an alternative method to treat a case with a severe maxillary
TRANSCRIPT
An alternative method to treat a case with a severe maxillary atrophy by the
use of tilted implants and a removable overdenture, instead of complicated
augmentation procedures: a case report
H.Bilhan*, M. Ateş**
* Dr.med.dent., Istanbul University, Faculty of Dentistry, Department of Removable
Prosthodontics, 2nd floor, 34390 Capa-Istanbul, Turkey
** Prof. Dr. med.dent., Istanbul University, Faculty of Dentistry, Department of Removable
Prosthodontics, 2nd floor, 34390 Capa-Istanbul, Turkey
Corespondence address:
Dr. med.dent. Hakan Bilhan, Istanbul University, Faculty of Dentistry, Department of
Removable Prosthodontics, 2nd floor, 34390 Capa-Istanbul, Turkey
Fax: +90-212-525 35 85
e-mail: [email protected]
Prof.Dr. Muzaffer Ateş Dr. Hakan Bilhan
An alternative method to treat a case with a severe maxillary
atrophy by the use of tilted implants and a removable
overdenture, instead of complicated augmentation procedures: a
case report
Abstract
Background: Several treatment options with implants have been described
for maxillary edentulous patients. Maxillary implant-supported overdentures
have been shown to be a predictable, accepted treatment option for the
edentulous maxilla. Patients with severe bone resorption present additional
difficulties and implant treatment in the atrophic maxilla represents a
challenge. Methods: Anatomical limitations and patient desires in this case
has forced the treatment to be four tilted implants supporting an upper
overdenture. Since conventional single retention mechanisms such as ball
(O-ring), locator or telescopes would transfer too much force to the
implants, especially due to their angulation, an individual bar was
fabricated. Results: One year follow-up of the case showed a stable
periimplant condition on bone as well as soft tissue level.
Conclusions: Although further follow-up and higher case numbers will give
more information about this treatment modality, the actual result is
encouraging and can be recommended for similar cases.
Key Words: Tilted implants, severely atrophied maxilla, individual bar,
implant overdenture, Marius Bridge
Introduction
Several treatment options with implants have been described for
maxillary edentulous patients. 1, 2, 3, 4, 5 Maxillary implant-supported
overdentures have been shown to be a predictable, accepted treatment
option for the edentulous maxilla. 6, 7
Patients with moderate to severe bone resorption and thin ridges
present additional difficulties because of inadequate bone volume and
missing soft-tissue support, thus due to mechanical and anatomic
drawbacks, implant treatment in the atrophic maxilla represents a
challenge. The maxillary sinus floor augmentation procedure is still not
universally accepted because of its complexity and its unpredictability.
Additionally, patients showing that kind of maxillary resorption are
generally very old and poor in their health status. Serious and complex
surgical procedures could be contraindicated in these patients.
Results of investigative studies indicate that the use of tilted
implants is an effective and safe alternative to maxillary sinus floor
augmentation procedures, 8 because longer implants can be inserted in
this way. The use of reduced-diameter implants as an alternative to bone
grafting for treatment of patients with severely resorbed maxillae was
evaluated.9 As a conclusion implant anchorage without bone grafting was
shown to work well, alhough it is expected that patients with severely
resorbed maxillae have an increased risk of implant failure in comparison
to patients with good bone quantity and quality. In another study with
patients having severely resorbed maxillae bone grafting and implant
placement was compared to modified implant placement but no bone
grafting. The cumulative success rates were 83% in the graft group and
96% in the trial group and a substantial reduction of the grafted bone,
especially of the onlay grafts, occurred in many patients.10 According to
these results, modified implant placement, in our case tilted implant
positioning to be able to use longer implants, seems to be a predictable
therapy alternative.
Case Description and Results
A 63-year old female edentulous patient applied to the Department
of Removable Dentures in the Dental School of Istanbul University with
the complaint of not being able to use any dentures because of strong
choke reflex. It was obvious that the only choice of treatment could be a
denture without palatal coverage. Clinical and radiological assessment
showed a severely atrophied maxilla, with bilateral large sinuses and very
little amount of bone, making a conventional implant planning impossible.
