Oral Biology Research, 2017; December 31, 41(4):251-255 Copyright c 2017, Oral Biology Research Institute DOI: 10.21851/obr.41.04.201712.251 Case Report ORAL BIOLOGY RESEARCH Application of neutral zone concept in order to improve denture stability in a patient with hemifacial spasm: a case report Nuri Seo, Bo-Young Ma, Hyun-Pil Lim, Chan Park, and Kwi-Dug Yun* Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju 61186, Republic of Korea (Received Sep 21, 2017; Revised version received Oct 12, 2017; Accepted Oct 24, 2017) ABSTRACT Hemifacial spasm is characterized by symptoms of intermittent, irregular and involuntary movements ( twitching ) affecting the facial muscles that are controlled by the facial nerves unilaterally affecting one side of the face only. The demographics of this neurologic problem indicates incidence far more common in females than males, and it is usually seen in the fifth decade of life, or later. Edentulous patients with involuntary movements of facial muscles (such as hemifacial spasm) could encounter difficulties in maintaining the stability of their dentures. Not only would the proper and effective occlusion of thedentures be adversely affected, the harmony and compatibility with surrounding tissues (critical factors to be considered in any effort to fabricate a stable set of dentures) could be significantly degraded. This case report will therefore present and advance the concept of fabrication of complete and completely stable and wellfitting - dentures incorporating the concept of Neutral Zone. KEY WORDS: Complete denture, External impression, Hemifacial spasm, Neutral zone 서 론 편측안면경련 (hemifacial spasm) 은안면신경지배영역의근육의간헐적, 돌발적, 불수의적인수축에의하여발생하는반측안면의운동기능항진의증상을말하는것으로여성에서발병빈도가높으며주로 50세이상에서발병한다 [1]. 무치악환자에서안면경련과같은안면근육의불수의적인움직임은의치의유지와안정을어렵게할수있다. 이러한경우안정적인의치를제작하기위해서는의치 의교합뿐아니라주변근육조직과의조화가중요한요소가될수있고, 이를위해서인공치의위치와연마면형태를적절히형성하는것이필요하다 [2]. 중립대 (neutral zone) 는혀가밖으로미는힘과볼과입술이안으로미는힘이평형을이루는근신경계기능에의한잠재적영역으로정의되며, 총의치의인공치가이영역에위치되고, 연마면형태가동적인근육의해부학적형태를따른다면근육의움직임은의치를안정시키는요소로작용할뿐아니 *Corresponding author: Kwi-Dug Yun Department of Prosthodontics, School of Dentistry, Chonnam National University, 33 Yongbong-ro, Buk-gu, Gwangju 61186, Republic of Korea Tel.: +82-62-530-5638, Fax: +82-62-530-5639 E-mail: ykd@jnu.ac.kr 라안면지지를통하여심미성또한향상될수있다는장점이있다 [3]. 본증례는편측안면경련을가진무치악환자에서중립대개념을적용하여총의치를제작하였고, 만족할만한결과를얻었다. 증례보고 본증례의환자는 80세여성으로기존에사용하던상하악총의치를분실하여, 의치를다시제작하고싶다는주소로내원하였고, 내원시우측눈에서부터입술주위까지간헐적인경련증상을가지고있었다 (Fig. 1 and 2). 환자는고혈압으로약물복용중이었고, 그밖의특이할만한의과적병력은없었다. 환자는문진시편측안면의경련증상은젊은나이에발현하였고, 50년이상지속되었으며이증상의치료를위해병원진료를받아본경험은없다고진술하였다. 무허가업자에게제작한의치를 10년이상사용하였으며, 환자는하악의치의헐거움, 특히안면경련시의치의움직임과잇몸의통증이가장큰불만이었다고하였다. 환자가전신건강및경제적인이유로임플란트식립에대한거부감을갖고있었기때문에치조제흡수및안면 - 251 -
