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REVIEW ARTICLE
Year : 2020  |  Volume : 12  |  Issue : 5  |  Page : 2-5  

Is neutral zone, patients comfort zone? A feedback review


Department of Prosthodontics and Crown & Bridge Malabar Dental College and Research Centre, Malappuram, Kerala, India

Date of Submission29-Jan-2020
Date of Decision01-Feb-2020
Date of Acceptance02-Mar-2020
Date of Web Publication28-Aug-2020

Correspondence Address:
Dr. V Beenu
Malabar Dental College and Research Centre, Manoor–Chekanoor Road, Manoor, Edappal, Malappuram, Kerala.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jpbs.JPBS_56_20

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   Abstract 

The technique of neutral zone is useful. It is the convergence of many concepts and ideas into a feasible and functional method. The technique aims to build a denture in accordance with the underlying oral structures that are formed by muscle function. It acts as an alternative technique in case of highly atrophic ridges. With a history of denture instability, it is most successful. This paper seeks to provide information with an enclosure of a patient input study to use the technique.

Keywords: Atrophy, comfort, neutral zone, stability


How to cite this article:
Beenu V, Kattak AK, Pattath VS, Nair SJ, Das R, Sreelekshmi M S. Is neutral zone, patients comfort zone? A feedback review. J Pharm Bioall Sci 2020;12, Suppl S1:2-5

How to cite this URL:
Beenu V, Kattak AK, Pattath VS, Nair SJ, Das R, Sreelekshmi M S. Is neutral zone, patients comfort zone? A feedback review. J Pharm Bioall Sci [serial online] 2020 [cited 2020 Nov 26];12, Suppl S1:2-5. Available from: https://www.jpbsonline.org/text.asp?2020/12/5/2/292879




   Introduction Top


Population life expectancy is steadily increasing.[1] In the present world, people are aware and concerned about their health and, later in life, people experience tooth loss. Elderly patients have extreme ridge atrophy, especially those who are long-time denture. We even undergo lip and cheek muscular atrophy.[2] Previously complete adaptation of the denture was no problem as new wearers of the dentures were younger.[3] An alternative approach for conventional denture is required in case of a highly atrophied ridge. Dental implant is a good option because it provides stabilization for a denture. But due to many reasons such as cost factors or medical conditions, implants cannot be given in all cases.[4] Complete dentures need to be designed in a manner so that they adhere to normal neuromuscular activity.[5] If there is any failure in recognizing the relevance of the location of the tooth and the shape and contour of the flange, it can cause unstable dentures. There should be coordination between complete dentures and neuromuscular activity.[6]


   Neutral Zone Top


Fish[7] and R. W. Tench (personal communication, 1952) are the two people who have likely contributed the most to these principles. The neutral zone is a possible denture area within the oral cavity in which the movements of the tongue pushing toward the outside are neutralized by the pressures of the lips and cheeks pushing inwards.

According to the Glossary of prosthodontic terms: ninth edition, the neutral zone is defined as the potential space between the lips and cheeks on one side and the tongue on the other, that area or position where the forces between the tongue and cheeks or lips are equal.[8] There are two factors that influence the neutral zone. These are alveolar residual ridges and tongue.[9] The position of teeth should be buccolingually on the residual alveolar ridge.[10] The position of the teeth must be precisely such that the muscle forces appear to balance the denture instead of unseating it.[5] There should be coordination between the tongue, teeth, and buccinator for better denture construction.[11]


   Muscles and Neutral Zone Top


It is very important to recognize and use these forces generally resulting from muscle function in a way that promotes dental stabilization. This can only be performed if we have a clear understanding of the neutral zone. Major muscles involved are buccinator, modiolus, tongue, and orbicularis oris. The neutral zone technique ensures the right position of the tooth to enable these muscle forces to balance during activity or function.[4] The neutral zone technique can thus enhance the stability of the denture.