After information and discussion about treatment alternatives, the patient
rejected the sinus floor or any other augmentation procedures. The only
bone available for implantation was in the region of the premaxilla and
tuber maxilla and even there limited in height.
An overdenture attached to four implants and open palatal surface
was planned. Because of lacking bone height, all four Astratech implants
with a TiO-blast surface were inserted in a tilted manner. Two implants
were inserted in the premaxillary region and one each in the tuber maxillae
region bilaterally (figure 1). Implant number 22 was lost after 2 months and
substituted with a new implant following a 6 week healing time (figure 2).
This loss caused a delay of the prosthetic treatment. 8 months after the first
implant insertion the first impressions were taken. Because of the various
implant angulations, an open individualized tray was used for the
impression of the upper jaw. The impression tray borders were moulded
with functional silicone (Bisico Fuction, Germany) and the final impression
was taken with a high viscosity poliether impression material (Impregum
soft, Germany). Before removing the impression from the mouth, by
opening the screws of the transfer posts, the open parts of the tray were
strenghtened by the use of a pattern resin (GC Pattern Resin, America) in
order to avoid even a slight movement of the posts, which would make the
model useless. Then the impression of the lower jaw was taken first with
alginate and then with a custom tray by border moulding and ZnO Eugenol
paste. After wax rim try-in, determination of vertical dimension and centric
relation, a facebow recording was done. The tooth setup was done on the
articulator and then controlled in the patient. After correction of esthetic and
functional determinants, the planning of the attachment system could be
done. Since we were convinced that conventional single retention
mechanisms such as ball (O-ring), locator or telescopes would transfer too
much force to the implants, especially due to their angulation, an individual
bar was fabricated. In this manner, the force applied for removal of the
denture was shared by the implants (figure 3).
The bar try-in was passive and well-fitting (figure 4), so the denture
was finished and delivered to the patient (figure 5 & 6). The patient was
very satisfied with the result.
The follow-up controls in the 6th (figure 7) and 12th months (figure 8)
after denture insertion showed clinically and radiologically in comparison to
the beginning situation a stable situation around the implants. Clinical
measurements at control sessions included plaque score, gingival index,
sulcus bleeding and pocket probing depth. Additionally, the occlusion,
retention and stability of the dentures were examined. The implants were
evaluated following the success criteria of Albrektsson. 11 Mesial and distal
marginal bone levels were measured on panoramic radiographies.
Discussion
Patients seeking replacement of their upper denture with an implant-
supported restoration are generally interested in a fixed restoration, but it
is not always possible. Accompanying the loss of supporting alveolar
structure due to resorption, the lip support is lost and can only be
provided by a denture flange. Attempts to provide a fixed restoration can
result in compromises to oral hygiene based on designs with ridge laps.
An alternative has been an overdenture prosthesis, which provides lip
support but has extensions on to the palate, but still gives the patient the
comfort having a free palate. On the other hand, the amount of bone does
not always allow to insert the necessary number of implants for fixed
restorations. Severely resorbed jaws provided with overdentures were
reported as the most demanding cases. 12
The Marius bridge was developed as a fixed bridge alternative
offering lip support that is removable by the patient for hygiene purposes,
with no palatal extension beyond normal crown-alveolar contours. The
reduction or elimination of palatal coverage with maxillary implant-
supported overdentures may be perceived as advantageous to patients
by providing greater comfort through reduction of tissue coverage. 13 The
Marius bridge is a complete-arch, double-structure prosthesis for maxillae
that is removable by the patient for oral hygiene. Satisfactory medium-
term results of survival and patient satisfaction show that the Marius
bridge can be recommended for implant dentistry. The technique may
reduce the need for grafting, because it allows for longer implants to be
placed with improved bone anchorage and prostheses support. 14
An important disadvantage of the Marius Bridge seems to be the
lacking support of the palatal gum tissue. It is shown that the uncovering
of the palate increases the forces transferred to the implants and
especially to the crestal bone. 13
Overdentures supported and retained by endosteal implants depend
upon mechanical components to provide retention. In general, an implant
is loaded via axial and horizontal forces. Besides this, moment loading
can also occur.15 The clinician may be able to make empirical decisions
on attachment selection, depending on the amount of retention desired
and the specific clinical situation,16 but the force transfer to the implants
should always be respected.