Nuri Seo et al. Fig. 1. Initial extraoral photograph (A) and panoramic view (B) at first visit. Fig. 2. Initial intraoral photographs (A) Occlusal view of maxilla, (B) Frontal view, (C) Occlusal view of mandible. Fig. 3. (A) Lower provisional denture, (B) Sore spot on distal area of right retromolar pad. 경련증상으로인한유지및안정에있어서불리함을고지하고전통적인총의치수복을계획하였다. 기존의치사용시의치의잦은탈락과구강점막의통증에안면경련에의한협측근육과입술근육의불수의적인수축이영향을주었을것으로판단되었기때문에새로운의치제작시에협측근육을포함한안면근육의움직임과압력을고려할필요가있었다. 최종의치제작에앞서환자가기존의의치를분실하였기때문에먼저임시의치를제작하여관찰기간을갖도록하였다. 3개월의임시의치장착기간동안우측협점막과상악결절의협측치은, 우측하악치조정과후구치융기의원심측에통증을호소하여여러번의의치조정과정을거쳤다 (Fig. 3). 주로안면경련증상이있는우측에서통증이나타났고, 따라서최종의치제작시에는이러한문제를개선하기위하여협측과설측근육의압력 이균형을이루는중립대에치아를배열하고, external impression을통해근육의움직임을반영한형태의연마면을형성하기로하였다. 알지네이트 (Cavex Impressional, CAVEX, Haarlem, Netherland) 로예비인상채득하여진단모형을제작하였고 (Fig. 4A and 4D), 진단모형상에서개인트레이를제작하였다. 다음내원시모델링콤파운드로변연형성후폴리설파이드 (Perlmastic, Kerr Corp., Orange, CA, USA) 를이용하여상악과하악의기능인상을채득하고 (Fig. 4B and 4E) 최종모형을제작하였다 (Fig. 4C and 4F). 최종모형상에서금속구조물을제작한후환자에게시적시기록상과교합제을제작하여고딕아치기록법을이용해악간관계를채득하였다. 간헐적인편측안면경련의영향을최소화할수있도록반복적인고딕아치기록을통해재 - 252 -
Neutral zone concept for denture stability Fig. 4. Diagnostic model (A, D), final impression (B, E) and master cast (C, F). Fig. 5. Vertical dimension (A) and centric relation record using Gothic arch tracing (B). Fig. 6. Recording of neutral zone with compound rim (A), putty index (B), and artificial teeth arrangement according to index (C). 현성있는중심위를채득하였고, 안궁이전을시행하여이를반조절성교합기에부착하였다 (Fig. 5). 이와는별도로최종모형상에서아크릴릭레진으로기록상를제작하고 1.0 mm wire로콤파운드재료를유지하기위한골격을형성하였으며, 이후적절한온도로연화시킨모델링콤파운드를소량씩적층하면서환자의구강내에서콤파운드교합제를형성해주었다. 콤파운드교합제을구내에장착한동안연하, 혀를내밀거나입술을좌우로핥는동작, 이 (E), 오 (O) 발음등의기능운동을하게하였다. 콤파운드교합제가경화되는동안기능운동을반복하여수행하게하였으며환자의편측안면경련시근육의압력또한반영 되도록하였다 (Fig. 6A). 형성된콤파운드교합제의형태를부가중합형실리콘인상재 (Exafine Putty Type, GC Corp., Tokyo, Japan) 로인기하여 index를제작하였고 (Fig. 6B), 이를기준으로중립대내에치아가위치할수있도록인공치를배열하였다 (Fig. 6C). 해부학적치아 (Endura, Shofu Inc., Kyoto, Japan) 를이용하여설측교합양식으로교합을형성하였고, 완성된납의치를환자구강내에시적하여교합및수직고경을확인하고안모등심미성을평가한후, 연마면형성을위해외부인상을시행하였다. 연마면인상을위해상하악납의치의치은부분왁스를부분적으로제거하고부가중합형실리콘인상재 (Virtual - 253 -
Nuri Seo et al. Fig. 7. External impression. Constriction of right facial muscle during impression (A), upper labial flange impression (B), upper buccal flange impression (C), occlusal view of lower impression (D), lower labial impression (E), and lower lingual impression (F). Fig. 8. Clinical remounting (A) definitive denture delivery (B). Fig. 9. Definitive prosthesis. Upper complete denture (A, B, and C) and lower complete denture (D, E, and F). Heavy Body, Ivoclar Vivadent, Liechtenstein)를 적용하여 착 및 교합 조정을 시행하였고 연마하여 의치를 완성하였 구강 내에 시적한 후 경화 시간 동안 환자가 기능 운동을 다. 최종 의치를 환자에게 시적하여 의치상의 적합도와 심 하도록 하였다. 환자의 기능 운동과 편측안면 경련 시 근 미성을 평가하고, 교합 채득 및 안궁 이전하여 진료실 재 육의 움직임을 인기한 연마면을 형성하였다(Fig. 7). 의치 부착을 시행한 후 환자에게 장착하였다(Fig. 8). 온성 후, 중합 과정의 오차를 수정하기 위한 기공실 재부 - 254 - 완성된 새로운 의치는 중립대 개념과 외부인상을 이용
