Hi mam..
plaque development is due to poor oral hygiene....
plaque development may leads to gingivitis (inflammation and bleeding from gums)
If you left the plaque development it may cause gingivitis,periodontitis, bone loss leads to tooth mobility,tooth loss....
For third molar issues, you need to take IOPA(x_ray) and based on extent of caries treaent will be decided...
**If the caries extent in to pulp,Root canal yreatment should be done...
**If the caries is superficial and doesnot extent in to pulp,simple filling is enough....
Next Steps
kindly visit nearby dentist for furthur consultation and management...