Introduction
The routine surgical removal of asymptomatic third molars has almost
become a rite of passage in many countries. On the other hand, alignment
of the remaining dentition has been addressed with special emphasis on
the ‘social six’ upper anterior teeth [1]. The reasons for these
trends are varied and complex but likely have an historical basis since
medical complications emanating from partially-erupted and/or impacted
third molars were first reported over century ago [2]. In fact,
impacted third molars have a prevalence of approx. 18-32% in modern
humans, which makes assessment of their eruptive prognosis mandatory
[3] because of complications associated with them. Recently,
Malanchuk et al. [4] confirmed local pathologic processes, which
precede caries as well as inflammation of the soft tissues and the
adjacent alveolar bone, to justify surgical attenuation of the (lower)
third molars. A systematic review [5] had also reported that
pathologies related to third molar retention include caries, periodontal
diseases, second molar root resorption, and pericoronitis. In addition,
Cederhag et al. [6] evaluated the anatomic relations of the lower
third molars with respect to the inferior alveolar nerve using panoramic
radiographs. They reported that their roots were located above the
inferior alveolar nerve in about half (52%) of the cases examined.
However, while panoramic radiography is extensively used for diagnosis
and preoperative treatment planning, the predictive value of this data
remains ambiguous. In this regard, Vranckx et al. [7] assessed
radiologic risk indicators and postoperative morbidity in patients
undergoing upper and/or lower third molar exodontia. They noted that
severe impactions were associated with postoperative pain, trismus and
swelling with a need for pain medication. However, when the ability to
identify the risk of third molar non-eruption using panoramic
radiographic analysis was evaluated, Libdy et al. [8] found that
both orthodontists and oral maxillofacial surgeons were unable to
predict which third molars would become impacted; both groups of
specialists indicated extractions in approx. 50% of cases, being unable
to distinguish those in which the third molars would erupt normally.
To prevent future dental pathology of adjacent teeth, the prophylactic
extraction of asymptomatic third molars is commonly advocated. However,
in a series of three cases [9] periodontal attachment loss and
serious damage of the adjoining second molar was reported, while a third
patient suffered post-operative osteomyelitis and fracture of the angle
of the mandible during prophylactic exodontia. In addition, the
extraction procedure is sometimes associated with damage of the inferior
alveolar nerve when the tooth roots are anatomically adjacent to it,
resulting in sensory dysfunction, such as paresthesia. Repass [10]
was one of the first to describe the inferior dental nerves passing
through the roots of impacted mandibular third molars. Furthermore,
mandibular fractures are also a relatively common risk and represent a
serious post-operative complication. Beret et al. [11] evaluated
mandibular fracture complications of impacted lower third molars, which
included post-operative malocclusion, mouth opening limitation, inferior
alveolar nerve paresthesia, infection, delayed bony union, and loosening
of surgically-placed hardware. To avoid the risks of post-operative
morbidity and injury, coronectomy has become more common. However, one
of the sequelae of coronectomy is eruption of the retained root, and
Steinberg et al. [12] described a case in which the retained root
displaced the inferior alveolar nerve, resulting in neurologic symptoms.
Thus, as unerupted third molars rarely remain pathology-free, new
approaches are needed to address their clinical management. Therefore,
the aim of this study is to describe a series of cases treated by a
general dentist using the DNA appliance (Vivos Therapeutics, Inc., USA)
that putatively increases midfacial bone volume [13] as an
alternative technique in the clinical management of unerupted third
molars.