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Biomedical subjects

Hai-lan Feng

Publications and source records attributed to Hai-lan Feng.

14 recordsLinked to original sources
PubMed2006

Influence of different post core materials on the color of Empress 2 full ceramic crowns.

BACKGROUND: For esthetic consideration, dentin color post core materials were normally used for all-ceramic crown restorations. However, in some cases, clinicians have to consider combining a full ceramic crown with a metal post core. Therefore, this experiment was conducted to test the esthetical possibility of applying cast metal post core in a full ceramic crown restoration. METHODS: The color of full ceramic crowns on gold and Nickel-Chrome post cores was compared with the color of the same crowns on tooth colored post cores. Different try-in pastes were used to imitate the influence of a composite cementation on the color of different restorative combinations. The majority of patients could not detect any color difference less than DeltaE 1.8 between the two ceramic samples. So, DeltaE 1.8 was taken as the objective evaluative criterion for the evaluation of color matching and patients' satisfaction. RESULTS: When the Empress 2 crown was combined with the gold alloy post core, the color of the resulting material was similar to that of a glass fiber reinforced resin post core (DeltaE = 0.3). The gold alloy post core and the try-in paste did not show a perceptible color change in the full ceramic crowns, which indicated that the color of the crowns might not be susceptible to change between lab and clinic as well as during the process of composite cementation. Without an opaque covering the Ni-Cr post core would cause an unacceptable color effect on the crown (DeltaE = 2.0), but with opaque covering, the color effect became more clinically satisfactory (DeltaE = 1.8). CONCLUSIONS: It may be possible to apply a gold alloy post core in the Empress 2 full ceramic crown restoration when necessary. If a non-extractible Ni-Cr post core exists in the root canal, it might be possible to restore the tooth with an Empress 2 crown after covering the labial surface of the core with one layer of opaque resin cement.

Ceramics↗
PubMed2006

[Biocompatibility test of polymethylmethacrylate denture base resin containing silver-supported antimicrobial agent STR-1 at nanometer level].

OBJECTIVE: To evaluate the biocompatibility of polymethylmethacrylate(PMMA) denture base resin containing silver-supported antimicrobial agent STR-1 of nanometer level in vitro. METHODS: According to the national standards for biological evaluation of dental materials, the cytotoxicity of denture base resin containing STR-1 at concentrations of 5 g/L and 10 g/L was examined by molecular filtrating method, and the hemolysis of STR-1, denture base resin containing STR-1 at concentrations of 5 g/L and 10 g/L was also surveyed. RESULTS: The control denture base resin without containing STR-1 and the denture base resins containing STR-1 at concentrations of 5 g/L and 10 g/L were not cytotoxic to L929 cells. Two hours and 24 hours after cell culturing, the filter membranes of the control and experimental groups were stained evenly with blue color. The staining intensity was not decreased and the fading areas were 0 mm2 during the culturing. The cytotoxicity grades were 0. The hemolysis rates of the antimicrobial agent STR-1 and the denture base resins containing STR-1 at concentrations of 5 g/L and 10 g/L were 1.7%, 3.5% and 3.7% respectively. They were less than the national guild standard 5% which represent no hemolysis. CONCLUSION: The PMMA denture base resins containing silver-supported antimicrobial agents STR-1 of nanometer level at concentrations of 5 g/L and 10 g/L exhibit good biocompatibility.

Animals↗
PubMed2006

[Micro-tensile bond strength to sclerotic dentin in non-carious cervical lesions].

OBJECTIVE: This in vitro study was to evaluate the micro-tensile bond strength (microTBS) of three adhesives to sclerotic dentin in non-carious cervical lesions. METHODS: The maxillary premolars extracted due to periodontitis and with non-carious cervical lesions were collected. The non-carious, natural cervical sclerotic lesions were bonded with a total-etching adhesive Scotchbond Multi-Purpose, a two-step self-etching adhesive Contax, and an all-in-one self-etching adhesive Adper Prompt L-Pop. Artificially prepared wedge-shaped lesions were also made in sound premolars and bonded with the same adhesives as the controls. MicroTBS of these three adhesives was measured. RESULTS: MicroTBS of Scotchbond and Contax to sclerotic dentin was significantly lower than to normal dentin. But microTBS of Adper Prompt L-Pop to normal dentin was significantly lower than to sclerotic dentin. MicroTBS to sclerotic dentin was Scotchbond 46.805 MPa, Adper Prompt L-Pop 39.045 MPa, and Contax 29.852 MPa. CONCLUSIONS: In sclerotic dentin the microTBS was decreased because of the inferior micro-morphology of resin tags. Adhesives with low pH value might bond to sclerotic dentin effectively.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2005

[The biochemical changes of hippocampus in patients before and after denture restoration: a preliminary 1H-magnetic resonance spectroscopy study].

