2010 RWISO Journal - Roth Williams International Society of ...

Figure 21 Mandibular movement after coronaplasty.
Figure 21-a In the right chewing movement, both the chewing
and the nonchewing sides show sufficient clearance between
the upper and lower posterior teeth (blue arrows).
Figure 21-b In the left chewing movement, both the chewing and
the nonchewing sides show sufficient clearance (blue arrows).
With coronaplasty the patient’s bite was stable, and the
patient was pleased with his smile and with the overall appearance
of his face (Figure 22).
The abnormal tooth wear the patient demonstrated before
coronaplasty was due to improper incisal guidance and
canine guidance. Since tooth wear progresses much faster in
the dentin layer than in enamel, his entire dentition would
have become significantly shorter over the next 10 to 20
years, if no intervention had taken place. The patient’s occlusion
was completed with coronaplasty, and the longevity
and stability of his dentition were greatly enhanced.
Discussion
At the present, the majority of dentists believe that teeth
can successfully compensate for the loss of tissue by migration
and elongation, and that these do not disturb the basic
functions of the masticatory system (mastication, speech,
and swallowing). 19 However, some researchers have argued
that anatomical tooth form plays an important role in the
proper function of the masticatory system. 17,18 Knight and
et al conducted a longitudinal study on 223 orthodontically
treated patients 20 years posttreatment. They found that
there was a strong relationship between incisal and occlusal
tooth wear during the mixed dentition and subsequent
wear of the adult dentition. 20 Tooth wear that occurred during
the mixed dentition in these subjects actually occurred
on the permanent incisors. Even though the malocclusion
was corrected, the loss of tissue due to wear in the previously
affected teeth persisted. Consequently, the patients’
incomplete anterior and canine guidance systems continued
to influence their permanent dentition.
Figure 22 Comparison of the case before and after coronaplasty.
Figure 22-a Full-smile facial photograph taken after
coronaplasty shows that the patient’s smile became
more esthetically pleasing.
Figure 22-b Lateral facial photographs taken
before and after coronaplasty show little change.
With regard to interferences in mandibular movement,
Masatoshi and Masanori studied occlusal factors in relation
to TMD in 146 young adults; they concluded that molarguided
occlusion patterns were associated with a high risk
of TMD. 21 All subjects with TMD had nonchewing interferences
in border excursions and in tooth-dictated excursions.
Without additive coronaplasty to restore the lost volume of
tooth material, complete elimination of interferences may
not be possible, nor may it be possible to maintain the optimal
health of the teeth. 16 As we saw in case 6, the teeth
were too worn down to allow for adequate function, and
the post-orthodontic result was an incomplete occlusion vulnerable
to relapse. The patient’s TMJ symptoms would have
persisted, and the attrition process would have accelerated
once the dentin layer was exposed. Tooth wear that occurred
while the patient was receiving treatment was unavoidable in
this case. Early intervention of malocclusion in mixed denti-
RWISO Journal | September 2010
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