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Biomedical subjects

S H Wei

Publications and source records attributed to S H Wei.

At least 37 records · Page 2Linked to original sources
PubMed1999

The influence of rehabilitation therapy on the prognosis for stroke patients--a preliminary study.

The purpose of this prospective study was to investigate the influence of rehabilitation therapy on the prognosis for stroke patients. Sociodemographic and clinical factors were collected in a sample of 147 stroke patients (81 men and 66 women) admitted to the inpatient rehabilitation department at our university hospital over 10 days between January 1, 1997 and December 31, 1997. Functional Independence Measure (FIM) scores at discharge and gains during rehabilitation period were used as the prognosis index. Statistical techniques with univariate and multiple regression analyses indicated that significant predictors of discharge FIM scores include age, previous attacks twice or over, medical comorbidities, sensory and orientation impairments, and dementia. In addition, previous stroke attacks twice or over and sensory impairment were significant predictors of FIM gains during rehabilitation period. We concluded that: 1) age is a critical factor to determine the rehabilitation outcome, but may not be an important factor to predict the ability for the improvement through rehabilitation therapy; 2) the delay of rehabilitation therapy may not affect the potential for further improvement; 3) patients with low initial functional level may have poor final outcome, they may still have good rehabilitation potential to improve the functional level; 4) complications of stroke may affect the rehabilitation outcome and should be prevented; and 5) patients with impaired mental status should not routinely be excluded from rehabilitation programs.

Adult↗
PubMed1999

Clinical investigation of a high-strength glass ionomer restorative used with the ART technique in Wuhan, China: one-year results.

OBJECTIVE: To evaluate the safety and effectiveness of a new glass ionomer restorative, ChemFlex, and to compare its clinical performance and wear to another popular material, Fuji IX GP, when used with the atraumatic restorative treatment (ART) approach in posterior teeth in school children. METHODS: Ninety-two subjects aged between 6 and 14 years who had bilateral matched pairs of carious posterior teeth were selected. A split-mouth experimental design was used in which the two restorative materials were randomly placed on contralateral sides. The restorations were assessed directly and also indirectly from color transparencies and die replicas. RESULTS: After one year, the success rates of ART restorations in the primary teeth were 96.6% for ChemFlex restorations and 89.7% for Fuji IX GP restorations placed in the Class I cavity preparations, whereas only 46.2% (ChemFlex) and 61.5% (Fuji IX GP) of Class II restorations were assessed as clinically satisfactory. In the permanent dentition, the success rates were 94.6% and 98.2% for ChemFlex and Fuji IX GP, respectively; however, there was no statistically significant difference between the two restoratives for either the permanent or primary teeth. The mean occlusal wear after one year in the permanent teeth was 53.2 microns for ChemFlex and 56.3 microns for Fuji IX GP. Again, there were no statistically significant differences in wear between the two materials (P > 0.05). CONCLUSION: The clinical performance of both ChemFlex and Fuji IX GP over a 12-month period was highly satisfactory and completely adequate for the ART technique, particularly in Class I cavities.

Adolescent↗
PubMed1998

Micromorphological spectrum of acid-conditioned dentin following the application of a water-based adhesive.