OBJECTIVE: To study the effects of reconstruction of lost occlusal support on the biochemical changes of nervous system. METHODS: The changes of central nervous system metabolic compounds within hippocampus body were measured with proton magnetic resonance spectroscopy ((1)HMRS) before and after denture restoration (six weeks) in seven patients with prolonged loss of occlusal support. RESULTS: (1)HMRS indicated that Cho/Cr decreased by 11.9% (P < 0.05) six weeks after denture restoration, MI/Cr decreased by 28.8% (P < 0.05), and NAA/CR increased by 4.8% (P > 0.05) within hippocampus body. CONCLUSIONS: Recovery of occlusal support facilitates improvement of neuron functions in patients' hippocampus, which may help improve the functions of nervous system.

Aged↗
PubMed2005

[Ultrastructural study of a self-etching adhesive to sclerotic dentin in non-carious cervical lesions].

OBJECTIVE: To examine, in vitro study, the ultrastructure of resin-infiltrated sclerotic dentine following the application of a two-step self-etching dentin adhesive. METHODS: Non-carious, natural cervical sclerotic lesions were bonded using Contax (DMG Hamburg, Germany), a self-etching dentin adhesive. Artificially prepared wedge-shaped lesions were also made in sound bicuspids and bonded using the same adhesive as controls. By SEM examination, the morphological change of the dentin surface treated by Contax Primer, and the hybrid layer and resin tag in the dentin-resin interface were studied. RESULTS: Most dentinal tubules were occluded by rod-like sclerotic casts in the sclerotic dentin surface. Both hybrid layer and resin tag were observed in sclerotic dentin. The hybrid layer was almost similar to that in the sound dentin, but the resin tags were shorter than those in controls. CONCLUSIONS: Bonding to sclerotic dentin is different from sound dentin and may be compromised by occluded dentin tubules. Based on the present ultrastructural features of hybrid layer and resin tags, the Contax, a self-etching dentin adhesive with a low pH value primer, may have some bonding efficacy to sclerotic dentin.

Dentin↗
PubMed2005

[The preliminary study of three-dimensional simulation of the craniofacial system].

OBJECTIVE: To look for the way of three-dimensional simulation of the craniofacial system. METHODS: A three-dimensional laser scanner was used for gypsum models digitization and computed tomography scans was employed for skull reconstruction, then the data of teeth and temporomandibular joint were picked up and integrated. The ARCUS sigma system was used to record spatial mandibular movements. The data of both digital reconstruction and spatial movements were transferred into one coordinate system. The software for three-dimensional simulation was programmed. RESULTS: The preliminary program could be used to analyze static and dynamic occlusion and gnathic relations, to check the contact points and to show from various visual angles and slices. The occlusal plane, curves, and helical axis were initially defined and displayed. CONCLUSIONS: Using available instruments and methods, we developed the primary edition for three-dimensional simulation of the craniofacial system. However, it is far from a mature system and there is still plenty of work to be done.

Dental Occlusion↗
PubMed2005

[Gene mutation detection in a cleidocranial dysplasia family].

OBJECTIVE: To study gene mutation in Chinese patients with cleidocranial dysplasia. METHODS: A three generation family with the clinical diagnosis of cleidocranial dysplasia was investigated in present study. Genomic DNA was extracted from peripheral blood samples of each of the family members. Direct sequencing of the PCR products of the coding region of CBFA1 gene was used to identify the mutations. RESULTS: In each patient of the family, a heterozygous missense mutation, cDNA 674 G > A (R225Q), was detected in CBFA1 exon 3. The mutation changed the sequence in runt domain of the protein. CONCLUSIONS: Our findings indicate that mutation in CBFA1 is responsible for the tooth agenesis and other phenotypes of cleidocranial dysplasia in this Chinese family. The mutation detection could be applied in prenatal diagnosis for the family.

Adolescent↗
PubMed2005

[A survey of number and morphology anomalies in permanent teeth of 6 453 youths between 17 to 21 years old].

OBJECTIVE: To investigate the status of number and morphology anomalies in the permanent teeth. METHODS: A survey of anomalies of number and morphology in the permanent teeth was carried out in 6 453 students who were 17 to 21 years old in 3 colleges during 2002 to 2004. Chi-square test was used to analyze the sex distribution, the involved tooth types and the associated anomalies. RESULTS: The overall prevalence of dental number and morphology anomalies was 16.07%. The prevalence rates of peg-shape (conical) tooth, dens evaginatus and hypodontia were higher in females compared to males (P < 0.05). Dens evaginatus and peg-shape teeth often involved maxillary lateral incisors, Dens evaginatus often involved mandibular second premolars. Fused teeth and hypodontia often involved mandibular incisors. The prevalence of hypodontia coincident with peg-shaped teeth was higher than other associated anomalies (P < 0.01). CONCLUSIONS: The result was similar to other investigations, but peg-shape teeth and dens evaginatus were more prevalent in females than in males.

Adolescent↗
PubMed2004

[Ultrastructural study of sclerotic dentin in non-carious cervical lesions disposed by a total-etching dentin adhesive].

