• The Journal of Korean Academy of Prosthodontics
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• v.54 no.4
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• pp.407-412
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• 2016

The neutral zone technique is an alternative approach for the construction of complete dentures on highly atrophic ridges with history of denture instability. This technique achieves two objectives. First, the teeth will not interfere with the normal muscle function, and second, the force exerted by the musculature against the denture is more favorable for stability and retention. In this case of a 78-years-old female patient with severely atrophic ridges who had been using unstable complete dentures, the neutral zone impression technique was used to increase the stability and the retention of dentures. The neutral zone for both arch was located with modeling compound. After the arrangement of artificial teeth within the neutral zone, the external impression was taken to determine the tissue surface. The final dentures showed enhanced stability and retention and the patient was satisfied with the new dentures with respect to functional and esthetic aspects.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.2
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• pp.107-112
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• 2001

The prosthodontic treatment of severely resorbed edentulous patients has been one of the frustrating areas due to extensive loss of tissues. The integrated neuromuscular balance among tongue, lip, and cheek is compromised. The retention, stability, and support are the three major factors to influence the clinical outcome. Fish described a denture as having three surface, with each surface playing an independent and important role in the over all fit, stability, and comfort of the denture. He recommended that the polished surface should be a series of inclines so that pressure from muscular activity will retain dentures. Within the denture space there is an area that has been termed the neutral zone. The neutral zone is that area in the mouth where, during function, the forces of the tongue pressing outward are neutralized by the forces of the cheeks and lips pressing inward. According to Jacobson and Krol, neuromuscular control interacts to provide retention and the relationship of polished surface of denture base to the surrounding muscular structure of orofacial capsule facilitates the stability and retention. This neutral zone concept has been demonstrated with various modification by a number of authors. The theory used to develop the denture base contours is based on the belief that the muscle should functionally mold not only the border but the entire polished surface. Lott and Walsh reported the clinical success on complete mandibular dentures with application of neutral zone concept. A number of studies demonstrated that denture stability and retention are more dependent on correct position of the teeth and correct contour of external surfaces of the denture in a severely resorbed alveolar ridge. This article presents a prosthodontic approach to treatment of a edentulous patient using neutral zone technique to improve the retention and stability of the prosthesis.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.1
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• pp.18-25
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• 2023

We present the case of a 65-year-old man with maxillary and mandibular complete dentures prepared using neutral zone technique after undergoing mandibulotomy due to tonsil cancer 10 years ago. The patient had a short edentulous period; hence, there was minimal absorption of the alveolar ridge and no abnormality in the motor function of the tongue. However, the retromolar pad was located inside the hamular notch, and the posterior alveolar ridge was relatively turned inward. If the artificial teeth would have been aligned conventionally, the functional space of the tongue would have been invaded, which would have moved the tongue posteriorly thereby reducing the stability of the denture. Therefore, applying the concept of the neutral zone can be a good reference point in such cases. The neutral zone was registered using tissue conditioner, and tooth alignment was performed by making a silicone putty index. The biggest advantage of using neutral zone concept is denture stability. In this case, the neutral zone technique was applied to obtain the lingual alignment limit of the posterior teeth to avoid invasion of the tongue space by the left posterior part of the mandible. Particularly, in case of a patient in which denture stability is difficult to obtain due to absorption of the alveolar ridge, it is believed that better results can be obtained using neutral zone technique.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.32 no.1
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• pp.8-15
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• 2023

In case with severely atrophied mandibular ridges, it may be difficult to achieve adequate retention and stability of dentures through the normal functional impression process of complete dentures. In these patients, an approach using the neutral zone raising technique may be an effective alternative. The neutral zone is defined as the area where the pressure of the tongue towards the outside of the mouth and the pressure of the cheek and lips towards the inside are balanced during the normal oral function of the muscular-nervous system. Complete dentures made through neutral zone impression not only improve retention and stability, but also provide adequate tongue space in the posterior teeth area. Additionally, food residues are reduced in the area around artificial teeth, and aesthetics are improved through appropriate facial support.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.324-330
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• 2018

In order to produce a stable denture for severe alveolar bone loss area, it is not only important that .0a suitable occlusion is established but also to consider compatibility with the surrounding muscle to form a suitable polished surfaces. Neutral zone is defined as a potential area where the neuromuscular system of the tongue, cheeks and lips is balanced can be determined through the neutral zone impression technique. And if artificial teeth are aligned within the neutral zone and the polished surface follows the anatomical form of the dynamic muscle, higher stability and retention of the denture may be obtained through coordination with the surrounding muscle tissue. This case is being reported since the concept of the neutral zone was applied to a patient with severely atrophic residual alveolar ridge and the result was clinically satisfactory in both function and aesthetics.