Neutral zone concept for denture stability 하여제작된연마면의특징적인형태를가지고있었다 (Fig. 9). 기능운동시와휴식상태의안면경련시향상된유지와안정을보여주었고, 환자역시기능적, 심미적인면에서새로운의치에대해만족하였다. 힘을인공치의위치와연마면의형태에반영할수있었으며, 완성된상하악총의치에서여러기능운동및안면경련시보다향상된안정과유지를보였고환자도기능적, 심미적으로만족하였다. 고 찰 Conflict of Interest 총의치환자에서근신경계와의조화는안정적인의치를제작하기위한기본적인요소이다. 인공치의위치와 flange의형태및윤곽을간과하게되면, 숙련자에의해잘만들어진의치라하더라도종종불만족스러운결과를나타내기도한다. 의치공간의내부와외부경계를형성하는연조직이작용하는힘은의치의안정에큰영향을미친다. 총의치에서중립대를통한접근법의핵심개념은무치악환경에서의치의탈락을막고안정화시킬수있도록근육들의힘이작용하는영역에인공치를위치시키는것이다. 중립대는혀, 입술, 볼에의해형성되며근육활성과습관은평생에걸쳐발달된다. 치아가상실되고나면근육의기능과활성은독립적으로기능하게되고따라서구강내에위치한의치에지대한영향력을갖게된다 [3]. 따라서기존의자연치위치에인공치를배열하는것은의치제작에있어매우중요한요소이며연마면의형태역시의치의안정에큰역할을한다 [4]. 일반적으로의치의세가지면즉, 인상면, 교합면, 연마면중에서술자들이인상면과교합면을중시하는반면, 연마면은간과하는경우가많다. 특히치아상실후오랜기간이경과하여치조제가흡수된환자에서는의치의지지영역이좁아짐에따라인상면의면적은감소하고연마면의면적은증가하게되므로치조제가충분한환자에비해인공치의위치와연마면의형태는더중요한역할을하게된다 [3, 5]. 연마면은볼, 입술그리고혀와접촉하고있으며해부학적구조에기초한다. 따라서지나치게두껍거나근육의해부학적형태를따르지않는의치상은주변근육의영향으로의치를쉽게탈락시키는요소가될수있다. 편측안면경련을가진본증례의환자에서와같이비정상적인근육의수축을가지는경우통상적인인공치배열과연마면형성시근육의움직임이의치의유지와안정을감소시킬뿐아니라지속적인의치의움직임이치은과점막을자극을야기할수있으므로임상적결과를향상시키기위해서중립대인상기법이도움이될수있다 [6, 7]. 본증례의환자의경우중립대를인기하고연마면을형성하는과정동안우측안면의경련시근육의움직임과 The authors declare that they have no competing interests. ORCID Nuri Seo 0000-0003-0291-6410 Bo-Young Ma 0000-0002-8147-056X Hyun-Pil Lim 0000-0001-5586-1404 Chan Park 0000-0000-5729-5127 Kwi-Dug Yun 0000-0002-2965-3967 References 1. Chaudhry N, Srivastava A, Joshi L. Hemifacial spasm: The past, present and future. J Neurol Sci 2015;356:27-31. doi: 10.1016/j.jns.2015.06.032. 2. Cagna DR, Massad JJ, Schiesser FJ. The neutral zone revisited: From historical concepts to modern application. J Prosthet Dent 2009;101:405-412. doi: 10.1016/ S0022-3913(09)60087-1. 3. Beresin VE, Schiesser FJ. The neutral zone in complete dentures. J Prosthet Dent 2006;95:93-100. doi: 10.1016/ j.prosdent.2005.10.005. 4. Schiesser FJ. The neutral zone and polished surfaces in complete dentures. J Prosthet Dent 1964;14:854-865. doi: 10.1016/0022-3913(64)90014-9. 5. Atwood DA. Bone loss of edentulous alveolar ridges. J Prosthet Dent 1979;50:11-21. doi: 10.1902/jop.1979.50.4s.11. 6. Rehmann P, Zenginel M, Wostmann B. Alternative procedure to improve the stability of mandibular complete dentures: a modified neutral zone technique. Int J Prosthodont 2012;25:506-508. 7. Mustafa AZ. Effect of the lingual ledge of neutral zone impression on the retention and stability of mandibular complete denture in elders with atrophied alveolar ridge. Tanta Dent J 2015;12:111-118. doi: 10.1016/j.tdj.2015.02.003. - 255 -