In an edentulous patient, jaw relations are recorded without use of face bow. Maxillary cast is mounted on articulator. Now dentist want to increase vertical dimension of occlusion by 4 mm. It leads to?
First, I need to recall the core concepts related to vertical dimension of occlusion in prosthodontics. Vertical dimension of occlusion refers to the vertical distance between the upper and lower jaws when the teeth are in occlusion. Adjusting this can affect various anatomical structures and functions, such as the temporomandibular joint (TMJ), facial aesthetics, and muscle function.
When the vertical dimension is increased, the patient's face might appear longer, and there could be changes in the resting position of the tongue and lips. Also, increasing VDO can lead to increased pressure on the TMJ, which might cause discomfort or pain. Additionally, the muscle activity, particularly the elevator muscles of the mandible, might be affected because they have to work harder to maintain the new vertical position.
Now, the options are not provided, but the correct answer is about the consequences of increasing VDO. Let's think about possible options. Common issues when increasing VDO include TMJ problems, altered phonetics, increased muscle activity, and changes in the airway. Since the question is from a prosthodontics context, the most likely correct answer would relate to TMJ stress or muscle overactivity.
Assuming the correct answer is about increased stress on the TMJ, then the explanation would involve how increasing VDO affects the joint. The TMJ is a synovial joint that allows for hinge and sliding movements. Increasing the vertical dimension can alter the condylar position, leading to increased joint pressure and potential for temporomandibular disorders (TMD). This is a classic point in prosthodontics.
The distractors might include things like decreased muscle activity (incorrect), no effect on TMJ (incorrect), or immediate adaptation (which is less likely). Each of these would be incorrect because the adjustment in VDO does have a direct impact on the TMJ and surrounding muscles.
Clinical pearls here would be that increasing VDO can lead to TMJ issues and that careful monitoring is necessary post-adjustment. Also, patients might experience a longer face appearance, which is a high-yield fact for exams.
**Core Concept**
Vertical dimension of occlusion (VDO) adjustments in edentulous patients affect temporomandibular joint (TMJ) mechanics, facial aesthetics, and neuromuscular adaptation. Increasing VDO elevates the mandible, altering condylar position and joint space, which can lead to TMJ stress or dysfunction.
**Why the Correct Answer is Right**
Increasing VDO by 4 mm without a face bow (which records horizontal jaw relations) may cause **increased TMJ pressure and condylar displacement**. This occurs because the mandible is elevated, reducing the condylar inclination angle and compressing the articular disc, potentially leading to arthralgia or degenerative changes. Additionally, the elevator muscles (masseter, temporalis) may experience hyperactivity due to altered resting posture.
**Why Each Wrong Option is Incorrect**
**Option A:** *Decreased muscle activity* – Incorrect. Increased V