Endodontics – Orthodontics relation, progress and inter-action

Reviewed by : Dr. Moayyad Alkayyal

To look at the big picture, this review will focus on answering the following questions:

1.Is there an effect on the pulp during tooth movement?

2.Is it possible to move pulp-less teeth?

3.Is it possible to move actively inflamed teeth?

4.Is it safe to move previously traumatized teeth with pulpal involvement? What type of trauma? What type of movement?

5.Is there an increased risk of root resorption with RCT?

To under stand the relation between root canal related lesions and orthodontic teeth movement, the biology of tooth movement must be first understood.

Tooth movement is best described as a result of pressure and tension “theory” in which bone forms in areas of PDL tension and resorbs in compressive areas.

The combination of both processes results in the remodeling needed for tooth movement

Tooth movement is PDL modulated process “does that ring a bill about root canal effect on the modulating PDLs?” 

—In the compressed areas blood pressure increases and some times occlusion of vessels occurs leading to release of osteoclasts (inflammatory macrophages!!)

—Simultaneous bone resorbtion with fibrous (PDL) relive occurs leading to fibroblastic activity at the compressed sites (healing of previous inflammation).

—In the tension areas blood vessels stretches with PDL leading to activation of both osteoplastic and fibroblastic activity. 

Phases of tooth movement:

   1- Initial phase:

       rapid tooth movement within PDL space (.4-.9 mm)

   2- Lag phase:

       formation of hyalinized tissue occurs.

   3- Post lag phase:

       hyalinized tissue removed and more osteoplastic  activity found.

Lets answer our questions now …

Endo Ortho

1.Is there an effect on the pulp during tooth movement?

—In 1974 burnside et al, concluded that alteration of response to stimuli in moving teeth have a direct effect on pulpal metabolism.

—Thus, some odontoplast and other pulpal cells will undergo atrophy during orthodontic teeth movement.

—These changes increases with high forces leading to pulpal damage and necrosis.

—Besides the hyalinization associated with high forces peri-apical lesion are expected to form rapidly.

—Taitor and shalla in 1975 linked between respiratory rate of the pulp and it’s dento-genic activity by a direct relation.

—Hamaersky and colleagues in 1980 used a radio-respirmoetric method to conclude that 27.4% depression in the pulpal respiratory rate of the moving tooth.

—This depression was less in young patients explained by more blood inflow due to open apices “clinical implication!!

—To explore the effect on the nervous system of the pulp Bunner and Johnson in 1982 tested the pulpal responses of moving teeth in different pulpal conditions to conclude that symptoms of reversible and irreversible pulpitis might be present and masked by the discomfort associated with orthodontics.

—In 1996 Derringer et al. tested human teeth to find altered metabolic activity leading to increase formation of reparative dentin (the type triggered by injury) both coronaly and apically

—This would lead to increase chances of pulpal damage and necrosis especially with traumatized or closed apices.

2.Is it possible to move pulp-less teeth?

—Hunter et al. in 1990 and Mah et al in 1996 concluded that RCTed teeth can be moved with no restriction in the type, distance or direction of movement when compared to controlled teeth.

3.Is it possible to move actively inflamed teeth?

—In 1994 Andreasen and Andreasen concluded that due to the inter action between pulpal inflammatory products and the inflammatory process of tooth movement, occurrence of external root resorption increases when actively inflamed tooth is moving.

—They recommended that pulpal treatment must be carried out with only clacium hidroxide filling and that gutta percha can be placed after orthodontic movement is completed.

4.Is it safe to move previously traumatized teeth with pulpal involvement ? What type of trauma ? What type of movement?

—Weckwire et al in 1974 studied 45 patients with 53 ednodontically treated teeth after traumatization to find out no statistically significant difference in response to orthodontic movement between this group and the control groupز

—However, the traumatized group had higher rate of external root resorption.

—Hines et al in 1979. evaluated previously avulsed teeth (group with previous RCT and group with vital pulps).

—When they were orthodontically moved 40% of the total avulsed initially vital pulps (71) were necrotized and needed eventual RCT.

—Thus indicating higher chances of pulpal necrosis with history of avulsion.

—Zachrisson and Jacobsen in 1974 evaluated the response to movement in case of root fracture where fragments were healed and not separated for more than 2 years to found out no significant difference in movement to normal tooth.

—In less than optimal healing time orthodontic movement promoted separation of the fractured pieces.

5.Is there an increased risk of root resorption with RCT??

—There is no evidence that pervious successful RCTed teeth have higher chances of getting root resorption with orthodontic tooth movement provided that all other factors are cleared, Hunter et al in 1990.

Conclusion and clinical implication

1.Light continues forces limit the chances for pulpal damage during orthodontic movement.

2.Endodontically treated teeth can be moved orthodontically.

3.Active pulpal inflammation and history of trauma increases the chance for root resorption during orthodontic treatment.

4.Vital pulps with history of trauma especially avulsion are at higher risk of necrosis during orthodontic movement.

5.A 2 year follow up prior to moving fractured root is recommended.

6.With all other factors being normal RCTed tooth is not subjected to higher root resorption rate. 

References:

1.1974 burnside et al

2.Taitor and shalla in 1975

3.Hamaersky and colleagues in 1980

4.Bunner and Johnson in 1982

5.1996 Derringer et al.

6.1994 Andreasen and Andreasen

7.Zachrisson and Jacobsen in 1974

8.Hunter et al in 1990

9.Am J Orthod Dentofacial Orthop 2016;150:364-77

10.Anhoury PS. Retromolar miniscrew implants for Class III camouflage treatment. J Clin Orthod 2013;47:706-15

11.Poletti L, SilveraAA, Ghislanzoni LT. Dentoalveolar class III treatment using retromolar miniscrew anchorage. Prog Orthod 2013;14:7.

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