OBJECTIVES: The goal of this study was to illustrate the micromorphological spectrum along the resin-dentin interface when a water-based, dentin adhesive (Scotchbond Multi-purpose) was applied to acid-conditioned dentin under different dry and wet bonding conditions. METHODS: Twenty-eight 1 mm dentin discs were each conditioned with 10% maleic acid for 15 s. Twenty-four of these discs were randomly divided into four groups, based upon the status of the remaining surface moisture: Group I (30 s dry); Group II (3 s dry); Group III (visibly moist) and Group IV (overwet). They were bonded using Scotchbond Multi-purpose. The remaining four discs were bonded using an experimental water-based primer containing 35 vol.% HEMA (Group V). Laminated dentin disc pairs were prepared for transmission electron microscopic examination. RESULTS: In all groups, diffusion of the polyalkenoic acid copolymer component of the primer into acid-conditioned dentin was localized to the surface region of the hybrid layer. The remaining part of the hybrid layer (the subsurface region) appeared variable. In Group I (30 s dry), collagen fibrils were collapsed. In Group II (3 s dry) and Group III (visibly moist), stained collagen fibrils were surrounded by wide electron-lucent interfibrillar spaces. In Group IV (overwet), a marked diffusion gradient was observed representing dilution of part of the primer components. In addition, an electron-dense primer phase, containing electron-lucent globular domains was invariably observed, irrespective of the hydration status of the demineralized collagen matrix. This electron dense phase was absent when HEMA alone was used as the primer (Group V). SIGNIFICANCE: With the use of a water-based adhesive, one could briefly air-dry the acid-conditioned dentin and allow the water in the primer to rehydrate the collapsed collagen matrix, without the risk of incomplete hybridization or tubular seal along the resin-dentin interface. However, care should be exercised to minimize dilution of the water-soluble primer component.

Acid Etching, Dental↗
PubMed1998

Relation between water content in acetone/alcohol-based primer and interfacial ultrastructure.

OBJECTIVES: This study investigated the ultrastructure of the resin-dentine interface when a two-bottle primer system containing NTG-GMA (N(p-tolyl)glycine-glycidyl methacrylate) and BPDM (biphenyl dimethacrylate) was used with different concentrations of water as a part of the primer solvent: (I) an experimental version of All-Bond 2 with no water in primer A; (II) a commercial version of All-Bond 2 (Bisco, Itasca, IL, USA) with 5% water in primer A; and (III) a former version of All-Bond 2 with 17% water in primer A. METHODS: Thirty-six 1-mm thick dentine discs prepared from third permanent molar teeth were each conditioned with 10% phosphoric acid for 20 s and rinsed for 20 s. They were randomly divided into three groups: Group A, conditioned dentine surface air-dried for 30 s; Group B, air-dried for 3 s; and Group C, blot-dried so that the dentine surface remained visibly moist. The three categories of primers were applied to each disc in 8-10 coats, resulting in nine sub-groups. Discs in each sub-group were bonded together to form disc-pairs using a chemical cure resin, demineralized in ethylene diamine tetraacetic acid (EDTA) and prepared for transmission electron microscopic examination. RESULTS: With the use of the water-free primer version, sub-optimal hybridization was observed whenever dentine was dried prior to bonding (Groups IA and IB). In the 5% water version, prolonged desiccation resulted in compromised hybridization (Group IIA), while resin globules were observed on the surface of the hybrid layer when a moist technique was employed (Group IIC). In the 17% water version, surface blisters and globules characteristic of the 'overwet phenomenon' were observed in Groups IIIB and IIIC. CONCLUSION: Between the two extremes of a morphological spectrum of bonding conditions, the different primer versions exhibited different sensitivity ranges. There was a shift in the 'window of opportunity' for optimal hybridization and tubular seal depending on the water content of the primer system investigated.

Acetone↗
PubMed1998

Cephalometric and occlusal changes following maxillary expansion and protraction.

