Difficult access Cavity Preparations

The areas where I find it the most difficult to access for cavity preparation are the lingual of the lower molars and the buccal of the upper molars. This is due to the associated structures of the tongue and cheek respectively. Some patient's are easier to work on than others in these areas. you will find that the patients with more weight under the belt will have increased tongue size due to an increase in tongue fat volume. I have already made a post about working in the lingual area:

http://dental-tidbits.blogspot.com/2020/01/lingual-isolation.html

The buccal area of the upper 7s and 8s often become carious for the same reason that they are difficult to treat: difficult access for cleaning:

http://dental-tidbits.blogspot.com/2019/01/plaque-accumulation-on-7s.html

Plaque accumulation occurs on these surfaces and the proximity of the cheek traps food particles against this plaque leading to rapidly processing, wide areas of decay. This is why upper 8s are often caved in on the buccal aspect. In a young person this is a sign of a high sugar grazing diet.

The most reliable way I have found to restore these areas are as follows:
-Position the patient with their mouth half closed, your dental assistant can position the suction tip before they do this and the patient can actually bite down on the suction to maximise the possible closure. Additionally, they can swing their mandible towards the side you are prepping. This maximises the horizontal dimensions you can retract the cheek and moves the coronoid process from the site,
-Use dry tips to protect the cheek. Use a slightly smaller size than will fit as if you use a larger size it will be too wide and will clash with the vestibule and bunch up. place the dry tip more maxillary than mandibular to be centered over the tooth in question. It is easier to retract the cheek this way because your mirror pressing at one spot on the dry tip will push the whole dry tip away from the tooth.
-Use a massive bur. If there is enamel present, use the largest diamond round bur or football bur that will fit within the occlusogingival dimension of the prep. If the enamel is already cavitated in an area, the entire prep can be done with a large slow speed round bur. The idea is to use the bur parallel to the long axis of the tooth so the handpiece can fit snugly in the available area.

Using the handpiece in the long axis of the tooth allows it to fit into the narrow space against the cheek. 

Holding it perpendicular to the tooth stretches the mucosa and reduces your control

The trick is to use the shank of the bur as a non cutting area to control the depth of the bur. The largest possible bur is required to cut deep enough to clear the caries. Sweep the bur mesiodistally keeping the shank against the sound enamel margin until the caries is cleared. When you have gone deep enough into the cavity preparation you should be able to slip the bur subgingivally if the caries extends there