OBJECTIVE: To examine the ultrastructure of resin-infiltrated sclerotic dentine following the application of a three-step total-etching dentin adhesive. METHODS: Naturally-occurring, non-carious cervical lesions on extracted premolars were bonded using a total-etching dentin adhesive-Scotchbond Multi-purpose. Artificially prepared wedge-shaped lesions were also made in sound premolars and restored using the same adhesive as control. The morphological change of the dentin surface conditioned with the etchant, and the hybrid zone and resin tags in the dentin-resin interface were studied by SEM. RESULTS: Most dentinal tubules were obliterated by rod-like sclerotic casts in the non-carious cervical lesion, and could not be dissolved by Scotchbond Multi-purpose etchant. Both the hybrid zone and resin tags were observed in sclerotic dentin after restoration, although the resin tags were fewer and in lack of communications, the length of resin tags and the thickness of the hybrid zone were almost similar to those of the sound dentin. CONCLUSION: Bonding to sclerotic dentin is different from sound dentin, and may be compromised by the fewer resin tags and communications.

Acid Etching, Dental↗
PubMed2004

[Microcosmic analysis of TCP/HA coating with micro-pores on titanium by IBAD method.].

PURPOSE: In order to improve the biocompatibility of dental implants, the physical structure and the chemical composites of tricalcium phosphate/hydroxyapatite(TCP/HA) coating on titanium were studied. METHODS: Coatings of TCP/HA and hydroxyapatite (HA) on titanium were formed by ion beam assisted deposition (IBAD) method. The scanning electron microscope (SEM) and atomic force microscope (AFM) were used to study the morphology of the coating surfaces. The chemical components and structure of the modified surfaces were characterized using energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). RESULTS: The results showed that there were many micro-pores in the TCP/HA coating by SEM and AFM. The chemical components analysis showed that the Ca/P ratio of TCP/HA coating was lower than that of HA coating. The XRD showed that the TCP/HA coating was composed of TCP and HA. CONCLUSION: The results indicated that the TCP/HA coating with micro-pores was formed on titanium by IBAD method successfully. With higher binding strength between TCP/HA and titanium, this coating will be a potential coating material for dental implant, especially for the biological seal at the cervical level of the implant.

Calcium Phosphates↗
PubMed2003

[The study of natural head posture in edentulous patients before and after oral rehabilitation].

OBJECTIVE: To study the natural head posture (NHP) of edentulous patients compared with dentate people and to understand NHP shift immediately inserting complete dentures and three months after denture wearing. METHODS: The NHPs of twenty edentulous patients and twenty-two dentate subjects were recorded with cephalometric technique. The NTPs of edentulous patients were exposed three times, before inserting, right after inserting and three months after inserting dentures. The NHPs of dentate subjects were recorded once as a controlled group. Six angles measured from the radiographs were evaluated for the NHP and three angles and two linear measures for the mandibular position. RESULTS: Compared with dentate subjects, the craniomandibular angles of the edentulous patients increased and the camber of the cervical columns decreased, but changes of the NHP were not significant. The mandible showed a significant upward moving (P < 0.05) and an insignificant forward moving. At the time of denture insertion, the camber of the cervical columns significantly increased (P < 0.05). Three months after using the dentures, the craniomandibular angles of the patients obviously decreased. (P < 0.05). CONCLUSION: The shift of NHP after denture inserting does exist. The shifted NHP of the patients with dentures is a new balanced posture and closer to the normal position than the NHP of them without dentures.

Adult↗
PubMed2003

[A comparative study of masticatory efficiency and mandibular movement pattern among patients with CD, COD and IOD].

OBJECTIVE: To compare the masticatory efficiency and the character of mandibular movement trace of the patients with complete denture (CD), complete overdenture (COD) and implant-supported overdenture (IOD). METHODS: A total of 42 subjects were rehabilitated with CD, COD and IOD respectively and wore the dentures at least half a year. Each study group was composed of 14 subjects. The masticatory function of patients were investigated by means of masticatory efficiency and mandibular movement trace. The characters of mandibular movement trace were evaluated from four aspects: the regulation of chewing cycle, centralization of end traces, the type of the contact slides and the type of the trace on the frontal plane. RESULTS: The average chewing efficiency of almond and jujube in the IOD patients was higher than that in the CD group (P < 0.01), and the chewing efficiency of almond in COD group was higher than that in the CD group (P < 0.01). In the IOD group, there were more patients with regular chewing cycle (P < 0.05) and centralized end traces (P < 0.01) in mandibular movement than those in the CD group and COD group. CONCLUSIONS: IOD and COD benefit the fully or partially edentulous patients with a relatively good masticatory function. The patients with IOD have more regular mandibular movement than those with CD.

Adult↗
PubMed2003

[Cases analysis and clinical classification of oligodontia].

OBJECTIVE: To classify the clinical symptoms of oligodontia and summarize the characteristics of the diseases. METHODS: 33 patients with congenitally permanent teeth missing (6 or more than 6) were taken clinical examination, diagnosis, prosthetic treatment and made records of the status of tooth agenesis, systemic symptoms, and family history. RESULTS: The symptoms of oligodontia were clinically classified into two groups: oligodontia with or without systemic syndromes. And the former has two typical kinds of diseases: anhidrotic/hypohidrotic ectodermal dysplasia (EDA) and Rieger syndrome. CONCLUSIONS: Correct diagnosis and early treatment for these patients are of very importance.

Adolescent↗