Effect of occlusal splints for the management of patients with myofascial pain: a randomized, controlled, double-blind study / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Occlusal splints have been the preferred modalities in the management of myofascial temporomandibular disorders (TMDs), but now controversy exists in reporting whether they are successful for TMDs treatments. The aim of this study was to give objective evidence to the assessment of treatment effect of occlusal splints for myofascial TMDs patients by clinical assessments and surface electromyography (sEMG) measurements of masseter muscles (MM).</p><p><b>METHODS</b>Thirty-six patients (12 males and 24 females) aged 16 - 57 (38 ± 11) years participated in the study. All participants diagnosed with myofascial TMD were randomized into two groups (18 of each). Patients in the first group (A) were treated with occlusal splints for 1 month, while patients in the second group (B) were treated with placebo (non-occluding palatal) splints. Clinical assessments were performed at the beginning of the study and 1 month after treatment. sEMG measurements for MM were performed at mandibular postural position (MPP) and maximum intercuspal contacted position (ICP) 1 month after the treatment. The root mean square (RMS) and the median frequency (MF) as linear indices of sEMG data were used to demonstrate muscle activity and muscle fatigue. Data were analyzed by ANOVA and post hoc SNK test. The differences were considered significant at P < 0.05.</p><p><b>RESULTS</b>It was found that 89% of group A either completely recovered (39%) or clinically improved (50%), while only 22% of group B had a spontaneous improvement. sEMG analysis showed that at MPP, the mean of RMS value of MM in group A was lower than that of group B, which shows statistical differences (P < 0.01). At ICP, the RMS value of MM in group A was higher than that of group B, which shows statistical differences (P < 0.01). At MPP, MF value of MM in group A was higher than that of group B (P < 0.05). At ICP, MF value of MM was lower than that of group B (P < 0.01).</p><p><b>CONCLUSIONS</b>Occlusal splint could eliminate or improve the signs and symptoms of TMD patients with myofascial pain. sEMG analysis indicates that the wearing of occlusal splints may reduce the degree of fatigue of the masticatory muscles. The splint therapy outcome has a correlation with the electromyographic changes in the masticatory muscles.</p>

Colonization of Tannerella forsythus and Prevotella intermedia in dental plaque samples from children of Changchun Ziqiang primary school / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To detect the presence of Tannerella forsythus (Tf) and Prevotella intermedia (Pi) using polymerase chain reaction (PCR) in the oral plaque samples from children and investigate the relationship between bacteria and clinical parameters.</p><p><b>METHODS</b>A total of 151 children aged 7 to 12 years were selected from Changchun primary school. The supragingival plaque sample was collected from the mesiobuccal and labial surfaces of the right maxillary central incisor (FDI1) and the right maxillary first molar (FDI6). Extracted DNA from plaque samples was used for PCR analysis. Intraoral examination, probing depth (PD) and bleeding on probing (BOP) were performed and recorded.</p><p><b>RESULTS</b>The detection rate for Tf was 40.3% (118/293) and Pi was 46.4% (136/293) in supragingival plaque. The detection rates for Tf and Pi in molars were much higher than those in incisors (P < 0.01). The detection rate of Tf and Pi was positively related to BOP+ and PD. The detection rate for Pi decreased gradually with age, and the detection rate for Tf was highest in the group aged 7 to 8 and the detection rates for Tf and Pi were higher in the gingiva with BOP+ than that with BOP- (P > 0.05). The detection rates for Tf increased remarkably with BOP+ and especially when PD was greater than 4 mm.</p><p><b>CONCLUSIONS</b>Detection rates of putative periodontal pathogens from healthy children of 7 to 12 years of age were high. The detection rates for Tf and Pi in molars were much higher than those in incisors, and the presence of Tf and Pi in supragingival plaque was related to periodontal parameters.</p>

Receptor activator of nuclear factor kappa B ligand and osteoprotegerin expression in chronic apical periodontitis: possible association with inflammatory cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL) and osteoprotegerin (OPG) have been recently shown to play important roles in bone resorption. The aim of this study was to investigate the possible association between the expression of bone resorption regulators (RANKL and OPG) and inflammatory cell infiltration in chronic apical periodontitis.</p><p><b>METHODS</b>The samples of chronic periapical lesions (n = 40) and healthy periapical tissues (n = 10) were examined for immunohistochemical analysis of RANKL and OPG. Lesion samples were further analyzed for the inflammatory infiltration condition. The inflammatory cell infiltration was scored in relation to immunohistochemical reactivity for CD3, CD20 and CD68.</p><p><b>RESULTS</b>The number of RANKL-positive cells and the ratio of RANKL/OPG in chronic apical periodontitis were significantly higher than those in healthy periapical tissues (P < 0.001). The number of RANKL-positive cells was higher in lesions with severe inflammatory infiltration than in those with light inflammatory infiltration (P < 0.05). Significantly increased RANKL expression was found with T lymphocytes (CD3(+)), macrophages (CD68(+)) and B lymphocytes (CD20(+)) infiltration (P < 0.05). No association was found between the ratio of RANKL/OPG and inflammatory cell infiltration.</p><p><b>CONCLUSIONS</b>RANKL expression was increased with T, B lymphocytes and macrophages infiltration, respectively in chronic periapical lesions. RANKL appears to be closely related to periapical inflammatory infiltrates. The relative ratio of RANKL/OPG may be a key determinant of RANKL-mediated bone resorption.</p>

