination impression method.

[In vitro comparison of the retention adjustment of telescopic crowns].

PURPOSE: The objective of the present in vitro study is to explore the retention readjustment measure of the non-precious metal telescopic crown. METHODS: Twenty-seven standard size dies were divided into three groups randomly, conventional Co-Cr alloy group, Co-Cr alloy slit telescopic crown group and Au-Pd alloy group. Each group had 9 dies. The retentive force of telescopic crowns was investigated after repeated insertion/separation tests. Statistical analysis was performed using SPSS12.0 software package for one-way ANOVA. RESULTS: The retention of Au-Pd crown group and Co-Cr alloy slit telescopic crown was significantly larger than that of conventional Co-Cr alloy crown group. The maximal retention of Co-Cr alloy slit of the telescopic crown group was significantly larger than Au-Pd crown group. Compared with Co-Cr alloy slit telescopic crown group, the retention of all procedures in Au-Pd crown group had statistical significance except the retention of 800 procedures. CONCLUSIONS: The retention of slit telescopic crown is similar to precious mental telescopic crown. Slit telescopic crown can compensate the retention deficient of none-precious metal telescopic crown. Supported by Science and Technology Research Project of Bureau of Health of Jiangxi Province (Grant No.060436).