• Journal of Periodontal and Implant Science
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• v.23 no.2
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• pp.352-357
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• 1993

The purpose of the present study was to evaluate and compare the periodontal conditions of distally extending cantilever bridges(CB) and removable patial dentures(RPD). 78 patients treated with removable partial dentures were divided into 2 groups; bilateral free-ending (type 1) and unilateral free-ending(type 2). 43 patients treated with distally extending cantilever bridges were divided into 4 groups according to position of missing molars and number of including abutment tooth (or teeth) (type 1-4). Prosthodontic status of the abutment teeth were assessed; overcontoured crown, overhanged margin, embrasure closure, and others. Their Periodonted status were assessed with Plaque Index Gingial Index(GI) Sulcus bleedy Index (SBI), Tooth mobility(TM) & Posher depth(PPD). 35.9% of RPD group and 38.1 of CB grouphad disconfort on mastication with prosthetics. 16.7% of RPD group and 6.1% of CB group showed on opposing sites. Overhanged margins were 58.3% for RPD group and 86.6% for GB group. 45.5% of RPD group and 72% of CB group had embrasure closure on the abutment teeth. 30.5% of GB group had oversized pontic. Gb group showed much higher clinical parameters than RPD groups, but statistically not significant. Type 2 of RPD group showed lower GI and SBI, but statistically not significant. Type 3 of CB group showed the highest GI and SBI and type 2 showed the highest tooth mobility, but there is no differences between the same type of groups. In conclusion, only minor differences in periodontal conditions were recorded in RPD and CB group.

• Journal of Oral Medicine and Pain
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• v.33 no.1
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• pp.85-95
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• 2008

The purpose of this study was to evaluate the effects of oral habits on the muscles of mastication and facial expression by means of two parameters: muscle stiffness and elasticity. 10 healthy, fully-dentate male subjects in their twenties were selected for this study; all had normal Class I occlusal relationships. Muscle stiffness and elasticity were measured with a tactile sensor(Venustron, Axiom Co., JAPAN) while subjects were asked to relax and perform various parafunctional activities such unilateral clenching(biting the bite force recorder with a force of 50kg on each subject's preferred side), jaw thrusting and lip bracing. The following muscles were examined: temporalis anterior(Ta), masseter(Mm), frontalis(Fr), inferior orbicularis oculi(OOci), zygomaticus major(Zm), superior and inferior orbularis oris(OOrs and OOri) and mentalis(Mn). Paired t-test, Correlation Coefficients, ANOVA and Multiple Comparison t-tests were used for statistical analysis. Unilateral clenching was highly correlated with bilateral stiffness and elasticity of all the muscles tested. Mm was affected by all three oral habits; Ta was affected by unilateral clenching(p<0.05); Zm was affected by unilateral clenching and OOrs, OOri and Mn were most affected by lip bracing(p<0.05). This study indicates that not only the masticatory muscles but also the muscles of facial expression, mainly circumoral muscles, can be significantly influenced by parafunctional activities such as unilateral clenching and lip bracing.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.1
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• pp.50-57
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• 2020

The loss of posterior support and the abnormal jaw relation can cause pathologic findings. If deep bite patients with multiple missing teeth, can not have the stable posterior contact, the mandible moves posteriorly, and consequently the overjet and overbite get worse. And when the mandibular irregular occlusal plane is corrected, it is easier to have the bilateral balanced occlusion with the maxilla. So the treatment goal is to give proper posetrior support and establish appropriate anterior guidance, and ultimately provide improved mastication and esthetics recovery. In this case, a 68 year old man, having deep bite without posterior support was evaluated by the vertical dimesion decision flow-chart. An available prosthetic height, anterior occlusal relation such as overjet, overbite and the esthetic part such as facial height and the cephalometric analysis are the factors to be considered.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.1
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• pp.19-28
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• 2022

In removable partial dentures, abutment teeth are essential for support, maintenance, and stability of partial dentures, and are an important factor in the fabrication of functional dentures. If the number of periodontally sound abutments is sufficient and they are located on both sides, it will be easy to manufacture functional dentures with good support, maintenance, and stability. But on the contrary, if the number of teeth is insufficient or if they are located on one side, it is biomechanically disadvantageous and relatively difficult to make functional denture. On the other hand, recently, implant-supported removable dentures, which reinforce the three elements of maintenance, support, and stability by using implant surveyed crown, have been frequently selected as treatment plans. In particular, by adding an implant surveyed crown when only a small number of residual teeth remain, mastication efficiency, esthetics, patient comfort, and pronunciation can be improved. In this case, bilateral posterior extension partial denture was fabricated using implant surveyed crown as abutments by placing implants in the premolars area opposite to the residual tooth unilaterally in the mandible. As a result, the asymmetry of the abutment was resolved, and the maintenance and stability of the denture was achieved.

• Journal of Oral Medicine and Pain
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• v.32 no.3
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• pp.337-346
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• 2007

This study aimed to evaluate a relation of bruxism with clinical effects of botulinum toxin type A(BTX-A) injection. 5 bruxers and 5 nonbruxers with bilateral masseter hypertrophy were participated in this study. After injecting 25 unit of BTX-A(Allergen Inc, $Botox^{(R)}$) into each masseter muscle, the thickness of masseter(Mm) and anterior temporalis(Ta) muscles was measured by ultrasonography and the maximum bite force was evaluated during a 9-month period. Self-estimation on the recovery of occlusal force during mastication was done as well. Regardless of presence of bruxsim, all subjects showed significantly reduced Ms thickness(p<0.001) and maximum bite force at $1^{st}$ molars(p=0.027) with their peak at 3 months after injection, which then started to return. No significant difference was observed in Ta thickness and the bite force at the central incisors. While self-estimated occlusal force was the least at 2 weeks after injection and then rapidly returned to the baseline level with full recovery at the time of 6 to 9 months after injection, the maximum bite force measured by bite force recorder did not recover the original value, particularly in the nonbruxer group. It is assumed that nocturnal bruxism can influence recovery of atrophic masseter and decreased occlusal force due to BTX-A injection. These findings suggest a need of occlusal appliance to control bruxism or clenching habit for longer clinical effect of BTX-A injection.