Distribution of periodontal pathogens in dental plaque samples from 7 to 12-years-old children of Changchun Ziqiang primary school / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To detect the presence of Porphyromonas gingivalis (Pg) and Actinobacillus actinomycetemcomitans (Aa) using polymerase chain reaction (PCR) in the oral plaque samples from children and investigate the relationship between bacteria and clinical parameters.</p><p><b>METHODS</b>A total of 151 children aged 7 to 12 years were selected from Changchun Ziqiang primary school. The supragingival plaque sample was collected from the mesiobuccal and labial surfaces of the right maxillary central incisor and the right maxillary first molar. Extracted DNA from plaque samples was used for PCR analysis. Intraoral examination, probing depth (PD) and bleeding on probing (BOP) were performed and recorded.</p><p><b>RESULTS</b>The detection rate for Pg was 27.6% and Aa 54.3% in supragingival plaque. The detection rates for Pg in molars were much higher than those in incisors (P < 0.01). The detection rate of Pg was positively related to BOP+ and PD. The detection rate for Pg increased gradually with aging, and the detection rate for Aa was highest in the group aged 11 to 12 and the detection rates for Pg and Aa were higher in the gingiva with BOP+ than that with BOP- (P < 0.05). The detection rates for Pg increased remarkably with BOP+ and especially when PD was greater than 4 mm.</p><p><b>CONCLUSIONS</b>Detection rates of putative periodontal pathogens from healthy children of 7 to 12 years of age were high. The detection rates for Pg in molars were much higher than those in incisors,and the presence of Pg and Aa in supragingival plaque was related to periodontal parameters.</p>

Bond strength of different adhesives to normal and caries-affected dentins / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Currently, several systems of dentin substrate-reacting adhesives are available for use in the restorative treatment against caries. However, the bond effectiveness and property of different adhesive systems to caries-affected dentin are not fully understood. The objective of this study was to evaluate the bond strength of different adhesives to both normal dentin (ND) and caries-affected dentin (CAD) and to analyze the dentin/adhesive interfacial characteristics.</p><p><b>METHODS</b>Twenty eight extracted human molars with coronal medium carious lesions were randomly assigned to four groups according to adhesives used. ND and CAD were bonded with etch-and-rinse adhesive Adper Single Bond 2 (SB2) or self-etching adhesives Clearfil SE Bond (CSE), Clearfil S(3) Bond (CS3), iBond GI (IB). Rectangular sticks of resin-dentin bonded interfaces 0.9 mm(2) were obtained. The specimens were subjected to microtensile bond strength (microTBS) testing at a crosshead speed of 1 mm/min. Mean microTBS was statistically analyzed with analysis of variance (ANOVA) and Student-Newman-Keuls tests. Interfacial morphologies were analyzed by Scanning Electron Microscopy (SEM).</p><p><b>RESULTS</b>Etch-and-rinse adhesive Adper(TM) Single Bond 2 yielded high bond strength when applied to both normal and caries-affected dentin. The two-step self-etching adhesive Clearfil SE Bond generated the highest bond strength to ND among all adhesives tested but a significantly reduced strength when applied to CAD. For the one-step self-etching adhesives, Clearfil S(3) Bond and iBond GI, the bond strength was relatively low regardless of the dentin type. SEM interfacial analysis revealed that hybrid layers were thicker with poorer resin tag formation and less resin-filled lateral branches in the CAD than in the ND for all the adhesives tested.</p><p><b>CONCLUSION</b>The etch-and-rinse adhesive performed more effectively to caries-affected dentin than the self-etching adhesives.</p>

