Part 1

Mark explains the dilemmas and dogmas behind hypodontia management.

Dogma / idea influence opening vs closing

1. Canine guidance

o Dogma: Canine guidance better than  group function

§ Only evidence of negative affects relate to canine inclination, when tucked in = greater muscular activity, seems to relate to degree of freedom in occlusion Sugimoto 2011

o Dogma: Proprioception from canine essential / special

§ Some have considered the proprioception of canines to be essential in the reflex arc of chewing.

§ However the ‘special’ proprioception not been shown to be of consequence.

SR on occlusal schemes: Abduo 2015

· Neither canine vs group function occurs naturally

· Occlusal schemes are dynamic

· Neither scheme pathological or therapeutic

· Crucial factor = degree of freedom in occlusion Sugimoto 2011

2. Implants:

§ Idea / dogma: Implants are ideal prosthesis / without risk

1. Infraposition of implant – vertical growth of adjacent teeth and dentoalveolus, result in relative infaocclusion / position of implant

o Between age of 10-30 = infraposition phenomenon of implants more obvious than 30-40  Schwartz-Arad 2015

o Ideal age of implant placement varies

§ Delay until growth complete to prevent infraposition of implant assessed through serial radiographs

2. Implant problems

o Tooth wear, loss of contact points Papageorgiou 2018 SR

o 5-10% implants fail LONG TERM Pablos 2019

Timing of orthodontic treatment

o Idea / dogma: treat hypodontia patient at the usual age i.e. adolescence with 2 stages

§ In between stages the following can occur: risk of root change, boney changes -most significant is of spaces  are greater than 6mm = likely to require bone augmentation in 60-80% of cases Bertl 2017

o  One should delay to treat in single phase or space closure  Beyer 2005

Literature consistent

§ Nordquist 1975 - Silveira 2016 SR, supporting space closure better aesthetics, periodontal outcomes, and no TMD.

Lay people perception

Prefer space closure Qadri 2016