亞洲族群中的自然牙和人工植牙在軟組織移植後的組織形態變化

Changes in soft tissues around natural teeth and dental implants following phenotype modification therapies in an Asian population

林意萍(I-Ping Lin)

指導教授 ： 郭彥彬

國立臺灣大學/醫學院/臨床牙醫學研究所/博士(2022年)

https://doi.org/10.6342/NTU202200640

摘要

背景：
軟組織移植手術（Phenotype modification therapy, PMT） 的重要性，在近年來重新受到重視。在自然牙上，有足夠厚度的牙齦，可以幫助病患維持好的口腔衛生，降低發炎指數，更可以避免未來出現牙齦退縮、刷牙磨耗、敏感、不美觀等問題，在人工植體上，好的植體周圍軟組織除了是重建美觀的關鍵因素之一，更是和植體周圍的骨脊穩定度與降低植體周圍炎發生率有相關。此外，過往多篇研究指出，亞洲族群的牙齦形態比西方白人薄，薄的牙齦形態使牙周、假牙、矯正與植體相關治療都變的更加困難，然而，雖然軟組織移植有其重要性，但供給區的併發症像是流血、疼痛等問題，也讓很多病患不願意接受治療，某些病患會選擇服用安眠鎮靜藥物，降低壓力以接受治療。最常使用且被認為效果最佳的軟組織移植手術包含皮下結締組織(Connective tissue graft, CTG)和游離牙齦移植(Free gingival graft, FGG)，因兩者有不同的優缺點與組織特性，前者多用於前牙區，後者多用於後牙區。由於自然牙和人工植體周圍的組織形態特性也不相同，因此，本研究針對亞洲族群，觀察與比較有作過皮下結締組織（CTG）與沒有作過CTG的自然牙以及有作過游離牙齦移植(Free gingival graft, FGG)人工植體上，在術後的追蹤時，牙齦厚度、軟組織收縮率、供給區傷口癒合狀況以及植體周圍軟組織立體形態等變化，並且探討可能的影響因子。
材料及方法：
本研究分四部份作資料收集與分析。第一部分為觀察自然牙上接受過皮下結締組織移植後的牙齦厚度變化，實驗總共納入111皮下結締組織移植過的自然牙，與相鄰57個沒有接受移植的自然牙做比較，以牙周探針在牙齦邊緣下方2 mm 的位置，垂直牙齒長軸作量測，並與相關因子如牙齒位置與時間作分析。第二部分為觀察人工植體上進行游離牙齦移植(Free gingival graft, FGG)時，游離牙齦的收縮率以及分析對術後植體周圍角化黏膜的影響，實驗總共納入77隻接受過游離牙齦移植的人工植體，量測手術時游離牙齦的表面積與術後新形成植體周圍角化黏膜的表面積，利用立體數位科技技術作計算，並與相關因子如游離牙齦的大小、植體位置、性別與年紀作分析。第三部分為觀察人工植體上進行游離牙齦移植時，比較有服用與沒有服用安眠鎮靜藥物 （5 mg diazepam）的病患，供給區的傷口癒合狀況，實驗總共納入34位病患，23位術前決定服用藥物，11位則否，以過氧化氫與臨床觀察評估供給區在術後14天的傷口癒合狀況，並使用試管（Salivette）收集手術當天與術後第7天9:00 am 的口水，以酵素免疫分析法分析體內褪黑激素的變化，並且以問卷紀錄病患術前與術後服藥狀況、感受壓力與睡眠品質狀況。第四部分為觀察人工植體在進行游離牙齦移植以及裝置假牙後，植體周圍軟組織的形態與假牙外形間的關係，實驗總共納入53隻植體，在回診時，利用口腔掃描儀(3Shape) 紀錄出3度空間中的植體位置、組織形態與假牙外形，並用數位軟體，測量數值並作統計分析。
結果：
第一部分的實驗顯示亞洲族群的自然牙，平均牙齦厚度為0.96 ± 0.40 mm，經過皮下結締組織移植後，平均牙齦厚度增加為1.99 ± 0.62 mm，此部分有統計上顯著的差異性。在所有有接受皮下結締組織移植的牙齒中，上顎小臼齒的比例最高，接受手術的原因為牙齒高度敏感，希望手術能達到牙根覆蓋以及牙齦組織增厚，降低敏感與未來牙齦退縮的機會。此外，平均牙齦厚度在下顎大臼齒最厚，在下顎前牙最薄，在追蹤的各時期間，平均牙齦厚度沒有統計上的差異性。第二部分的實驗顯示後牙區域的人工植體，在術後平均12.45 ±7.73個月的追蹤，平均游離牙齦的收縮率為24.76 ±14.77 %，平均的植體周圍角化黏膜寬度為4.16 ±1.77 mm。統計分析顯示游離牙齦的面積大小越大，平均收縮率就越高。相關因子如植體位置、性別、年紀則沒有統計上顯著的差異性。第三部分的實驗發現，接受游離牙齦組之移植的病患，在第14天回診時，服用安眠鎮靜藥物的病患中，65.2% 在供給區的傷口已達到完全癒合的狀態，無服用安眠鎮靜藥物的病患中，只有35.7% 在供給區的傷口有達到完全癒合的狀態。有服用藥物的病患，術後褪黑激素相較於無服藥者高。此外，分析在第14天回診時，供給區的傷口就達到完全癒合情況的病患，這些病患術前的褪黑激素相較於無完全癒合的病患高。第四部分的實驗顯示人工植體在進行游離牙齦移植以及裝置假牙後，植體周圍垂直軟組織的高度在頰側為2.65 ± 0.75 mm、在近心側為3.74 ± 1.22 mm，在遠心側為3.16 ± 1.08 mm，在舌側為2.53 ± 0.92 mm。植體周圍水平軟組織的厚度在頰側為1.45 ± 0.53 mm，在舌側為1.05 ± 0.43 mm (P= 0.008)。在頰側的假牙萌出角度（emergence angle, EA）為EA>30時，相較於為EA30的假牙，植體周圍垂直軟組織的高度較小且水平軟組織的厚度較大。在鄰接面的假牙萌出角度為EA30時，相較於為EA30的假牙，有較多的骨脊喪失。平均的植體周圍角化黏膜寬度為4.08 ±1.10 mm。
結論：
本研究發現皮下結締組織移植手術是一個有效調整軟組織形態的治療方式，在亞洲族群中，接受移植後，平均可達將近2 mm 的牙齦厚度，並且在近3年的追蹤期間，表現都很穩定。研究中的量化數值可以提醒臨床醫師有時需要將軟組織移植手術納入假牙與矯正的治療中，以達到最佳的整體治療效果。此外，本實驗也發現游離牙齦移植手術也是一個有效調整軟組織形態的治療方式，只要有移植足夠大小的游離牙齦，後牙的人工植體在假牙裝置後，仍是有理想的角化黏膜寬度與立體空間上的軟組織形態。同時，我們也發現給予病患短期服用安眠鎮靜藥物，可以維持術後褪黑激素的濃度，促進供給區的傷口癒合，以及可以鼓勵病患接受軟組織移植手術。最後，建議人工植體的假牙製作，萌出角度應30，可以保留最多垂直軟組織厚度與維持骨脊的穩定度。綜合以上結果，軟組織移植手術（PMT）包含皮下結締組織移植（CTG）與游離牙齦移植(FGG)皆可以成功改變自然牙與植體周圍的組織形態，增進牙周組織的健康與穩定性。

關鍵字

軟組織移植 ； 皮下結締組織移植 ； 游離牙齦移植 ； 牙齦厚度 ； 收縮率 ； 傷口癒合 ； 褪黑激素 ； 角化黏膜寬度 ； 垂直軟組織厚度 ； 骨脊穩定度 ； 萌出角度

並列摘要

Background/Purpose:
The importance of phenotype modification therapy (PMT) around teeth and implants has been emphasized recently. It has been reported that a thick gingival phenotype has less gingival recession and better surgical and restorative treatment outcomes than a thin phenotype. Similarly, it has been noted that a thick peri-implant phenotype has crestal bone stability and better esthetics compared with a thin one. However, most Asian people display a thin gingival phenotype and literature regarding the amount of achieved gingival thickness after PMT is scarce, especially for the Asian population. Moreover, data on the shrinkage of soft tissue grafts vary in the literature and there has been little discussion about the influence of restorative treatments on keratinized mucosa width (KMW). In addition, donor site morbidity has always been a concern for patients and clinicians. Therefore, the objectives of this research are as follows: to analyze post-surgical gingival thickness around natural teeth after receiving a connective tissue graft (CTG) in the Asian population; to assess its tissue stability; to assess the dimensional changes of a free gingival graft (FGG) in posterior implants and their influencing factors; to analyze the rate of palatal wound healing following FGG procedures in patients taking a sedative medicine for 8 days; to analyze the tissue morphology around implant-supported prostheses by digital technology; and to evaluate the effect of prosthetic contours on the changes in tissue following FGG procedures. 
Materials and methods:
This research consists of 4 parts. In the first part of this study, 28 Asian patients who had undergone CTG surgery were recruited. In total, 111 grafted teeth and 57 nearby nongrafted teeth were selected. Gingival thickness was measured by transgingival probing, at the level of 2 mm below the mid-buccal gingival margin. The mean tissue thickness of the grafted teeth was compared to adjacent nongrafted teeth in the same individuals and the thickness in different tooth types was calculated. The gingival thickness of the grafted teeth was statistically analyzed after various time intervals. In the second part of the study, a total of 77 implants in 40 patients who had undergone FGG procedures were examined. Graft sizes during surgery and the surface areas of keratinized mucosa in the follow-up visit after restorations were compared by digital analysis, and verified by clinical measurement and photographs. The association between shrinkage and its related factors, such as graft sizes, implant location, sex and the age of the patients was evaluated. The influence of the shrinkage of FGG on the KMW following restorations was analyzed and discussed. In the third part of the study, a total of 40 FGG procedures on 58 implants and 6 teeth in 34 patients were included. Twenty-three patients decided to take a sedative medication and the rest served as a control group. The only difference between the two groups is the sedative medication, 5 mg diazepam, starting from the night before surgery. Direct examination, photographs and H2O2 were used to evaluate the healing rate by assessing the amount of wound epithelialization on day 14. Saliva samples were collected around 9:00 am on Day 0 and Day 7 to assess the melatonin level. Self-report questionnaires were filled in to record the times of taking the medicine. In the fourth part of the study, a total of 53 implants which had previously presented insufficient KMW and received FGGs were selected. At the follow-up visits, the implant position and tissue condition were documented with an oral scanner. The VT, HT and emergence angle (EA) of the prostheses were assessed by 3Shape analyzing software. The final KMW was measured by clinical assessment. Marginal bone loss (MBL) was calculated in the follow-up bitewing radiographs.
Results:
In the first part, the average gingival thickness after a CTG is 1.99 ± 0.62 mm compared to 0.96 ± 0.40 mm with nongrafted teeth, regardless of tooth type. A statistically significant difference was seen in gingival thickness between grafted and nongrafted teeth. The maxillary premolar is the tooth type that underwent CTG surgery most frequently in our study. The main reasons for this procedure were to obtain root coverage to reduce hypersensitivity and gingival augmentation to prevent future recession. Following connective tissue grafting for various clinical scenarios, mandibular molars showed the thickest gingival tissues whereas mandibular incisors presented the thinnest tissues. No statistically significant difference in the mean tissue thickness at different time intervals was observed. In the second part, the overall shrinkage of FGG around implants in posterior regions was 24.76 ± 14.77% and the average KMW was 4.16 ± 1.77 mm in the follow-up visit. Statistical analysis showed that the larger the graft, the higher the shrinkage ratio. No statistically significant difference regarding the effect of implant location, sex and age on the shrinkage of FGG and final KMW was found. The mean follow-up period after restorations was 12.45 ± 7.73 months. In the third part, 65.2% of the patients with diazepam demonstrated complete epithelialization on palatal wounds on Day 14, whereas only 35.7% in the control group presented complete wound healing. Individuals with diazepam had higher levels of post-operative melatonin in comparison with subjects who did not. Groups with complete epithelialization by Day 14 tended to present higher levels of pre-operative melatonin than those without. In the fourth part, the mean VT was 2.65 ± 0.75 mm at the mid-buccal sites, 3.74 ± 1.22 mm at the mesial, 3.16 ± 1.08 mm at the distal, and 2.53 ± 0.92 at the mid-lingual aspects. The mid-buccal HT was 1.45 ± 0.53 mm while the mid-lingual was 1.05 ± 0.43 mm (P= 0.008). Interestingly, prostheses with mid-buccal EA30 exhibited slightly lower VT, but higher HT, than the ones with EA 30. Prostheses with proximal EA30 displayed slightly more MBL, compared to prostheses with EA 30. The mean KMW was 4.08 ± 1.10 mm.
Conclusion
Firstly, CTG surgery is a predictable treatment modality around natural teeth, even in Asians, achieving nearly 2 mm of gingival thickness on average, post-operation. Tissue stability after CTG has been presented in our study in the follow-up visit up to 3.5 years. This quantitative assessment of the gingival thickness in Asians may encourage clinicians to deal with soft tissue architecture ahead of main surgical, restorative and orthodontic treatments in order to achieve the best overall treatment outcomes. Secondly, FGG surgery is a predictable treatment approach around dental implants because ideal KMW and 3-dimensional soft tissues in the posterior regions can be augmented after the fabrication of prostheses, as long as a sufficient amount of grafts is utilized. Thirdly, short-term sedative medications may encourage patients to receive the required soft tissue grafting and facilitate wound healing by means of maintaining postoperative melatonin levels. Lastly, prostheses with EA 30 were preferable for preserving the maximal VT and maintaining crestal bone stability. Overall, phenotype modification therapy including CTG and FGG can successfully convert the thin into thick phenotypes 3-dimensionally around natural teeth and implants for their long-term health and stability.

並列關鍵字

Soft tissue graft ； connective tissue graft ； free gingival graft ； gingival thickness ； shrinkage ； wound healing ； melatonin ； keratinized mucosa width ； vertical soft tissue thickness ； crestal bone stability ； emergence angle

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