Dentosphere : World of Dentistry

Best retainer for midline diastema

# In case of orthodontically treated midline diastema which retainer should be used?

A. No need for retainer

B. Hawley appliance for 6 months

C. Lingual bonded retainer

D. Hawley appliance for 12 months

The correct answer is C. Lingual bonded retainer.

Fixed (bonded) orthodontic retainers are normally used in situations where intra-arch instability is anticipated and prolonged retention is planned.

There are four major indications:

- Maintenance of lower incisor position during late growth

- Diastema closure maintenance

- Maintenance of pontic or implant space

- Keeping extraction spaces closed in adults

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Best investment for casting base metal crowns is:

# Best investment for casting base metal crowns is:

A. Phosphate bonded investment

B. Gypsum bonded investment

C. Ethyl silicate

D. High grade silicate bonded

The correct answer is: A. Phosphate bonded investment.

Gypsum bonded investments are used for casting gold alloys. These can withstand a temperature of 700 degree C.

Base metal alloys, high melting gold alloys, which are used for metal ceramic restorations, are invested by phosphate bonded investments.

Silica bonded investments are an alternative to the phosphate bonded investments, for high temperature casting. They are used in the casting of base metal alloy partial dentures.

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Stages of Anesthesia

The different stages of anesthesia are:

Stage I: Analgesia and conscious sedation

Stage II: Stage of delirium

Stage III: Stage of Surgical Anesthesia

Plane I: Pupils dilate progressively with the depth of anesthesia. Lid reflex, swallowing, retching and vomitting gets abolished. Corneal reflex is present. Conjunctival reflex is absent. Pharyngeal reflex is lost.

Plane II: Eye balls fixed, laryngeal reflexes are also abolished.

Plane III: Asynchrony between thoracic and abdominal movements. Progressive paralysis of intercostal muscles, Pupillary light reflex and corneal reflex are lost.

Plane IV: Complete intercostal muscle paralysis. Pupils are dilated. Muscles are flaccid.

Stage IV: Stage of respiratory paralysis

Minor surgeries like dental extractions are carried out in stage I or stage of analgesia. Major surgeries are carried out on Plane III of Stage III of General Anesthesia or the stage of Surgical Anesthesia.

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