A prospective clinical trial was conducted to determine the cephalometric and occlusal changes following maxillary expansion and protraction. Twenty Southern Chinese patients (eight males and 12 females with a mean age of 8.4 +/- 1.8 years) with skeletal Class III malocclusions were treated consecutively with maxillary expansion and a protraction facemask. Growth adaptation of these patients was followed for 2 years after removal of the appliances and compared with a control group of subjects with no treatment. Lateral cephalometric radiographs were used to quantify the skeletal and dental changes before treatment (T1), immediately after treatment (T2) and 2 years after removal of appliances (T3). With 8 months of treatment (T2-T1), overjet was overcorrected from a -2.0 to 3.5 mm. The maxilla moved forwards by an average of 2.1 mm and the molar relationship was improved to a Class I dental arch relationship. The palatal and occlusal planes were tilted upward 1.0 and 2.0 degrees, respectively. Two years following removal of the appliances (T3-T2), a positive overjet was maintained in 18 out of 20 patients. The maxilla continued to move forwards in the treated subjects similar to the controls. The mandible outgrew the maxilia. In most instances, dental compensation with proclination of the maxillary incisors was observed. The palatal plane returned to pre-treatment value. The occlusal plane continued to tilt upward due to eruption of the molars and proclination of the incisors. Analysis of dental casts showed a significant increase in maxillary intercanine (2.2 mm) and intermolar widths (2.3 mm) with 7 days of rapid palatal expansion followed by maxillary protraction. The percentage relapse in maxillary intermolar widths was 30-45 per cent after 1 year, in most cases with minimal retention. In the mandibular arch, the concurrent increase in intermolar width (2.3 mm) was primarily due to buccal uprighting of the posterior molars when the maxilla was protracted into a Class I skeletal relationship and was stable after 1 year. The results of this study indicate stability of orthopaedic treatment of Class III malocclusions directed at the maxilla. Despite some relapse, a net improvement in maxillomandibular relationship and a positive overjet was maintained in 18 out of 20 patients at the end of the follow-up period.

Cephalometry↗
PubMed1998

Microsurgical management of intracranial epidermoid cysts.

BACKGROUND: Intracranial epidermoid cysts are slow-growing congenital neoplasms that usually spread and adhere to critical neurovascular structures along the basal cistern, particularly the cerebellopontine angle (CPA) and parasellar region. Clinical symptoms include trigeminal neuralgia, headache and dizziness, progressive hemiparesis, unstable gait and hemifacial spasm. With the aid of modern imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), an effective microsurgical approach can be planned preoperatively to completely remove tumors and avoid complications. METHODS: Twenty-six patients with intracranial epidermoid cysts were microsurgically treated between July 1984 and June 1997. Diagnostic procedures included enhanced CT and/or CT cisternography and MRI. All patients underwent microsurgical treatment for tumor removal. RESULTS: Total tumor removal was achieved in 12 patients (46.2%), near-total removal in seven (26.9%), partial removal in six (23.1%) and stereotactic biopsy in one patient (3.8%). Postoperative deterioration of the neurologic condition was found in three patients who required further surgery, aseptic meningitis in four patients and communicating hydrocephalus requiring shunting in three patients. The functional prognoses were excellent in 23 patients (88.5%), good in two patients (7.7%) and fair in one patient (3.8%). Among the 26 patients, three died of pneumonia three, six and nine months after surgery, respectively. CONCLUSIONS: MRI is particularly useful for defining the anatomic limits of tumor tissue and surgical planning. The surgical results were excellent in patients with near-total tumor removal, as well as in patients with total removal. Aggressive surgical tumor removal may result in transient, but significant, cranial nerve palsy and should be avoided. Perioperative administration of steroids and wound protection may be beneficial for preventing the development of postoperative aseptic meningitis and hydrocephalus.

Adult↗
PubMed1997

Sacroiliac motion for extreme hip positions. A fresh cadaver study.

