摘要:

SummaryWith increasing emphasis being placed on precision in the construction of prostheses the importance of the visco‐elastic characteristics of tooth support should be understood. Since the tooth returns to its resting position quite slowly, especially when repeated or sustained forces have been applied, an impression prepared prior to full recovery will convey erroneous relationships of the tooth with its neighbours to the working model and, eventually, to the prosthesis.Such an error has been identified in young human subjects when inter‐dental wedges, gingival retraction cord, and rubber dam are placed. The preparation of conventional alginate impressions in special trays can displace abutment teeth to a clinically significant degree as was recorded for seven partially dentate patients. Simple precautions will circumvent these potential sources of er

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01324.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryUsing a representative sample of 5028 dentulous Finnish adults the occurrence of periodontal pockets was studied separately for the maxillae and the mandibles among removable partial denture (RPD) wearers and non‐wearers. RPD(s) were worn in 11.2% of the 3444 maxillae with at least four natural teeth remaining, and in 7.7% of the 4706 corresponding mandibles (P<0.001). Periodontal pockets were more frequently observed in maxillae than mandibles. Wearing of RPDs highly significantly (P<0.0001) increased the odds of having periodontal pockets in general (4 mm or more) as well as the odds of having deeper periodontal pockets (exceeding 6 mm). This phenomenon was observed both in the maxillae and in the mandibles. These results suggest that wearing of RPD is a threat to periodontal tissues and that dentists should take care to frequently recall their patients fitted with RPD(s). During the recall visits more attention should be paid to the periodontal conditions of patients wearing RPD(s

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01325.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe electromyographical silent period in the masseter and the anterior temporalis muscles during tooth tapping and jaw jerk were studied in patients with fairly mild temporomandibular joint dysfunction symptoms. The length of the silent periods in the patient group did not differ generally from that in a control group. During tooth tapping, however, patients with distinct muscular disorders had shorter silent period duration (7.7 ms) than patients with other symptoms or when compared with control subjects (10.5 and 11.3 ms, respectively). The duration returned to normal after correction of the muscular disorders. This finding suggests that the duration of the silent period is affected by the muscle condition. Patients with obvious muscular disorders of mild to moderate magnitude, thus, may show a shorter silent period duration during tooth tapping.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01326.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA comparison of tooth positions and soft tissue profiles was made between samples of edentulous patients recently provided with new complete dentures, and dentate subjects. The dentures were marked with lead foil on the most prominent incisor teeth and labial surfaces of the flanges. Lateral skull radiographs were made with the jaws in centric relation. The dentate subjects were recorded with the teeth held in centric occlusion. Discrete soft and hard tissue landmarks were identified and recorded using an interactive on‐line computer system, enabling linear and angular measurements to be made. A mathematical comparison was produced employing a series of independent t‐tests. Composite computer tracings were also produced. Important differences were found between the two groups, in which the influence of the upper lip length, mandibular resorption, and selected overbite were identified as factors determining artificial tooth posit

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01327.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryElectromyograms (EMGs) of the temporal and masseter muscles in sixty patients with temporomandibular joint disturbance syndrome (TMJDS) and thirty controls were recorded and integrated on‐line in the postural position and during maximum clenching, before and after occlusal splint therapy. Contrasting with the controls, the myoelectrical activity of the patients was higher in the postural position and lower during maximum clenching, whilst the former in percentage terms increased when compared to the latter. After treatment, the EMG indexes in some patients returned partially, and in others completely, to a normal level. Tenderness in the mandibular elevators, deviated opening and organic change in the TMJ increased the postural myoelectrical activity, in percentage terms, against that of maximum clenching. The myoelectrical activity of the mandibular elevators in the postural position and during maximum clenching was smaller in patients with the occlusal splint than in those without. The results show that the mandibular elevators in the patients with TMJDS were hyperactive and tense, and that the occlusal splint was useful for treating such dysfunctio