Denture surfaces

In 1948, Sir Wilfred Fish[7] categorized a denture containing three surfaces. The first surface, the surface of impression, is that portion of the denture that is in interaction with tissues on which the denture lies and defines denture retention. The second surface, the occlusal surface is that area in contact with the teeth, either natural or artificial of the opposite jaw. Third surface, polished or external surface as termed by Fish, is all the remaining dentures that are not component of the other two surfaces. The polished surface is associated with denture retention.[12] In cases of severe ridge resorption, the more stability of the dentures and their retention depends on the outer surface.[13] The artificial teeth must be positioned in estimated positions the natural teeth occupied.[14]

Clinical case series

In our department, 10 patients of age groups between 60 and 65 years were randomly selected. Completely healed ridges with highly resorbed mandible were noticed in all cases [Figure 1]. For each patient, two sets of complete dentures were fabricated, one was fabricated conventionally and the other was fabricated with the concept of a neutral zone. The conventional denture was fabricated according to patients’ satisfactory esthetics. Patients were reviewed after 24, 48, and 72 h. Patients were instructed to use it for 2 months. After 2 months, patients were recalled for the fabrication of the principle neutral zone denture.
Figure 1: Preoperative

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Phases of neutral zone impression technique

  1. Primary impression


  2. Secondary impression


  3. Jaw relation [Figure 2]


  4. Vertical dimension was maintained


  5. One anterior and two occlusal stoppers [Figure 3]


  6. Neutral zone impression


  7. Wax try-in [Figure 4]


  8. 8. Acrylization and finishing of complete denture [Figure 5] and [Figure 6]


  9. Review after 24, 48, and 72 h [Figure 7]


  10. Review after 1 month
Figure 2: Jaw relation

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Figure 3: One anterior and two occlusal stoppers

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Figure 4: (A) Neutral zone recorded. (B) Neutral zone

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Figure 5: Putty index

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Figure 6: Acrylization and finishing of complete denture

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Figure 7: Postoperative

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Patient comfort and overall satisfaction were assessed through patient feedback analysis. Patients were more satisfied with the second denture, which was constructed using the neutral zone technique.


   Conclusion Top


The primary goal of a complete denture is to fulfill three basic requirements that include maximum comfort, masticatory efficiency, and esthetics. With the help of neutral zone technique, a denture can be constructed in harmony with muscle balance. Muscle function is the key stabilizing and retentive component while working. Complete dentures made using neutral zone technique show increased stability, retention, and comfort. From the patients’ perspective, it improved overall patient satisfaction as well as the confidence to speak and smile.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Tinker A Ageing in the United Kingdom: What does this mean for dentistry? Br Dent J 2003;194:369-72.  Back to cited text no. 1
    
2.
Lammie GA Aging changes and the complete lower denture. J Prosthet Dent 1956;6:450-64.  Back to cited text no. 2
    
3.
Miller WP, Monteith B, Heath MR The effect of variation of the lingual shape of mandibular complete dentures on lingual resistance to lifting forces. Gerodontology 1998;15:113-9.  Back to cited text no. 3
    
4.
Gahan MJ, Walmsley AD The neutral zone impression revisited. Br Dent J 2005;198:269-72.  Back to cited text no. 4
    
5.
Beresin VE, Schiesser FJ The neutral zone in complete dentures. 1976. J Prosthet Dent 2006;95:93-100; discussion 100-1.  Back to cited text no. 5
    
6.
Beresin VE, Schiesser FJ The neutral zone in complete dentures. J Prosthet Dent 1976;36:356-67.  Back to cited text no. 6
    
7.
Fish EW Principles of full denture prosthesis. 7th ed. London, UK: Staples Press; 1948.  Back to cited text no. 7
    
8.
The glossary of prosthodontic terms: ninth edition. J Prosthet Dent 2017;117:e1-105.  Back to cited text no. 8
    
9.
Fahmi FM The position of the neutral zone in relation to the alveolar ridge. J Prosthet Dent 1992;67:805-9.  Back to cited text no. 9
    
10.
Heartwell CM, Rahn AO Syllabus of complete dentures. 4th ed. Philadelphia, PA: Lea & Febiger; 1986. p. 357.  Back to cited text no. 10
    
11.
Wright CR Evaluation of the factors necessary to develop stability in mandibular dentures. J Prosthet Dent 1966;16:414-30.  Back to cited text no. 11
    
12.
Murphy WM The neutral zone and the polished surfaces of full dentures. Dent Pract Dent Rec 1966;16:244-8.  Back to cited text no. 12
    
13.
Sheppard IM Denture base dislodgement during mastication. J Prosthet Dent 1963;13:462-8.  Back to cited text no. 13
    
14.
Watt DM Tooth positions on complete dentures. J Dent 1978;6:147-60.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]



 

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  In this article
    Abstract
   Introduction
   Neutral Zone
    Muscles and Neut...
   Conclusion
    References
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