STUDY DESIGN: This study placed fresh cadavers in different hip positions and obtained sacroiliac kinematics. The magnitudes and directions of angular and linear sacroiliac motion are reported. OBJECTIVES: To determine the three-dimensional motion at the left and right sacroiliac joints and to explore the mechanical structure of the sacroiliac joint. SUMMARY OF BACKGROUND DATA: Previous in vivo and in vitro studies have reported various amounts of motion at the sacroiliac joints, ranging from no motion to 18 degrees. The results of previous studies have typically not been reported as data in classic engineering terms, and three-dimensional analyses are sparse. Importantly, previous studies have not used external hip positions to elucidate the full range of sacroiliac motion. METHODS: Radiopaque markers were placed in the sacrum and each innominate bone before standardized performance of computed tomography scans at 3-mm intervals, with the fresh cadaver stabilized in the side-lying position on a specially constructed pallet. Computed tomography images were stored on magnetic tape, from which coordinates for centroids of the markers were obtained and subsequent mechanical analyses performed. The intersubchondral lines on the images were traced and reconstructed using computer technology to obtain the thickness of the intersubchondral joint space and the general configuration of the sacroiliac joints. RESULTS: The methods used in this study were validated. The largest amount of sacroiliac motion occurred in the sagittal plane (7 degrees on left and 8 degrees on the right, with a range of 3 degrees to 17 degrees). Definite trends in the direction of angular sacroiliac motion occurred with respect to both bilateral and reciprocal hip joint positions. The translation or linear motion of the posterior superior iliac spines with respect to the sacrum ranged from 4 to 8 mm. This motion tended to occur in all directions, with no detectable trends. The average intersubchondral thickness of the sacroiliac joint was 1.2 mm and the shape of the joint resembled that of an airplane propeller. CONCLUSIONS: Even though the subjects in this study were elderly, considerable angular and linear motion was in evidence. As such, it appears that extreme hip positions are necessary to elucidate full range of motion at the sacroiliac joint. The magnitude and direction of demonstrated sacroiliac motion appears to be sufficient to complement hip joint motion and influence motion at the lumbosacral junction and, thus, low back pain in both the direct and indirect sense.

Aged↗
PubMed1997

Altered immune responses in interleukin 10 transgenic mice.

Interleukin (IL)-10 is a pleiotropic cytokine which inhibits a broad array of immune parameters including T helper cell type 1 (Th1) cytokine production, antigen presentation, and antigen-specific T cell proliferation. To understand the consequences of altered expression of IL-10 in immune models of autoimmune disease, the response to infectious agents, and the response to tumors, we developed transgenic mice expressing IL-10 under the control of the IL-2 promoter. Upon in vitro stimulation, spleen cells from unimmunized transgenic mice secrete higher levels of IL-10 and lower amounts of IFN-gamma than do controls, although no gross abnormalities were detected in lymphocyte populations or serum Ig levels. Transfer of normally pathogenic CD4(+) CD45RBhigh splenic T cells from IL-10 transgenic mice did not cause colitis in recipient severe combined immunodeficiency mice. Furthermore, co-transfer of these transgenic cells with CD4(+) CD45RBhigh T cells from control mice prevented disease. Transgenic mice retained their resistance to Leishmania major infection, indicating that their cell-mediated immune responses were not globally suppressed. Lastly, in comparison to controls, IL-10 transgenic mice were unable to limit the growth of immunogenic tumors. Administration of blocking IL-10 mAbs restored in vivo antitumor responses in the transgenic mice. These results demonstrate that a single alteration in the T cell cytokine profile can lead to dramatic changes in immune responses in a manner that is stimulus dependent. These mice will be useful in defining differences in inflammatory conditions and cellular immunity mediated by IL-10.

Animals↗
PubMed1997

The overwet phenomenon in two-component acetone-based primers containing aryl amine and carboxylic acid monomers.

