For a loose complete denture relining and rebasing can be done in which of the following condition:

 # For a loose complete denture relining and rebasing can be done in which of the following condition:

A. Excessive alveolar bone loss 

B. When centric relation and centric occlusion do not coincide 

C. The patient is poor and cannot afford new dentures

D. More than 2 mm loss of alveolar bone height 

The correct answer is C.  The patient is poor and cannot afford new dentures.

Relining and rebasing Indications:

• Immediate dentures at 3 - 6 months after their original construction. 

• When the residual alveolar ridges have resorbed and the adaptation of the denture basis to the ridges is poor. 

• When patient cannot afford the cost of new dentures. 

• Geriatric or chronically ill patients 

• Centric occlusion should coincide with centric relation 

Contraindications: 

• Excessive amount of resorption 

• Abused soft tissues are present 

• Patient complains of temporomandibular joint problems 

• Dentures have poor esthetics 

• Dentures creating speech problems 

• Severe osseus undercuts exist, until surgical removal and healing occur. 

Highest incidence of maxillary extra canal is seen in which tooth:

 # Highest incidence of maxillary extra canal is seen in which tooth:

A. Maxillary first premolar

B. Maxillary first molar

C. Maxillary second molar

D. Mandibular first premolar

The correct answer is B. Maxillary first molar.

The maxillary first molar usually has three roots with a single canal located in each root except with the mesiobuccal root in which a second canal may be present. With the use of magnification devices, the incidence of this canal is as much as >90%. 

Most common variation of tooth in relation to size and mass is common in ______________ teeth.

 # Most common variation of tooth in relation to size and mass is common in ______________ teeth.

A. Mandibular and maxillary premolar

B. Maxillary canine and premolars

C. Mandibular premolar and third molar

D. Maxillary lateral incisor and third molar

The correct answer is D. Maxillary lateral incisor and third molar.

Microdontia most commonly affects maxillary lateral incisors followed by third molars. 

Macrognathia is not a feature of:

 # Macrognathia is not a feature of:

A. Paget’s disease

B. Leontiasis ossea

C. Acromegaly

D. Parry Romberg Syndrome

The correct answer is D. Parry Romberg Syndrome.

Asymmetry of the face is a feature of Rarry-Romberg syndrome. One side of the face shows relative Micrognathia. 

Parry Romberg syndrome: Genetic disorder characterized by atrophic changes of the deeper structures involving one side of the face (e.g., fat, muscle, cartilage & bone) 

Romberg syndrome: Hemifacial atrophy, progressive atrophy of soft tissue of 1/2 inch of face + contralateral Jacksonian epilepsy & trigeminal neuralgia. 

Taurodontism is characterized by:

 # Taurodontism is characterized by:

A. Hypercementosis

B. Elongated wide pulp canals and short roots

C. Obliterated pulp chambers with secondary dentin deposition

D. Rootless teeth with thin shell of enamel

The correct answer is B. Elongated wide pulp canals and short roots.

Taurodontism (Bull Teeth) is due to failure of hertwig's sheath to invaginate at the proper horizontal level. Mostly molars are involved and the body of tooth is enlarged at expense of roots resulting in rectangular teeth. The roots are short and the pulp chambers are extremely large lacking the usual constriction at cervix of tooth. It has been reported that many patients with Klinefelter syndrome exhibit taurodontism but is not constant feauture of this syndrome.

Developmental enamel defects are most commonly seen in:

 # Developmental enamel defects are most commonly seen in:

A. Primary incisors

B. Primary second molar

C. Permanent incisors

D. Permanent first molar

The correct answer is C. Permanent incisors. 

Clinical studies indicate that most cases of enamel hypoplasia involve those teeth that form within the first year of birth, mainly the central and lateral incisors, cuspids, and first molars. 

• Amelogenesis imperfecta: All teeth of both dentitions are affected to some degree. In some cases, the teeth may appear essentially normal. 

• Hypoplasia due to nutritional deficiency and exanthematous fevers: The teeth most frequently involved are central & lateral incisors, cuspids, and first molars. 

• Enamel hypoplasia due to congenital syphilis: Maxillary & mandibular permanent incisors & the first molars are involved. 

• Enamel Hypoplasia due to local infection or trauma: Most commonly one of the permanent maxillary incisors or a maxillary or mandibular premolar is involved. 

Most commonly submerged tooth is:

 # Most commonly submerged tooth is:

A. Mandibular primary first molar

B. Mandibular primary second molar

C. Maxillary primary first molar

D. Maxillary primary second molar

The correct answer is B. Mandibular primary second molar. 

‘Submerged’ teeth are deciduous teeth, most commonly mandibular second molars, that have undergone a variable degree of root resorption and then have become ankylosed to the bone. This process prevents their exfoliation and subsequent replacement by permanent teeth. After the adjacent permanent teeth have erupted, the ankylosed tooth appears to have submerged below the level of occlusion. This illusion is explained by the fact that there has been continued growth of the alveolar process and also that the crown height of the deciduous tooth is less than that of the adjacent permanent teeth, so that the relative level of occlusion has been changed, not the position of the deciduous tooth. 

The mandibular primary molars are the teeth most often observed to be ankylosed. In unusual cases all the primary molars may become firmly attached to the alveolar bone before their normal exfoliation time.