Abstract
Horizontally impacted mandibular molars are not uncommon. However, we report a rare case of a horizontally impacted stacked second and third mandibular molar. This paper presents adaption of the principles of surgical exodontia to account for rare variations in abnormal anatomy and a review of the literature, weighing up the balance between orthodontic intervention and surgical removal. Successful removal depends on careful surgical planning and respect for the surrounding anatomical structures whilst following the principles of surgical exodontia.
Clinical relevance:
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This paper highlights the surgical considerations that should be taken into account for treatment planning of anatomically abnormal exodontia cases.
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We revisit the principles in removing horizontally impacted wisdom teeth in general practice and/or secondary care.
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We outline the potential complications encountered when removing such teeth.
Objectives
The reader should understand the principles of surgical exodontia of horizontally impacted lower molar teeth.
1
Background
Impaction of mandibular second molars (M2M) is relatively rare, carrying an incidence of 0–2.3 % [ ]. However, deep horizontal impaction prevention eruption, and associated arrest eruption of the mandibular third molar (M3M), is even rarer [ , ]. In such cases, there is a greater likelihood jeopardization of adjacent normal structures, aesthetic compromised and reduction of masticatory abilities.
Eruption of M2M, involves the mesially inclined tooth bud (in relation to the first molar), being corrected by the remodelling of the ramus [ ]. Failure of this can lead to malocclusion, including failure of eruption, due to impaction on the adjacent first molar. Archer (1975) described an impacted tooth is one which is unable to completely erupt as it is positioned against another tooth, bone, or soft tissue, meaning further eruption is unlikely [ ]. Based on this impaction can be described as against soft tissue, partial or complete bony impaction. Impaction can be further defined by the tooth’s location in relation to the surround structures. These classifications, although first applied to M3M, aim to provide guidance on predicting the surgical difficulty of removal. Winter’s (1926) classification considers the horizontal inclination of the third molar in relation to the long axis on the second molar, as well as Pell and Gregory’s (1933) which uses the vertical position of the third molar in relation to the ramus and second molar [ , ].
Furthermore, positioning of the impacted tooth can also provide the clinician with an indicator of risk of pathology. For example, multiple studies have shown that mesio-angulated M3M carry the risk of development of caries in M2Ms, which increases with age [ , ]. Whereas disto-angulated M3M, have the highest association in comparison to other inclinations, which pericoronitis [ ]. Full or partial retention of unerupted molars can also lead to other pathologies such as cyst or tumour formation [ ].
However, removal of impacted mandibular molars to eliminate the risk of developing these associate pathologies, also carry it’s own risks. The most significant and debilitating of which, is injury to the inferior alveolar nerve, which lead to the development of trigeminal sensory neuropathies, and in turn chronic pain [ ].
1.1
Case presentation
A 22-year-old female patient was referred to the Oral and Maxillofacial department at Russell’s hospital, Dudley, for management of recurrent pain, food impaction and pericoronitis. The patient’s symptoms stemmed from an impacted lower right second and third molar, found by their general dental practitioner (GDP). Medically, the patient’s history was unremarkable, with no known drug allergies and in terms of her social history, drank approximately 6 units per week of alcohol and never smoked.
On clinical examination, it was noted that moderate inflammation and tenderness surrounded the LR8, and the LR7 was clinically not visible. The LL8 in addition, was partially erupted and the LR7 vertically impacted. The OPG ( Fig. 1 ) confirmed the presence and location of the LR7 to be inferior to the horizontally impacted LR8. The LR7 was also horizontally impacted, according to Winter, the mesial cusps at the level of the cemento-enamel junction of the LR6 (Class 3 according to Pell and Gregory, 1933). Furthermore, the resorption of both lower 6 distal roots and relatively in close proximity of the lower 8’s to the inferior dental alveolar nerve. A cone beam CT scan was performed ( Fig. 2 ) to further evaluate root morphology in relation to vital structures.
1.2
Surgical technique
Extraction of both the third and second molar was planned to avoid any further potential damage to the adjacent first molar. This treatment was performed under general anaesthetic. Local anaesthetic was administered as inferior dental alveolar block and long buccal infiltrations. A more extensive two-side full thickness mucoperiosteal flap was raised from the LR8 to the LR5, with distal relieving incision, to again adequate access and visualisation of the LR7 impaction.
Delivery of the LR8 was naturally approached first, by creation of a buccal gutter with a small amount of bone removal distal of the LR8 with a fissure burr. This was followed by vertical sectioning (decoronation) of the LR8 into two parts to enable removal. In order to extract the LR7 extension of the buccal gutter was required. A rose head burr, which provides the operator with more control over the depth of drilling, was used due to the closer proximity to the IDN. Finally, the LR7 was decoronated to relieve the impaction and allow the root to be spilt in the long axis and elevated out, using a fissure burr (see Figs. 3–6 ).