OBJECTIVES: The overwet phenomenon was first reported when a moist bonding technique was used with an earlier commercial version of All-Bond 2 (Bisco) that contained BPDM in primer B. This study investigated whether ultrastructural features of the overwet phenomenon could also be detected in other commercially available two-component acetone-based primers containing BPDM, PMDM and PMGDM, as well as an experimental two-component primer containing DSDM. METHODS: Thirty 1 mm dentin discs prepared from third molars were each conditioned with 10% H3PO4 for 20 s and rinsed for 20 s. They were randomly divided into 5 groups: Group I (Bond-It, Jeneric/Pentron:PMGDM); Group II (Wet Bond, Chameleon Dental Products:PMGDM); Group III (Tenure S, Den-Mat:PMDM); Group IV (present commercial version of All-Bond 2, Bisco:BPDM) and Group V (Experimental two-component primer system containing DSDM in primer B). Following a moist bonding technique using the respective system, discs from each group were further bonded together to form three disc pairs using a chemical-cured resin. Bonded disc pairs were demineralized in EDTA and processed for TEM examination. For this ultramicroscopical study, results such as the features of the overwet phenomenon were analyzed by visual inspection of the specimens in each group (n = 12). RESULTS: Isolated blister-like spaces of variable dimensions were observed within the primer layer in all groups and possessed the following characteristics: 1) a layer of resin-impregnated dentin was always present along the base of the primary blister; 2) surface primer globules, sometimes containing secondary blisters, were identified within these primary blisters; 3) dentinal tubules within the blister-like spaces were not completely sealed; 4) primer globules were circumscribed by a halo of fine kinked strands of material. SIGNIFICANCE: Although the technique of moist bonding is based on valid biological principles, incorporation of resin monomers that are immiscible with water rendered the application of current two-component, acetone-based primers very technique-sensitive in terms of tubular seal, when used on moist, acid-conditioned dentin. Further studies should be directed at elimination of this type of oil-in-water (O/W) "macroemulsion" formation through optimal micellar solubilization of these resin monomers in water.

Acetone↗
PubMed1997

Timing for effective application of anteriorly directed orthopedic force to the maxilla.

Class III malocclusion with retrusive maxilla can be orthopedically corrected in the deciduous and mixed dentition, with reverse-pull headgear in combination with rapid palatal expansion. The literature recommends this procedure be carried out before the patient is 8 years old to obtain the optimal orthopedic result. This statement, however, has not been supported by scientific data. The current study examined the treatment effects of patients younger than 8 years old (5 to 8 years) and patients older than 8 years old (9 to 12 years). Thirty patients treated with maxillary protraction and expansion in the Department of Children's Dentistry and Orthodontics, University of Hong Kong were included in this study. Cephalometric radiographs were taken 6 months before the initiation of treatment (T(0)), at the initiation of treatment (T1), and after 6 months of treatment (T2). In this way, (T(2)-T1) represented cephalometric changes during the treatment period and (T1-T0) represented 6 months of growth changes without treatment. Experimental subjects served as their own control in this study. A grid system consisting of maxillary occlusal plane (OL) and a line perpendicular to OL through sella (OLp) was used for linear measurements. A total of 15 linear and 3 angular cephalometric measurements were made. A multivariate analysis of variance (MANOVA), which used age and treatment time as its factors, was used to determine effect of age and/or treatment on each cephalometric parameter. Results indicated strikingly similar therapeutic response between the younger and older age groups. These data suggest that similar skeletal response can be obtained when maxillary protraction was started either before age 8 (5 to 8 years) or after age 8 years (8 to 12 years).

Aging↗
PubMed1997

Treatment response and long-term dentofacial adaptations to maxillary expansion and protraction.

The purpose of this article is to summarize the short-term and long-term results of the authors' clinical prospective study on the treatment of Class III malocclusion using the protraction facemask. An attempt is made to answer questions pertaining to this treatment modality. Twenty patients with skeletal Class III malocclusion were treated consecutively with maxillary expansion and a protraction facemask. A positive overjet was obtained in all cases after 6 to 9 months of treatment. These changes were contributed to by a forward movement of the maxilla, backward and downward rotation of the mandible, proclination of the maxillary incisors, and retroclination of the mandibular incisors. The molar relationship was overcorrected to Class I or Class II dental arch relationship. The overbite was reduced with a significant increase in lower facial height. The treatment was found to be stable 2 years after removal of the appliances. At the end of the 4-year observation period, 15 of the 20 patients maintained a positive overjet or an end-to-end incisal relationship. Patients who reverted back to a negative overjet were found to have excess horizontal mandibular growth that was not compensated by proclination of the maxillary incisors. A review of the literature showed that maxillary expansion in conjunction with protraction produced greater forward movement of the maxilla. Maxillary protraction with a 30 degrees forward and downward force applied at the canine region produced an acceptable clinical response. The reciprocal force from maxillary protraction transmitted to the temporomandibular joint did not increase masticatory muscle pain or activity. Significant soft tissue profile change can be expected with maxillary protraction including straightening of the facial profile and better lip competence and posture. However, one should anticipate individual variations in treatment response and subsequent growth changes. Treatment with the protraction facemask is most effective in Class III patients with a retrusive maxilla and a hypodivergent growth pattern. Treatment initiated at the time of initial eruption of the upper central incisors helps to maintain the anterior occlusion after treatment.

