Wisdom Tooth Wisdom Demystifying the Past And Planning for the Future Ted Fields, DDS, PhD
Course Outline Part I: To Remove or Not to Remove 1. Development 2. Wisdom teeth as an asset 3. Wisdom teeth as a liability 4. Alternatives to removal 5. Timing of removal
Course Outline Part II: Treatment Approach • Assessing the difficulty of removal • Patient counseling and preparation • Anesthesia • Instrumentation • Technique
Course Outline Part III: Management of Infected Teeth
Course Outline Part IV: It Ain’t Over Till It’s Over • Complications • Post-operative care • Documentation
The Difficulty in Understanding 3rd Molars • European third molar surgery is much different than that in the U.S. • Lingual fracture technique • Different instrumentation • Different economic influences on dental care
The Difficulty in Understanding 3rd Molars 2. Many research papers of the past 20 years set out to prove or disprove old ideas – many of which themselves are outdated. • Will the 3rd molar erupt? • Is there enough arch length for eruption? • Does removal of the 3rd molar compromise the 2nd molar?
The Difficulty in Understanding 3rd Molars • Much of the developmental literature is written from an orthodontic viewpoint. • There is an outcome bias towards younger individuals (what is the result in a 16-yr-old?) • The 3rd molar is judged in relation to orthodontic needs, rather than the patient’s overall needs.
The Difficulty in Understanding 3rd Molars 4. Many changes in technology have been totally neglected. • Implants • Electric handpieces • Antibiotics • Hemostatic agents • Bone augmentation materials
The Difficulty in Understanding 3rd Molars • The topic is not covered in any depth in most dental schools. • Knowing when it is in the patient’s best interest to remove 3rd molars is a judgment that requires detailed knowledge of the risks and benefits associated with tooth retention and with tooth removal.
Initial calcification • Occurs as early as 7yrs, more typically age 9.
Crown Mineralization • Usually completed by age 12 to 14.
Root Formation • Usually half-formed by age 16.
Root Completion • Fully formed roots with open apices are usually present by age 18.
Eruption • Most teeth that will erupt are erupted by age 20. • 95% of all teeth that will erupt are erupted by age 24. • A limited number of third molars appear to erupt, at least to some degree, in young adults.
Predicting Eruption – Who Cares? • Does it matter if a wisdom tooth erupts? • Does it matter when a wisdom tooth erupts?
The Key Issue Does it affect the Risk:Benefit Ratio?
Evaluating Risk:Benefit • Since “Risk of retention” and “Benefit of removal” are essentially the same concept, these terms may be combined. • Since “Benefit of retention” essentially = 0, the equation may be simplified:
Evaluating Risk:Benefit You must consider 2 separate assets of each risk and each benefit: • Magnitude of risk or benefit • Probability of risk or benefit
Magnitude • Is it major or minor? • Does it require hospitalization? • Is it permanent? • Does it affect your daily routine? If so, for how long?
Probability • The most overlooked aspect of most consultations. • Fortunately most real bad outcomes are real uncommon • What is the likelihood of certain problems? How much does treatment alter this likelihood?
The Difficulty of Accurate Risk:Benefit Assessment • The literature is not very complete or very helpful. Complication rates vary widely. Different people view these complications very differently (complication doesn’t always equal perception of the complication) Ogden GR, Bissias E, Ruta DA, Ogston S: Quality of life following third molar removal: a patient versus professional perspective. Br Dent J 1998;185:407410.
The Difficulty of Accurate Risk:Benefit Assessment 2. The wide variety of different complications and the wide range in the incidences of each potential complication result in a complex body of data to assimilate.
Risk:Benefit • Are erupted 3rds more or less subject to disease? • Are erupted 3rds more or less beneficial?
What Impacts Treatment? • Eruption into occlusion should not be the sole criterion of usefulness. • The issue is not “can you save it” but “should you save it.”
Benefits of 3rds • “Functional occlusion” – what is this? • Is it any different than just “occlusion”? • Is all occlusion functional? • Is all functional occlusion important? If so, is it all equally important? • Without evaluating questions such as these, how can you determine the true benefit of 3rds?
Benefits of 3rds – Part II • Orthodontic repositioning to replace missing or grossly compromised 1st molars • Transplantation – poor long-term survival • With dental implants, these are rarely reasonable treatment alternatives.
Tooth Transplantation • Under ideal conditions, 27 oral surgeons transplanted 291 teeth: • 5-yr survival rate: 76.2% • 10-yr survival rate 59.6% Schwartz O, Bergman P, Klausen B: Resorption of autotransplanted teeth. A retrospective study of 291 transplantations over a period of 25 years. Int J Oral Surg 1985;14:245-258.
Conclusion • 3rd molars provide no proven functional benefit and no obvious esthetic benefit. • Rarely, they may provide a treatment option that, at best, is third-line treatment.
What Impacts Treatment? • Failure of eruption should not be the sole criterion for removal. • Successful eruption should not be the sole criterion for retention. • Eruption is not always a “yes” or “no” proposition.
Problem #1 – Soft Tissue • Even with adequate arch length and full eruption, 3rd molars are often surrounded by thin, unkeratinized, highly distensible lining mucosa of the buccal vestibule. • Encourages pathogenic bacteria retention • Poorly withstands hygiene measures
Problem #2 – Periodontal Compromise • Bone loss distal to the 2rd molar after removal of the 3rd molar is controversial, at best. Even with some loss of bone, the result is stable and cleansable – the goal of periodontal therapy.
Bone Loss Distalto the 2nd Molar • A reduction in pocket depth with no change in bone height on the distal of the 2nd molar. Szmyd and Hester Groves and Moore Grondahl and Lekholm
Bone Loss Distalto the 2nd Molar • Alveolar bone crest healing distal to the 2nd molar is enhanced in younger patients with incompletely developed 3rd molar roots. Ash, Costich, and Hayward Ziegler
Augmentation with Freeze-Dried Bone or Bone Substitutes • Why? • There is no independent evidence of benefit • Why graft a contaminated site? • Why graft a site you can’t close primarily? • Your goal is to maintain bone height on the distal of the 2nd molar without pocket formation, not to augment potential defects more posteriorly.
Augmentation: Conclusion • It won’t improve your outcome. • It will undoubtedly increase your infection rate • Why would you want to augment this area anyway?
Problem #2 – Periodontal Compromise • The role of pathogenic bacteria retention in 3rd molar pockets is unknown. How does this affect the rest of the dentition? • Hygenic compromise of the 2nd molar can result in a difficult to restore situation if this tooth is lost.