Different overdenture attachments are found to effect the stress
distribution in the maxillary bone surrounding the overdenture implants 17
and for different loading locations, significant differences were found
among the different overdenture attachment systems, 18 since every
attachment type has different retention characteristics. 19
Ball attachments are frequently described because of simplicity and
low cost, but retentive capacity of these components may be altered by a
lack of implant parallelism.20 Divergent implants in the maxilla can make
restoration with removable prosthetics difficult when the implants will not
be splinted with a superstructure. Attachments to be used with individual
implants require that the implants be within 10 degrees of divergence. 21
Additionally, primary splinting of fixtures with bar attachments has proved
to be clinically effective for overdentures on osseointegrated implants,
because there is a tendency for better axial load sharing with bars. 22
Studies of maxillary overdentures supported by endosseous
implants often show a high implant failure rate.23 In a study, where all
patients who needed an overdenture and could only be provided with a
minimum number of bilaterally-placed implants, the patients received
either a round 2-mm-diameter bar with clips or ball attachments as a
retentive system. The cumulative implant survival rates after 7 years of
loading were 75.4% in the maxillae and 100% in the mandibles. There
was no difference in implant survival rate between the attachment
systems. Patients with implant losses were characterized by severely
resorbed maxillary ridges and inferior bone quality, together with
unfavorable loading circumstances such as short implants combined with
long leverages. 24 For these reasons we have chosen to use longer
implants in spite of the lack of available bone, inserting them in angulated
position. Additionally, we have chosen a retention system which will not
traumatize the implants during taking away or inserting the denture.
The results of an investigation showed that practically all implant
losses occurred during the first 2 years, whereupon a steady state
seemed to follow for up to 5 years after loading (25). We already know that
the first year is the most critical one for implant failure and also for crestal
bone resorption.26, 27, 28,29, 30, 31 This case showed in spite of
disadvantageous loading conditions and poor bone quality and quantity a
stable situation around the implants.
Although further follow-up and higher case numbers will give more
information about this treatment modality, the actual result is encouraging
and can be recommended for similar cases.
REFERENCES
1. Lekholm U, Zarb GA. Patient selection and preparation. In: Branemark PI,
Zarb GA, Albrektssoon T, editors. Tissue-integrated prostheses:
