On that day, during a professional consultation, I suddenly received an urgent mission. An elderly patient named Mr. Wang had a car accident and knocked his front tooth. He came to my clinic anxiously and asked me what to do. He was worried whether the tooth needed to be extracted and replaced with a dental implant.

什麼狀況容易牙齒斷裂?There are several factors that can cause teeth to fracture


我們可以分為三方面來討論 some of the common reasons include:


外力External forces


Car accidents, impact from external forces, biting hard objects, or habitual chewing of betel nut are common causes of tooth fractures.

病理性因素Pathological factors


Deep cavities or teeth wear can cause damage to the tooth structure, and overdeveloped biting muscles and excessive biting force can exceed the strength that teeth can bear, both of which can lead to tooth fractures.

咬合因素Malocclusion factors


Abnormal Malocclusion relationships, such as deep bites or crossbites, often exert additional force on certain teeth, resulting in a higher risk of fracture than normal teeth.



牙齒斷了還有救嗎?Is there still a way to save a broken tooth?


我們可以把牙齒斷裂分為幾種情況We can categorize tooth fractures into several types 

1.斷裂面在牙齦上方Fracture above the gumline:


If the fracture is above the gumline, there is a good chance that the tooth can be saved. For small fractures, resin filling can be used for repair. For larger fractures, a dental prosthesis may be recommended for repair. If the fracture has damaged the pulp, root canal therapy may be required in conjunction with the repair.




If part of the tooth fracture is below the gingival, the first step in determining whether the tooth can be saved is usually to evaluate the ratio of the tooth crown to root (Crown/root ration).From the fracture surface 2mm below the tooth crown to the top of the tooth is the tooth crown length, and from the root tip is the tooth root length. The ratio of tooth crown length to tooth root length determines the retention or loss of the tooth.The proportion of the crown and root can be roughly determined from an X-ray to decide whether to keep or remove the tooth.

If the tooth crown/root ratio is <1:1, it means that your tooth root is longer than the tooth crown, which makes the tooth more stable. If the tooth crown to root ratio is >1:1, it means that your tooth crown is longer than the tooth root, and there may be a risk of instability. In this case, it is recommended to extract the tooth and consider treatment options such as a dental bridge or dental implant.

3.斷裂面長且橫跨牙根Fracture line is long and transverse across the root of the tooth


When this situation occurs, the tooth usually needs to be extracted. At this point, dental implants or bridges can be considered to restore function and aesthetics.”



牙冠牙根比例對於預後的影響Impact of Crown-to-Root Ratio on Prognosis





Under normal circumstances, the crown of a tooth (the part that is visible above the gumline) is always shorter than the root (the part within the gum). This ensures a balanced structure. When a tooth fractures, in order to provide adequate coverage for a dental prosthesis, the margin of the prosthesis is extended towards the root, resulting in a longer crown and a shorter root, thereby altering the crown-to-root ratio. Currently, the maximum acceptable ratio is considered to be 1:1. Ratios greater than this indicate that the crown is longer than the root, which can lead to instability and tooth mobility.

Therefore, when considering whether a broken tooth can be saved, the crown-to-root ratio is one of the key factors to consider. If your roots are naturally longer than those of others, you have a greater chance of preserving the tooth.



什麼是牙冠增長術,斷牙的救星?What is Crown Lengthening, the Savior for Broken Teeth?



牙冠增長術通常分為兩種:1. 單純手術,沒有搭配矯正。 2. 搭配矯正,先矯正後再手術。

Crown lengthening surgery is typically classified into two types: 1. Purely surgical approach without orthodontic treatment. 2. Combination with orthodontic treatment, where orthodontic alignment is performed prior to the surgical procedure.


牙冠增長術,沒有加上矯正 Crown Lengthening Procedure, Without Orthodontic Treatment



Purely surgical, the procedure involves lowering the surrounding soft and hard tissues around the tooth towards the root, exposing sufficient tooth structure for restoration. The crown of the tooth becomes longer while the root becomes shorter, resulting in a lower gum line compared to the adjacent teeth. This technique is more suitable for non-aesthetic areas where the appearance of the gum line is less critical.

牙冠增長術,加上矯正 Crown Lengthening Procedure, With Orthodontic Treatment


In conjunction with orthodontic treatment, the purpose of combining it with surgery is to first elevate the teeth and then lower the surrounding soft and hard tissues to achieve a gum line that matches the height of the surrounding teeth. This approach is recommended for aesthetic areas where achieving a harmonious gum line is important. In addition to improving aesthetics, the crown-to-root ratio is also likely to be more favorable compared to a purely surgical approach. However, it is important to note that this treatment option requires a longer duration and additional orthodontic costs.

兩種牙冠增長術的比較Comparison of Two Types of Crown Lengthening Procedures

  1. Purely Surgical Approach without Orthodontic Treatment:
  • Purpose: The primary goal is to lower the surrounding soft and hard tissues to expose more tooth structure for restoration.
  • Suitable Areas: This approach is typically recommended for non-aesthetic areas where the appearance of the gumline is less crucial.
  • Crown-to-Root Ratio: The crown-to-root ratio may not be significantly improved compared to the initial state of the broken tooth.
  • Procedure: The surgery involves removing excess gum tissue and, if necessary, reshaping the underlying bone to achieve the desired gumline height.
  • Advantages: The procedure is relatively straightforward, and the treatment duration is usually shorter compared to the combined approach.
  • Disadvantages: The aesthetic outcome may be less optimal, and the crown-to-root ratio may not be significantly improved.
  1. Combination with Orthodontic Treatment:
  • Purpose: The objective is to first reposition the teeth orthodontically to achieve proper alignment and then perform the surgical procedure to create an aesthetically pleasing gumline.
  • Suitable Areas: This approach is recommended for aesthetic areas where achieving an ideal gumline height is crucial.
  • Crown-to-Root Ratio: The crown-to-root ratio is typically improved compared to the initial state of the broken tooth, resulting in a more favorable outcome.
  • Procedure: The treatment involves orthodontic treatment to align the teeth properly, followed by surgical crown lengthening to adjust the gumline.
  • Advantages: The aesthetic result is generally superior, and the crown-to-root ratio is often improved.
  • Disadvantages: The treatment duration is longer due to the sequential nature of orthodontic and surgical procedures, and there may be additional costs associated with orthodontic treatment.

Ultimately, the choice between the two approaches depends on the specific case, the aesthetic considerations, and the desired outcome. Consulting with a dental professional can help determine the most appropriate approach for crown lengthening based on individual circumstances.


牙齒斷了,有救嗎?Can a Broken Tooth Be Saved?

When a tooth is broken, several factors need to be considered to determine if it can be saved:

  1. Condition of the Broken Tooth: The extent of the tooth fracture and the presence of any underlying decay or infection will be assessed. If the damage is minimal and the tooth’s structure can be restored, there is a higher chance of saving the tooth.
  2. Cause of the Tooth Fracture: Understanding why the tooth broke is crucial in preventing future fractures. Common causes include trauma from accidents, biting into hard objects, or weakened tooth structure due to decay or previous dental treatments.
  3. Evaluation of the Overall Bite: The alignment and occlusion (bite) of the teeth play a role in determining the prognosis of a broken tooth. If the bite is misaligned or there is excessive force on the affected tooth, it may be more prone to further damage.

By considering these factors, a dentist can determine the appropriate treatment plan to save the broken tooth. This may involve procedures such as dental bonding, dental crowns, root canal treatment, or in severe cases, extraction followed by a prosthetic replacement. Regular dental check-ups and maintaining good oral hygiene are essential in preventing future tooth fractures and preserving oral health.