Adaptation, Physiological↗
PubMed1997

Masticatory muscle pain before, during, and after treatment with orthopedic protraction headgear: a pilot study.

Protraction headgear has been used in conjunction with a palatal expansion appliance to correct Class III malocclusion with maxillary deficiency and/or mandibular prognathism. In general, 800 gm of orthopedic force is used to protract the maxilla, and 75% of this force is transmitted to the temporomandibular joint (TMJ) area via the mandible. The effect of this heavy intermittent force on the TMJ has not been reported in the literature. The objectives of this study were to determine the level of masticatory muscle pain and EMG activity in patients treated with maxillary protraction headgear. Ten patients with skeletal Class III malocclusion whose treatment plan called for maxillary protraction headgear treatment participated in this study. Nocturnal masticatory muscle activity was determined using a portable electromyographic (EMG) recording device. Subjects wore the EMG device 14 nights before treatment, 14 nights during treatment, and 14 nights 1 month after active treatment. Masticatory muscle pain level was determined by muscle palpation, scored on a scale of 0 to 3 each period, according to the method of Gross and Gale. The examiner followed a sequence outlined by Burch to examine the masticatory muscles. Results showed no significant differences for masticatory muscle activities before, during, and after treatment. Only a few patients experienced level 1 masticatory pain during treatment. None of the patients experienced masticatory muscle pain 1 month after treatment. These results demonstrate no significant increase in masticatory muscle activity or muscle pain associated with orthopedic treatment using maxillary protraction headgear.

Adolescent↗
PubMed1997

A 4-year longitudinal study of the oral prevalence of enteric gram-negative rods and yeasts in Chinese children.

A 4-year longitudinal study of the oral prevalence of enteric gram-negative rods and yeasts in 116 Chinese primary school children in Hong Kong was conducted. The oral prevalence of enteric gram-negative rods for each consecutive year was 25.3%, 37.0%, 24.0% and 25.8% respectively, with a weighted mean of 27.9%. Enterobacteriaceae, which comprised 57% of all enteric gram-negative rods, were more common in children with no caries experience. The oral prevalence of yeasts for each consecutive year was 7.7%, 12.0%, 14.4% and 15.5% respectively, with a weighted mean of 12.5%. Candida albicans comprised 84% of all yeasts isolated. Oral yeast carriage was significantly associated with caries prevalence. While the oral prevalence of enteric gram-negative rods in primary school children in Hong Kong may be higher than in other parts of the world, repeated isolation of either enteric gram-negative rods or Candida spp. from individual children over the 4-year study period was rare, suggesting that carriage of these organisms is transient.

Candida↗
PubMed1997

Clinical evaluation of compomer in primary teeth: 1-year results.

The clinical performance of the compomer Dyract (L.D. Caulk, Dentsply) was evaluated and compared with that of the hybrid composite resin Prisma TPH (L.D. Caulk, Dentsply) in restorations of 60 bilateral matched pairs of primary teeth. After 1 year, the overall failure rate for both restorative materials was 1.7 percent. There were no statistically significant differences in recurrence of caries, color matching, marginal integrity or anatomic form. The only statistically significant differences were in marginal discoloration and wear, where the compomer was inferior to the hybrid composite resin. The authors conclude that compomer is a suitable alternative to amalgam for restoring primary teeth.

