Occlusion PDF

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occlusion...

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Occlusion To occlude means; to stop, to obstruct Basic Concept: Every tooth opposes two teeth in opposing arch except: a. Mandibular CI b. Maxillary 3M Maxillary Arch: Each tooth in maxillary arch opposes two teeth in Mandibular arch except Mx 3M which opposes only 1 tooth. Mnemonic: U—O—D U----- Upper O----- Opposing tooth D----- Tooth distal to it e.g; Mx 1 PM U---upper Mx 1 PM O--- Lower Mn 1PM D--- Lower Mn 2PM (distal to 1PM) Mandibular Arch: Each tooth in mandibular arch opposes tooth opposite to it and tooth mesial to opposite tooth. Exception; Mn CI Mnemonic:

L—O—M

L---Lower arch O--- opposing tooth M--- tooth mesial to opposing tooth

Occluding Position Posterior Teeth; Come in contact Anterior Teeth; Maxillary teeth overlaps mandibular teeth (in normal occlusion) ### Cusps always occludes in areas### Guiding Cusps: ***cusps which guides the occlusion and do not come into contact. ***Do not hold masticatory forces These are; Mn lingual Cusps of posterior teeth Mx Buccal Cusps of posterior teeth

Holding Cusps: ***Cusps which come in contact in opposite arch. ***Holds masticatory forces These are; Mn Buccal Cusps Mx Lingual Cusps Occlusion involves cusps and areas:

Occlusion

Cusps

Guiding Cusps

Areas

Supporting Cusps

1. Slopes 2. Inclines

Mn Lingual

Mx Buccal

Mn Buccal

Mx Lingual

3. Contact Areas 4. Fossas

Areas

Guiding Cusps to center of tooth

Occusal slopes inside of supporting or holding

cusps

Picket Fence: It helps to tell us about the buccal cusps but not the lingual cusps so if we use it along with these tables and rules, we can solve almost any occlusion question….. Step 1: Draw 9 vertical straight lines, 6 lines on equal distance, line # 7,8,9 should be double the distance of first 6 lines.

Step 2: Draw the cusps on these lines these will represent the maxillary teeth

3M

2M

1M

2PM 1PM

C

LI

CI

Step 3: draw lines representing lower teeth. Lower anterior teeth are less wide than upper teeth. A. Mn CI should be drawn from first line to the middle of Mx CI B. Mn LI in the middle of Mx LI C. Draw lines cusps to down except the Mn 1M that line should be distal to the Distobuccal Cusp.

D. Name the lower teeth now.

3M

3M

2M

1M

2M

2PM

1M

1PM

2PM

C

1PM

LI

C

CI

LI

CI

PICKET FENCE It helps to solve questions about buccal cusps for questions about lingual cusps follow the rules below……

Holding Cusps: Maxillary Holding Cusps:

U—O—D

Mx 1PM

Mn 1PM & Mn 2PM

Mx 2PM

Mn 2PM & Mn 1M

Mx 1M

Mn 1M & Mn 2M

Mx 2M

Mn 2M & Mn 3M

Mx 3M

Mn 3M only

Rule for Maxillary PM: DMR of opposing tooth + MMR of tooth distal to it Rule for Mx Molars: Mesiolingual Cusp

Central fossa of opposing tooth

Distolingual Cusp

DMR of opposing tooth + MMR of tooth distal to it Exception Mx 3M distolingual cusp is usually missing……

Mandibular Holding Cusps

L—O—M

Mn 1PM

Mx 1 PM & Mx Canine

Mn 2Pm

Mx 2PM & Mx 1PM

Mn 1M

Mx 1M & Mx 2PM

Mn 2M

Mx 2M & Mx 1M

Mn 3M

Mx 3M & Mn 2M

max Mandibular PMs: Mn 1PM

MMR of Mx 1PM

Mn 2PM

MMR of Mx 2PM

Mandibular Molars: Rule: Mesiobuccal Cusp Distobuccal Cusp

DMRs and MMRs Central fossa

Mesiobuccal Cusp

1M 2M 3M

DMR of Mx 2PM MMR of Mx 1M DMR of Mx 1M MMR of Mx 2M DMR of Mx 2M MMR of Mx 3M

Distobuccal cusp Central fossa of MX 1PM Central fossa of Mx 2M

Distal Cusp Mx 1M triangular fossa Absent

Central fossa of Mx 3M

Absent

M

Guiding Cusps: Maxillary Guiding Cusps: ***Buccal Cusps of Mx PMs and Molars ***Fall in facial embrasure of its counterpart and tooth distal to it e.g; Mx 1PM falls in embrasure between Mn 1PM and Mn 2PM. Maxillary Premolars: Rule: Maxillary premolars occludes the facial embrasures of mandibular teeth Mx 1PM

Facial embrasure between Mn 1PM and Mn 2PM

Mx 2PM

Facial embrasure between Mn 2PM and Mn 1M

Maxillary Molars: Rule: Maxillary guiding cusps of Molars occlude the embrasure or grooves of Mandibular teet

Mx 1M Mx 2M Mx 3M

Mesiobuccal Cusp Meiobuccal groove of Mn 1M Buccal groove of Mn 2m Buccal groove of Mn 3M

Distobuccal Cusp Distobuccal groove of Mn 1M Facial embrasure between Mn 2M & Mn 3M

Mandibular Guiding Cusps: L—O—M Rule: Mandibular Premolars: guiding cusps occlude the lingual embrasure of maxillary teeth Mandibular Molars:

1M 2M 3M

Mesiolingual Cusps

lingual embrasures of maxillary molars

Distolingual Cusps

lingual grooves of maxillary molars

Mesiolingual Cusp Lingual embrasure between Mx 1M and Mx 2PM Lingual embrasure between Mx 2M and Mx 1M Lingual embrasure between Mx 3M and Mx 2M

Distolingual Cusps Lingual groove of Mx 1M Lingual groove of Mx 2M absent...