Stress area of the mandibular alveolar mucosa under complete denture with linear occlusion at lateral excursion / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The rocking and instability of a loaded complete denture (CD) during lateral excursion reduce the bearing area under the denture base, causing localized high stress concentrations. This can lead to mucosal tenderness, ulceration, and alveolar bone resorption, and the linear occlusion design was to decrease the lateral force exerted on the denture and to ensure denture stability. But it is not known how the bearing areas of linear occlusal CDs (LOCDs) and anatomic occlusal CDs (AOCDs) differ. The purpose of this study was to analyze and compare the distributions of the high and low vertical stress-bearing areas in the mandibular alveolar mucosa under LOCDs and AOCDs at lateral excursion.</p><p><b>METHODS</b>Computerized tomography (CT) and finite element analysis were used to establish three-dimensional models of an edentulous maxilla and mandible with severe residual ridge resorption. These models were composed of maxillary and mandibular bone structure, mucosa, and the LOCD or AOCD. Lateral excursion movements of the mandible were simulated and the vertical stress-bearing areas in the mucosa under both mandibular CDs were analyzed using ANSYS 7.0.</p><p><b>RESULTS</b>On the working side, the high stress-bearing (-0.07 to -0.1 MPa) area under the LOCD during lateral excursion was smaller than that under the AOCD, while the medium stress-bearing (-0.03 to -0.07 MPa) area under the LOCD was 1.33-fold that under the AOCD. The medium stress-bearing area on the non-working side under the LOCD was 2.4-fold that under the AOCD. Therefore, the overall medium vertical stress-bearing area under the LOCD was 20% larger than that under the AOCD.</p><p><b>CONCLUSIONS</b>During lateral excursion, the medium vertical stress-bearing area under a mandibular LOCD was larger and the high vertical stress-bearing area was smaller than that under an AOCD. Thus, the vertical stress under the LOCD was distributed more evenly and over a wider area than that under the AOCD, thereby improving denture stability.</p>

Stress distribution in alveolar bone around implants under implant supported overdenture with linear occlusion at lateral occlusion / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze stress distribution in alveolar bone around implants of implant supported overdentures (ISO) with linear occlusion and with anatomic occlusion at lateral mandibular position, and to justify the possibility of decreased injurious force around implants in ISO with linear occlusion.</p><p><b>METHODS</b>Computerized tomography scan and finite element analysis (FEA) were used to set up two 3-D FEA models of maxillae and mandible with severe residual ridge resorption. The mucosa, linear and anatomic occlusal ISO with bar attachments, and two implants inserted between mandibular foramina were also established in the models. With the condition of imitating the loading of masseter muscles, these models were loaded to simulate the stress distributions in alveolar bone around implants under ISO at lateral occlusion position.</p><p><b>RESULTS</b>At lateral occlusion, the stress distributions in alveolar bone around implants under ISO with anatomic occlusion were mainly on the lingual and distal sides of the working side implants. However, stress distributions under ISO with linear occlusion were on the distal sides of bilateral implants. Both the stress peaks of ISOs with linear occlusion and with the anatomic one appeared in the working side. In anatomic occlusion model, sigma(z): -6.47 MPa and 6.81 MPa, sigma(1): -4.20 MPa and 7.20 MPa (negative value: compressive stress, positive value: tensile stress); in linear occlusion model, sigma(z): -4.86 MPa and 3.04 MPa, sigma(1): -3.48 MPa and 5.33 MPa.</p><p><b>CONCLUSIONS</b>At lateral occlusion, when comparing the ISO with two different occlusion schemes, stress peak in alveolar bone around implants in the linear occlusion model was lower than that in the anatomic occlusion model at equal loading situation. Stress in the alveolar bone under ISO with linear occlusion distributed more evenly than that under ISO with anatomic occlusion.</p>

Primary clinical application of linear occlusion in immediate loading and implant-supported mandibular overdenture / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate clinical feasibility and technical features of immediate loading with linear occlusion on 2-implant-supported overdenture and to evaluate short-term effect of the treatment</p><p><b>METHODS</b>Six edentulous patients with severe residual ridge resorption were enrolled. Two interforaminal implants were inserted for each patient and then immediate impressions were taken. Implant-supported bar-retained overdentures were restored for the patients within 24 hours. Clinical and radiographic examinations were conducted post-operative 1 week and 1, 3, 6, and 12 months. Thereafter at every 6 months the stability of implants, tissue situations around implants, radiographs and satisfaction level of patients were examined for each patient.</p><p><b>RESULTS</b>Six cases and 12 implants were followed from 9 to 30 months. No implant was loosened or dropped. Sulculus bleeding index was 0-1 and probing depth of sulcus was less than 2 mm. The gingival tissues around the implants were healthy. Radiographic examination showed that bone resorption was less than 1 mm in the first year. The alveolar bone around the implants hasn't show obvious resorption stable height. Patients were satisfied with the implants.</p><p><b>CONCLUSIONS</b>The results of this study indicate that immediate loading using linear occlusion on implant-supported bar-retained overdenture is predictable in some cases and can achieve satisfaction in the short-term service. Further study is needed to assess the long-term results.</p>