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01328.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryMaxillary full‐arch splints in the retruded position (RP) and in a right lateral occlusion (1.0‐ 1.5 mm to the right of the retruded contact position) were fabricated for ten subjects. Surface electromyography of the masseter and anterior temporal muscles was performed during submaximal clenching in order to investigate the immediate effects of the splints on the activity patterns of these muscles relative to the patterns found with the subjects occlusion in the inter‐cuspal position. The splints in the RP were found to have no effect on the asymmetry of the activity of the masseter and the anterior temporal muscles, while the splints in a right lateral occlusion resulted in relative increases in right anterior temporal muscle activity (P<0

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01329.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryTen healthy subjects continuously wore equilibrated maxillary full‐arch stabilization splints in the retruded position for 7 days. The muscular activity balance of the masseter muscles during submaximal isometric clenching at 10% and 50% of the maximum voluntary contraction (MVC) did not change immediately on insertion of the splint, but was improved at the 50% level after 7 days (P<0.05). While the muscular balance of the anterior temporal muscles was not affected, either immediately on splint insertion, or after wearing it for 7 days, temporal muscle activity at 10% of the MVC was greater on the side to which the mandible moved from the retruded contact position (RCP) to the inter‐cuspal position (ICP), both before (P<0.025) and after (P<0.01) wearing the splint. Splint removal after 7 days resulted in increased awareness of interferences in the ICP and increases in masseter muscle asymmetry (10%, P<0.025; 50%, P<0.05) when the electromyograms in the ICP after splint removal were compared with those on the stabilization splint before removal. After wearing the splint, the masseter muscle activity at the 10% level was greater on the side where premature contacts were present in the RCP (P<0.01).The use of masticatory muscle asymmetry indices in the evaluation of splint treatment for craniomandibular dysfunction is indicated since submaximal masticatory muscle activity is related to occlusal stability, premature contacts in the RCP and the direction of lateral slides from the RCP to the

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01330.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryTo elucidate the effects of food character on chewing patterns in humans, the electromyographic activity (EMG) of the chewing muscles and also the jaw movements were recorded in twenty‐nine young subjects during ordinary chewing of five different foods.The results obtained were as follows. (a) The harder food materials showed a higher amplitude of the masseter EMG than the softer ones. (b) Concerning the number of chewing strokes and the elapse of time until the last swallowing action, subjects could be divided into two groups. (i) In the first major group, the number of chewing strokes and chewing time until the last swallowing action increased following increase of hardness of the food. This suggests that chewing force and chewing movements may be strongly influenced by the texture of food, especially its hardness. Further, the degree of pulverization of eating materials appears to be the major factor in controlling the swallowing action. (ii) In the second minor group, the chewing strokes and the chewing time were less influenced by the hardness of food. Here, a certain number of chewing strokes could be stimulating the swallowing centre in the brain and so induce swallowing, regardless of the degree of pulverization of the foo

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01331.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA cone‐plate viscometer was employed for studying the rheological characteristics of certain unfilled resins and etching gels. Of these, BIS‐GMA monomer and its diluted mixtures exhibited Newtonian, dilatant and thixotropic behaviour depending on the shear rate. Other unfilled resins also exhibited various types of behaviour. At high shear rates reproducible hysteresis loops were obtained for etching gels which may be useful in characterizat

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01332.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA longitudinal electromyographic (EMG) investigation was performed on thirty subjects provided with an immediate complete upper and a partial lower denture. Electromyographic recordings in maximal clench, light tapping and postural position were obtained from the anterior temporal and masseter muscles before final extractions and 7 weeks, 6 months, 1 year and 2 years after denture insertion.The maximal clench activity of the jaw closing muscles showed an average tendency to decrease upon insertion of the dentures, but thereafter significant increases in mean voltages were observed during the first year of denture wear. During the second year no significant changes in EMG clenching force were noted. At the 2‐year stage most of the muscles showed significantly greater clench activity than at the post‐insertion stage, but did not exceed the pre‐extraction level.The jaw muscle activity in light tapping showed no significant mean changes during the observation period. The postural activity tended to decrease during the period of denture wear, the decrease being significant for some of the muscles at the 2‐yea

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1989.tb01333.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY