The temporomandibular joints (TMJ) are located in front of the ears. If you use your fingers to lightly press the recess in that place and open and close your mouth, you will feel the temporomandibular joint move. Muscle pain and joint disorders are the common causes of temporomandibular joint and muscle disorder (TMD). In the case of muscle pain, it may be related to parafunctions such as gum chewing, eating hard foods, clenching and tooth grinding at night. For joint disorders, it may be related to disc displacement and inflammation. There is a cartilaginous disc between the jaw bone and temporal bone of the TMJ. If the disc becomes displaced, one may experience clicking or popping sounds during jaw function, and may contribute to pain in the TMJ or limited mouth opening. The pain may also spread to the head, face, or teeth etc.
According to the 2018 National Institute of Dental and Craniofacial Research, the prevalence of TMD is between 5% and 12%. Temporomandibular disorders are at least twice as prevalent in women as men while the rates of TMD are higher among younger persons.
Conventional approach to most types of TMDs begins with conservative treatment options, such as non-steroidal anti-inflammatory (NSAIDs), physiotherapy, soft diet and occlusal splint etc. When clinical improvement is not observed with conventional approach, arthrocentesis will be offered to patients with joint dysfunction. Arthrocentesis has been a standard treatment since the early 1990s, which involves the application of two small needles near the TMJ, and the joint is washed thoroughly with Normal Saline with the aim to clear the inflammatory substances and fibrous adhesion of the joints, and to reduce the negative pressure inside the TMJ. Arthrocentesis is a simple and safe treatment, which normally takes around 15-20 minutes in the clinical setting, with a high efficacy of 80-85%.
The question is when should the treatment progress from conventional approach to arthrocentesis? This has not been answered in any medical literature to date. Recent scientific research showed that early minimally invasive procedures may be beneficial in terms of pain reduction and improving jaw function.
Clinical Assistant Professor Dr Dion Li (Principal investigator) and Clinical Associate Professor Dr Mike Leung from the Oral and Maxillofacial Surgery of HKU Faculty of Dentistry recently applied arthrocentesis and occlusal splint as an integrated treatment for TMDs. A study with arthrocentesis as the first-line treatment was also conducted and compared to the efficacy of the conventional approach.
From the preliminary results (
Attachment 1), the research team discovered that the integrated treatment with arthrocentesis and splint was more effective compared to conservative treatment alone. After undergoing the therapy for six weeks, the pain level of patients with integrated treatment was rated at 2.6 on a rating scale of 0 to 10 with 0 being no pain and 10 being severe pain, and their maximum mouth opening (MMO) reached a normal 40.8 mm on average; while the pain level of patients with conservative treatment remained at 6.5, and the mouth opening reached a maximum of 30.5 mm. MMO for adults generally ranges from 35 to 55mm.
“In general, if symptoms last for 3 months or more, it is defined as chronic disease. The consequence of delaying effective management could result in the pain becoming chronic, which has been shown to be more difficult to treat, while early consultation and treatment is likely to provide more clinical benefits,” said Dr Li.
Dr Dion Li continued, “According to our preliminary results, we believe that the integrated treatment with arthrocentesis and occlusal splint as an early treatment for TMDs is able to achieve a more rapid clinical response and it will be a growing trend in oral and maxillofacial surgery.”
Dr Mike Leung added, “We will continue to conduct research on arthrocentesis to explore its immediate clinical effects and its efficacy, in the hope of providing more appropriate and precise treatment for patients with TMDs.”
Public Enquiry:
If you suspect that you have or have developed TMDs, please contact the Oral Maxillofacial Surgery Team at the Faculty of Dentistry of the University of Hong Kong:
About Temporomandibular Joint
video
Media Enquiry:
Faculty of Dentistry, University of Hong Kong
Senior Communications Officer, Ms Melody Tang
Tel: 2859 0494; Email:
melodytang@hku.hk
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牙骹位於耳朵前方。用手指輕按那處的凹位並開合嘴巴，便會感覺到顳下頜關節（牙骹）移動。牙骹痛源於肌肉或關節問題，前者多因肌肉勞損例如經常嘴嚼香口膠、魷魚絲或果仁等黏韌堅硬食物，或睡覺時有磨牙或咬緊牙關的習慣。後者則有機會是關節軟骨移位發炎導致 -「顳下頜關節綜合症」，其一般症狀乃「開口埋口」說話、吞嚥、打呵欠時感覺牙骹痛，有時會聽到顎骨「卡卡」聲，牙骹不能順暢開合，痛楚可延伸至面部、頭、耳和牙齒等。
根據美國國家牙科和顱面研究所2018年的數據，顳下頜關節綜合症的患病率介乎5%至12%，其中女性患病的機率較男性高兩倍，年輕人患病的比率亦較高。
關節性牙骹痛通常由保守治療開始，例如處方消炎藥、物理治療、進食柔軟食物，和使用咬合夾板（牙膠）減輕關節疼痛和改善張口度。當保守治療效用不顯著時，醫生會嘗試進行顳下頜關節沖洗術的微創療法，方法是在顎關節放入兩枝針，灌入生理鹽水沖洗關節，把發炎物質和纖維組織沖走，減低關節負壓力，亦可注入透明質酸潤滑關節。顳下頜關節沖洗術在90年代起開始普及，其風險低，成功率高達80至85%。
然而，究竟於什麼時候應該由保守治療轉到微創冲洗療法，醫學文獻暫時並未有定論。近年的研究發現，微創冲洗治療若於治療早期介入，能有效消除痛楚和改善顎骨的功能。
香港大學（港大）牙醫學院口腔頜面外科臨床助理教授李廸信醫生（首席研究員）和臨床副教授梁耀殷醫生最近以顳下頜關節沖洗術，配合咬合夾板治療作臨床研究，對比只採用保守治療的成效。
初步的研究結果顯示，沖洗術結合咬合夾板的綜合治療，比保守治療更為有效（
附件一）。經過六週的治療，接受綜合治療的病人，在從0分沒有任何疼痛至10分劇烈疼痛的評分表中，疼痛評估方面的指數大幅降低至2.6，而接受保守治療的病人則停留在6.5。在張口度（MMO）方面，一般成年人的最大張口度為35至55毫米，接受綜合治療的病人於第六週能張口平均至正常的40.8毫米，而接受保守治療的病人則只有30.5毫米。
「一般而言，關節性牙骹痛病徵持續出現三個月或以上，會被診斷為慢性痛症，這時已失去早期治療的良機，演變成慢性病，病情更難處理。若把沖洗術作為首要治療的話，便有機會預防病情演變成慢性痛症。」李廸信醫生說。
「根據我們初步的研究數據，早期的沖洗術和咬合夾板的綜合治療能達致更迅速的臨床反應，將會是口腔頜面外科的發展趨勢。」李醫生補充說。
梁耀殷醫生指出: 「我們將繼續推動顳下頜關節沖洗術的研究，以探究其即時的臨床效果和改善慢性病的成效，希望能為患有顳顎關節症的病人提供更適切和精準的治療。」
公眾人士懷疑自己患上牙骹痛，歡迎向香港大學牙醫學院口腔頜面外科團隊查詢。
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