Combination syndrome
Combination syndrome
Combination syndrome (CS) is a dental condition that is commonly seen in patients with a completely edentulous maxilla and partially edentulous mandible with preserved anterior teeth. This syndrome consists of severe anterior maxillary resorption combined with hypertrophic and atrophic changes in different quadrants of maxilla and mandible. This makes it a challenging condition in dentistry that requires significant experience along with advanced restorative and surgical skills .
combination syndrome also is “The characteristic features that occur when an edentulous maxilla is opposed by natural mandibular anterior teeth, including loss of bone from the anterior portion of
the maxillary ridge, overgrowth of the tuberosities, papillary
hyperplasia of the hard palatal mucosa, extrusion of mandibular
anterior teeth, and loss of alveolar bone and ridge height beneath
the mandibular removable partial denture bases,” also called
anterior hyperfunction syndrome. Kelly was the first person to
apply the term combination syndrome.
Additional changes occurring in clinical situations with
the completely edentulous maxilla and partially edentulous
mandible with only anterior teeth remaining include loss of
occlusal vertical dimension, occlusal plane discrepancy, anterior
spatial repositioning of the mandible, and poor adaptation of the
prosthesis, epulis fi ssuratum and periodontal changes.
Combination syndrome occurs among 25% of individuals
who wear both complete denture opposing mandibular anterior
teeth and a bilateral distal extension removable partial denture
Sequelae of Combination Syndrome
Early loss of bone from the posterior part of the mandible
leads to increase in function in the anterior region as a result of
posterior hypofunction. Hypertrophy of the anterior mandible
with anterior hyperfunction develops. Forces originating from
the lower anterior teeth are directed toward the anterior portion
of the unsupported maxillary denture leading to loss of bone
and ridge height anteriorly, the posterior residual ridge becomes
larger with the development of enlarged tuberosity.
However, enlarged tuberosities are also seen in situations
where mandibular molars have been lost, the opposing
maxillary molars may supraerupt together with the alveolar
process.
Enlarged tuberosities along with an increase in bone
height causes the occlusal plane to migrate up in the maxillary
anterior region and down in the maxillary posterior region,
eventually the natural anterior mandibular teeth migrate upward
with simultaneous mandibular alveolar hypertrophy. Anterior
teeth on the complete denture disappear under patients lip
eff ecting the aesthetic, showing none of the maxillary anterior
teeth and too much of the lower natural anterior teeth.
With the lack of posterior palatal seal, a negative pressure
develops leading to papillary hyperplasia.Along with
negative pressure, chronic occlusal trauma from incisal edges of
mandibular anterior teeth causes fl abby tissues in the anterior
palate termed as papillary hyperplasia. Contradictory fi ndings
have been reported by Kelly and Uçtasli et al.,. while the
former has demonstrated resorption in the edentulous maxilla
with no resorption in the distal edentulous area of the mandible,
its vice versa is true in case of the latter, especially in distal
extensions retained by anterior bar.
Another paramount aspect of the combination syndrome as
a repercussion of ridge resorption is impairment in established
posterior occlusal contact leading to the progressive collapse
of vertical dimension of occlusion causing the mandible to move
forward resulting in pseudomandibular prognathism. The Bone
resorption beneath the mandibular distal extension, wearing
of artifi cial teeth, positional changes in anterior teeth instigate
parafunctional activities, thereby augmenting the force per unit
area on the maxillary alveolar bone
Management of Combination Syndrome
Ill-fi tting dentures have been blamed for all of the lesions of
edentulous tissues, but the most perfect denture will be ill fi tting
after bone is lost from the anterior part of the ridge. Removable
dentures need periodic attention to check for any tissue changes.
Frequent relining of ill-fi tting dentures slows down but does not
stop the development of combination syndrome.
Preventing the degenerative changes that complete maxillary
denture opposing Kennedy’s Class I partial dentures can be best
accomplished by avoiding extraction of lower anterior teeth
and retaining weak posterior teeth as abutments by means of
endodontic and periodontic technique.Also over denture can
be considered as a treatment option of retaining the roots of
anterior mandibular teeth to support an overdenture.
