Fixed Teeth in Reduced Mouth Opening

In the early 1900s, it was commonly thought that patients with missing teeth could not be given fixed partial dentures. However, with advances in technology and knowledge, this practice has now become common. To understand if fixed teeth can be given in a reduced mouth opening, we need to first understand what fixed teeth are and why they are given in a reduced mouth opening. Fixed teeth are essentially permanent replacement teeth that cannot be removed.

This means that they are cemented on as opposed to being connected by a chain or other removable fastener. These teeth cannot be removed before going to bed and must remain securely in place all day until they’re replaced again the next day. That is why fixed teeth have reduced openings to allow for greater retention of these artificial replacements for our natural back molars. So yes, fixed teeth can be given in a reduced mouth opening.

Who is This Article For?

This article is for patients who have missing teeth but also have reduced mouth opening, limited jaw movement, or difficulty opening the mouth fully during dental treatment. This blog explains what mouth opening means, why fixed teeth may be planned in reduced openings, whether natural teeth can be retained, and how treatment planning depends on the available space, back teeth support, and clinical evaluation.

What is Mouth Opening?

It refers to the distance between the upper and lower teeth when the mouth is opened as wide as possible. It is measured from the uppermost point of one tooth to the lowermost point of the adjacent tooth. You can also use a ruler placed between your upper and lower teeth to get an approximate measurement of the opening. The upper teeth are measured from the front edge of the central incisor (the tooth in the middle of the upper lip) to the back edge of the incisal edge of the last molar (the last tooth in the upper jaw). Similarly, the lower teeth are measured from the front edge of the central incisor to the back edge of the incisal edge of the last molar.

Why Fixed Teeth in Reduced Mouth Opening?

This is due to the fact that the mouth opening is not large enough to allow for maximum retention of the replacement teeth. This is particularly so for back teeth. The normal mouth opening for this region is approximately 10 mm but for back teeth, the opening is reduced to 8 mm or less. This is because the back teeth are more movable compared to the front teeth, which are more fixed. Since the back teeth are more movable, they need to be stabilized by a reduced mouth opening to prevent them from moving out of position. Hence, fixed teeth are given in a reduced opening to achieve greater retention.

Can fixed teeth be given in smaller opening?

Yes, fixed teeth can be given in a smaller opening. This is usually done for the incisors (front teeth) and the premolars (upper teeth). For these teeth, the mouth opening is usually the same as the adjacent teeth for better aesthetics.

1. 8 mm or less is ideal. The size of the mouth opening depends on the type of posterior teeth given (i.e. upper or lower teeth). In general, the opening for lower teeth is smaller compared to the upper teeth.
2. Lower fixed teeth – The usual size of the mouth opening is 6 mm.
3. Upper fixed teeth – The usual size of the mouth opening is 10 mm.

Can natural teeth be retained in a reduced opening?

Yes, natural teeth can be retained while giving fixed teeth in a reduced opening. This can be done by reducing the arch length or by increasing the width of the denture teeth. While reducing the arch length of the denture, the upper and lower teeth are brought closer together to reduce the opening. Alternatively, when increasing the width of the denture teeth, the teeth are moved apart, increasing the mouth opening.

For example, for a patient with an upper fixed partial denture with a 10 mm mouth opening, we can reduce the arch length of the denture to 8 mm. This brings the upper teeth closer together and reduces the mouth opening. Alternatively, we can increase the width of the upper denture teeth to 12 mm. This brings the upper teeth apart and increases the mouth opening.

Conclusion

Fixed teeth may be possible even in patients with reduced mouth opening, but the treatment has to be planned carefully. The available mouth opening, missing tooth area, back teeth support, bite condition, natural teeth, and prosthetic space all need to be checked before deciding whether fixed teeth, SAPTeeth, fixed partial dentures, or another option is suitable.

At Royal Dental Clinics, such cases are evaluated through clinical examination, medical history review, and required X-rays or scans. Patients with limited mouth opening should not assume that fixed teeth are impossible, but they should get a proper consultation to understand the safest and most practical treatment plan for their condition.

FAQs

1. Can fixed teeth be given in reduced mouth opening?

Yes, fixed teeth may be possible even when the patient has reduced mouth opening. However, the treatment plan depends on the available space, missing tooth area, bite condition, back teeth support, and overall oral health.

2. What does reduced mouth opening mean?

Reduced mouth opening means the patient is unable to open the mouth fully or comfortably. This can make dental examination, tooth preparation, impressions, scans, and prosthetic placement more challenging, so careful treatment planning is needed.

3. Who may need fixed teeth in reduced mouth opening?

Patients with missing teeth, difficulty chewing, limited jaw movement, restricted mouth opening, or previous oral conditions may need fixed teeth. A dentist must first check whether fixed teeth, SAPTeeth, bridge, denture, or another option is suitable.

4. Can natural teeth be saved while giving fixed teeth?

In some cases, natural teeth can be retained while planning fixed teeth. The decision depends on the condition of existing teeth, gum support, bite, available space, and whether those teeth can safely support the final restoration.

5. Is treatment difficult if mouth opening is small?

Treatment can be more technically challenging when mouth opening is small, especially for back teeth. The dentist may need special planning, modified techniques, smaller instruments, or staged appointments depending on the patient’s comfort and clinical condition.

6. How do I know if fixed teeth are possible in my case?

A consultation is needed to check mouth opening, teeth condition, gums, bite, jaw movement, medical history, and X-rays or scans. After this evaluation, the dentist can explain whether fixed teeth are possible and which option is safest for your case.