Case-Control Studies↗
PubMed1997

Cephalometric comparisons of Chinese and Caucasian surgical Class III patients.

Pretreatment cephalometric radiographs of 30 Chinese and 30 Caucasian surgical Class III patients were studied to determine if there were skeletal and soft tissue morphology differences between the groups. Nineteen hard tissue and 13 soft tissue measurements were traced and digitized. A two-sample t test was used to analyze sex and ethnic differences between groups. A significant difference between sexes was found in the linear skeletal measurements but not in the angular measurements for both ethnic groups. Ethnic differences were found in the anterior cranial base measurement, which was significantly shorter in the Chinese sample. In addition, a larger posterior cranial base, a smaller gonial angle, and an increase in mandibular length contributed to the increase in mandibular prognathism found in the Chinese sample. Few differences between sexes were found in the soft tissue measurements. However, ethnic differences were found in maxillary and mandibular soft tissue prognathism, upper and lower lip protrusion, and nasolabial angle, which reflected the more severe underlying skeletal disharmony in the Chinese sample. When the surgical samples were compared to a reference population, an increase in skeletal measurements was found with the Chinese sample in maxillary and mandibular prognathism and dentoalveolar protrusion. Soft tissue maxillary prognathism and upper lip protrusion were found to be smaller than the reference population in the Caucasian sample but greater in the Chinese sample.

Adolescent↗
PubMed1997

Ultrastructure of the resin-dentin interface following reversible and irreversible rewetting.

PURPOSE: This study investigated the effect of reversible and irreversible rewetting on the application of One-Step, single-bottle, water-free, acetone-based primer/adhesive. MATERIALS AND METHODS: Thirty 1 mm dentin discs prepared from third molars were each conditioned with 10% H3PO4 for 20 seconds and rinsed for 20 seconds. They were randomly divided into five groups: Group 1 (positive control): conditioned dentin bonded visibly moist; Group 2: bonded after drying for 3 seconds; Group 3: drying for 3 seconds and rewetting with distilled water; Group 4 (negative control): drying for 3 seconds, stored in 8% glutaraldehyde for 15 minutes, rinsed with distilled water and dried for 3 seconds; and Group 5: drying for 3 seconds, stored in glutaraldehyde for 15 minutes, rinsed with distilled water and bonded visibly moist. One-Step was applied in two coats according to the manufacturer's recommendation and discs in each group were further bonded together to form a disc-pair using a chemical cure resin, demineralized in EDTA and prepared for TEM examination. RESULTS: Complete resin infiltration into the zone of demineralized dentin was observed in Group 1 and 3. In Group 2, resin infiltration was limited to the surface and base of the demineralized network apparently along the lateral branches of the dentin tubules. A middle zone of suboptimal infiltration was observed. In Group 4 and 5, minimal resin infiltration was only observed along the base of the demineralized network upon their fixation in a collapsed state with glutaraldehyde.

Collagen↗
PubMed1997

Chewing gum and saliva in oral health.

The crucial role played by many properties of saliva in preventing dental caries, maintaining the plaque pH and controlling the equilibrium between enamel de- and remineralization has been demonstrated. This has been documented by the effects of salivary dysfunction on caries incidence and by the distribution of sites of caries predilection in areas where saliva presence is restricted. The use of sugar-free chewing gum has been increasingly accepted as one adjunct to oral hygiene procedures. It has become part of an anti-caries prevention program, especially in patients suffering from xerostomia. Chewing gum not only acts as a salivary stimulant but may also be a useful vehicle for some agents such as fluoride, chlorhexidine and calcium phosphate. Moreover, in some countries gum containing nicotine has been used to substitute the nicotine from cigarettes to reduce the effects of nicotine withdrawal reaction from people attempting to stop smoking.

Carbohydrates↗