According to Langer et al.
both well designed removable
partial dentures and over denture can be suggested for patients
with an edentulous maxilla and some remaining anterior
mandibular teeth. Well-designed mandibular removable partial
denture is suggested for low-risk patients who have not developed
combination syndrome and whose mandibular anterior teeth
are well preserved and have not supraerupted. However, the
restoration of the posterior occlusion with removable partial
denture will not entirely delay a progressing combination
syndrome. The removable partial denture is advocated for
situations that may eventually develop combination syndrome,
but nevertheless have shown stable occlusion. In the past because
of limitations of removable partial denture a more predictable
outcome can be expected by use of over denture, especially for
patients who already have combination syndrome or whose
mandibular anterior teeth are structurally or periodontally
compromised. Additional retention for mandible may be
provided by stud attachment. Patients elapsed dental history,
and the predicament of the remaining lower anteriors helps in the
appraisal of an individual’s fortuity of developing combination
syndrome.
Apportion of mechanical forces over the larger basal seat
area along with minimal displacement over its basal seat area can
obviate bony resorption. Commodious coverage of basal seat
area by complete denture or removable partial denture, thereby
prorating the forces per unit area is elemental to abate ridge
resorption and preclude combination syndrome.
Covering
the retromolar pad and the buccal shelf with a denture base
retards bone loss.
The destructive changes on the soft tissues brought about
by Class I mandibular removable partial dentures constitutes
a strong support for “shortened dental arch” concept.
Dentures with only anterior and premolar teeth can meet oral
functional demands in most situations.Surgical options can
be considered in treating undesirable conditions associated
with combination syndrome.
The fl abby hyperplastic tissue
can be surgically removed, the papillary hyperplasia can be
eliminated and enlarged tuberosities can be reduced, which
allows the distal end of occlusal plane to be raised to proper
level and allows the lower partial denture bases to be fully
extended over the retromolar pad. Correction of premaxillary
bone atrophy with bone grafting can be successful in treating
combination syndrome.
Traditional occlusal schemes and posterior occlusal forms
incorporate a vertical overlap of anterior teeth. Over time, this
overlap results in anterior contact or hyperfunction due to the
forward and upward movement of the mandible leading to
bone loss caused by the anterior hyperfunction syndrome. An
alternative option to prevent contact of anterior teeth involves
noninterceptive linear occlusion combined with the bilateral
fulcrum of protrusive stability. Linear occlusion consists of
masticatory surfaces in the form of a straight, long occlusal ridge
in contact with fl at monoplane opposing surfaces, there are no
cusp inclines with which to make contact during the envelope
of function. For this reason, linear occlusion is defi ned as a non
interceptive type of occlusion requiring minimal interocclusal
rest space.
Establishing the horizontal plane of occlusion from the
incisal edge of the maxillary central incisors to the top of
retromolar papilla on either side in the posterior region is an
integral part of the linear concept of occlusion.
Guidelines for
linear occlusion includes use of an alternative tooth form with its
inherent absence of anterior vertical overlap. There is no need
for the traditional 2-3 mm interocclusal rest space which does not
mean interocclusal clearance is not needed but less is required.
For this reason, the centric relation record was made at vertical
dimension of rest, allowing teeth to be arranged at a vertical
height that reduced vertical overlap of anterior teeth, 0.020 of an
inch of vertical clearance was provided during the arrangement
of the anterior teeth.
Both implants retained and implant supported prostheses
have become increasing popular and have been proven
successful in prosthetic rehabilitation of partially and completely
edentulous maxilla and mandible.The unstable occlusion
in combination syndrome results in progressive posterior
mandibular atrophy. Use of a conventional denture in restoring
the mandibular dentition provides the least patient satisfaction
as compared with the fi xed prostheses.For this reason, the
patient usually elects to have mandibular rehabilitation with
implant retained prosthesis.
A fixed implant-supported prosthesis of the same design
produced bone apposition in the posterior parts of the mandible,
whereas an overdenture supported by two implants resulted in a
continuous resorption of the same areas.A well-documented
long-term results were found in fi xed mandibular prostheses
supported by implants placed between the mental foramina and
opposing maxillary complete dentures. A study has shown
that in patients who received mandibular implant-supported
fi xed prostheses bone resorption in the posterior part of the
mandible ceased .
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