• Journal of Environmental Science International
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• v.27 no.6
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• pp.359-369
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• 2018

A model has been developed to predict natural ventilation in a single zone building with large openings. This study first presents pressure-based equations on natural ventilation, that include the combined effect of wind and thermal buoyancy. Moreover, the concept of neutral pressure level(NPL) is introduced to consider the two-way flow through a large opening. The total pressure differences across the opening and the NPL are calculated, and nonlinear equations are solved to find the zonal pressure to satisfy mass conservation. For this analysis, an iterative technique of successively approximating the zonal pressure is used. The results of applying this study model to several simple cases are as follows. When there is no wind and only the stack effect is caused, a one-way flow occurs in both the top and bottom openings in the case of two openings of equal-area, and a one-way flow occurs in the top opening; however, a two-way flow occurs in the bottom opening in the case of two openings of unequal-area. When there is a wind effect, regardless of whether the outside air temperature is lower or higher than the indoor air temperature, air flows into the room through the bottom opening and out of the room through the top opening. As the wind velocity increases, the wind effect appears to be more influential than the stack effect owing to the temperature difference.

• YAKHAK HOEJI
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• v.41 no.5
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• pp.539-546
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• 1997

Capillary electrophoresis (CE) is perceived as an attractive tool for the analysis of pharmaceuticals and biological materials because of their high separation efficiency, easy separation and low running cost. New concept of micellar electrokinetic capillary chromatography (MECC) expanded the application of CE to the separation of neutral molecules. Validation of CE as an analytical technique for quality control of pharmaceuticals should be confirmed by quantitative analysis and the peak confirmation. In this study, the quantitative analyses of various types of neutral, acidic and basic components (acetaminophen, caffeine, ascorbic acid, riboflavin, thiamine, chlorpheniramine, phenylpropanolamine, dl-methylephedrine and dextromethorphan) in complex cold medicines have been accomplished using CE. Combined methods of MECC using SDS and capillary zone electrophoresis lowering the pH of running buffer were adopted to determine the ingredients in capsule type or liquid formula complex medicines without particular sample pretreatment. The results indicate that CE is a promising technique for quality control analysis of pharmaceuticals as a validation method.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.1
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• pp.64-69
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• 2018

Odontogenic myxoma of the jaws is a rare benign odontogenic tumor. In this case, a 61-year-old male patient had a chief complaint about maxillary anterior gingival mass and excisional biopsy result confirmed odontogenic myxoma. The clear acrylic resin custom tray was designed to minimize displacement of flabby tissue which remained after the surgery. Neutral zone and external impression technique could provide satisfactory result in terms of denture stability and retention during jaw relation record and wax denture try-in procedure. This clinical report describes fabrication of complete dentures for a patient with odontogenic myxoma in regard to flabby tissue and neutral zone.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.1
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• pp.39-45
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• 2015

Loss of continuity of the mandible destroys the balance and symmetry of mandibular function, leading to altered mandibular movements and deviation of the residual fragment towards the resected side. Apart from deviation, other dysfunctions include difficulty in swallowing, speech, mandibular movements, mastication, and respiration are accompanied. In general, surgical reconstruction is considered first then proceeds to the prosthetic restorations. However, patients with systemic disease such as BRONJ (Bisphosphonate related osteonecrosis of the Jaw), surgical reconstruction may be limited. Thus, the prosthetic restoration remains as the only resort. Numerous prosthetic methods are employed to minimize deviation and to improve masticatory efficiency, function and esthetics. If a removable partial denture is the selected treatment modality, maximum stability of the partial denture base may be accomplished with a functional impression procedure by means of eliminating lateral and horizontal forces caused by the functional movements of the lips, cheeks and tongue. Also, Twin occlusion is used to obtain a favorable occlusal relationship and check support for esthetics. The purpose of this case report is to demonstrate how neutral zone impression technique and twin occlusion scheme were applied to restore a hemi-mandiblectomy patient with BRONJ syndrome to achieve satisfactory results in functional and esthetic aspects.

• Journal of the Korean Electrochemical Society
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• v.9 no.2
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• pp.70-76
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• 2006

Micro-droplet cell with free droplet as a micro-electrochemical technique has been limited to apply to electrochemical systems with high wetting properties such as an acidic solution and low grade stainless steels(Type 316L). By loading negative pressure to a droplet, control of droplet size, and use of hydrophobic gasket, the cell is modified to be allowed to use for electrochemical systems with high wetting properties. For giving the reliability of new cell, studies on local corrosion were conducted for three different systems-an acidic chloride solution and high chromium ferritic stainless steel, the other acidic chloride solution and type 316, and a neutral chloride solution and type 316. stainless steel. Firstly, the modified micro-droplet cell allows the anodic polarization curves in an acidic chloride solution to show the fact that the local corrosion of high chromium stainless steel near the $\alpha/\sigma$ interface is due to the Cr depleted zone. Secondly, the local anodic polarization test of type 316 L in the other acidic chloride solution can be successfully conducted in the cell. Furthermore, the local polarization curves help elucidating the corrosion of type 316 with $\delta-ferrite$ phase. Finally, the polarization curves of type 316 L in a neutral chloride solution indicates that the factor affecting the pitting corrosion resistance was inclusions rather than $\delta-ferrite$.