一、此習慣的牙齒表現：

                                                                            醫生之所以一眼看出了患者的不良習慣，是因為牙齒在“說話”。

                                                                            患者的上下前牙前突，上門牙切端有缺損，下前牙更明顯，四顆門牙切端的牙釉質幾乎全部被磨除了，牙本質隱約可見。如果光看這口牙的磨耗度，醫生會認為這是個四十歲以上的成年人。

                                                                            二、此習慣的不良影響：

                                                                            1、對於牙齒來說：前牙啃指甲，對上前牙會造成一個持續的唇向力量，長期作用之後會造成上前牙的唇向移位，造成齙牙。而指甲是相對來說比較堅硬的東西，咬合於牙齒之上會對牙齒產生一個机械的磨耗作用，磨損牙釉質，導致牙釉質的缺損以及牙本質的暴露，嚴重者牙齒會產生酸疼的過敏癥狀。

                                                                            2、對全身系統來說：指甲藏污納垢，啃指甲直接將細菌帶入了消化道，可能引起消化道感染等疾病。長期啃指甲，注意力不集中，也將影響良好學習習慣的養成。

                                                                            三、常見口腔不良習慣及後果：

                                                                                            不良習慣

                                                                                            口腔表現

                                                                                            張口呼吸

                                                                                            上頜前突、下頜后縮

                                                                                            吐舌頭

                                                                                            前牙梭形開合

                                                                                            咬上唇

                                                                                            前牙反頜“地包天”

                                                                                            咬下唇

                                                                                            開唇露齒，下頜后縮

                                                                                            咬奶嘴、被子等物品

                                                                                            局部開合

                                                                                            偏側咀嚼

                                                                                            面部發育不對稱

                                                                            四、如何防治

                                                                            1、牙齒的最佳矯正年齡是11-12歲，但如果有不良習慣，請早到醫院就診處理。

                                                                            2、替牙期間半年看一次牙醫，有利於發現患者的不良習慣，防止畸形的出現和發展。

                                                                            3、如果已經出現牙齒畸形，到正規醫院的正畸科就診，矯正已經出現的畸形。

                                                                            4、家長監控破除孩子的相關不良習慣至關重要。治好了病因，才是療效穩定的保障。

                                                                            五、可以嘗試的方法

                                                                            1、對於咬甲癖兒童，多缺乏長期有效的行為糾正方法。

                                                                            2、然而，取笑、懲罰、恐嚇，常無益於幫助孩子糾正這種行為；厭惡療法（使用苦味劑、辣椒油塗抹在指甲上）目前也存在爭議，這可能會引起逆反心理，加重焦慮。

                                                                            3、行為改變並非一朝一夕就能見效，家長和患兒應該認識到糾正的長期性，否則的話，更容易半途而廢。