osseointegration in clinical dentistry. Chicago: Quintessence; 1985. p. 199-
209
2. Desjardins RP. Prosthesis design for osseointegrated implants in the
edentulous maxilla. Int J Oral Maxillofac Implants 1992;7: 311-320
3. Zarb GA, Schmitt A. Implant prosthodontic treatment options for the
edentulous patient. J Oral Rehabil 1995;22:661-671
4. Wicks RA. A systematic approach to definitive planning for osseointegrated
implant prostheses. J Prosthodont 1994;3:237-242
5. Laney WR. Selecting edentulous patients for tissue-integrated prostheses. Int
J Oral Maxillofac Implants 1986;1:129-138
6. Narhi TO, Heyinga M, Voorsmit RA, Kalk W. Maxillary overdentures retained
by splinted and unsplinted implants: a retrospective study. Int JOral
Maxillofac Implants 2001;16:259-266
7. Lewis S, Sharma A, Nishimura R. Treatment of edentulous maxillae with
osseointegrated implants. J Prosthet Dent 1992;68:503-508
8. Aparicio C , Perales P, Rangert B.Tilted implants as an alternative to maxillary
sinus grafting: a clinical, radiologic, and periotest study. Clin Implant Dent
Relat Res. 2001; 3:39-49
9. Hallman M . A prospective study of treatment of severely resorbed maxillae
with narrow nonsubmerged implants: results after 1 year of loading. Int J Oral
Maxillofac Implants. 2001;16 :731-736
10. Widmark G , Andersson B, Andrup B, Carlsson GE, Ivanoff CJ, Lindvall AM.
Rehabilitation of patients with severely resorbed maxillae by means of
implants with or without bone grafts. A 1-year follow-up study. Int J Oral
Maxillofac Implants. 1998;13:474-482
11. Albrektsson T, Sennerby L. State of the art in oral implants. J Clin
Periodontol. 1991;18:474-481
12. Jemt T , Lekholm U. Implant treatment in edentulous maxillae: a 5-year follow-
up report on patients with different degrees of jaw resorption. Int J Oral
Maxillofac Implants. 1995;10:303-311
13. Ochiai KT, Williams BH, Hojo S, Nishimura R & Caputo AA. Photoelastic
analysis of the effect of palatal support on various implant-supported
overdenture designs. J Prosthet Dent 2004;91:421-427
14. Fortin Y , Sullivan RM, Rangert BR. The Marius implant bridge: surgical and
prosthetic rehabilitation for the completely edentulous upper jaw with
moderate to severe resorption: a 5-year retrospective clinical study.Clin
Implant Dent Relat Res. 2002;4:69-77
15. Heckmann SM, Winter W, Meyer M, Weber HP, Wichmann MG. Overdenture
attachment selection and the loading of implant and denture-bearing area.
Part 2: A methodical study using five types of attachment. Clin Oral Implants
Res. 2001;12:640-647
16. Petropoulos VC, Smith W. Maximum dislodging forces of implant overdenture
stud attachments. Int J Oral Maxillofac Implants. 2002;17:526-535.
17. Chun HJ, Park DN, Han CH, Heo SJ, Heo MS, Koak JY. Stress distributions
in maxillary bone surrounding overdenture implants with different overdenture
attachments. J Oral Rehabil. 2005; 32:193-205
18. Porter JA Jr, Petropoulos VC, Brunski JB. Comparison of load distribution for
implant overdenture attachments. Int J Oral Maxillofac Implants.
2002;17:651-662
19. Chung KH, Chung CY, Cagna DR, Cronin RJ Jr. Retention characteristics of
attachment systems for implant overdentures. J Prosthodont. 2004;13:221-
226
20. Gulizio MP, Agar JR, Kelly JR, Taylor TD. Effect of implant angulation upon
retention of overdenture attachments. J Prosthodont. 2005;14:3-11
21. Schneider AL, Kurtzman GM. Restoration of divergent free-standing implants
in the maxilla. J Oral Implantol. 2002;28:113-116
22. Duyck J, Van Oosterwyck H, Vander Sloten J, De Cooman M, Puers R &
Naert I. In vivo forces on oral implants supporting a mandibular overdenture:
the influence of attachment system. Clin Oral Invest 1999; 3:201–207
23. Mericske-Stern R , Oetterli M, Kiener P, Mericske E. A follow-up study of
maxillary implants supporting an overdenture: clinical and radiographic
results. Int J Oral Maxillofac Implants. 2002;17:678-686
24. Bergendal T, Engquist B. Implant-supported overdentures: a longitudinal
prospective study. Int J Oral Maxillofac Implants. 1998;13:253-262
25. Widmark G , Andersson B, Carlsson GE, Lindvall AM, Ivanoff CJ.
Rehabilitation of patients with severely resorbed maxillae by means of
implants with or without bone grafts: a 3- to 5-year follow-up clinical report. Int
J Oral Maxillofac Implants. 2001;16:73-79
26. Allen PF, McMillan AS, Smith DG. Complications and maintenance
requirements of implant-supported prostheses provided in a UK dental
hospital. Br Dent J 1997;182: 298–302
27. Adell R, Lekholm U, Rockler B, et al. A 15-year study of osseointegrated
implants in the treatment of the edentulous jaw. Int J Oral Surg 1981; 10:
387-416
28. Bidez MW, Misch CE. Issues in bone mechanics related to oral implants.
Implant Dent 1992;1: 289-294
29. Chaytor DV, Zarb GA, Schmitt A, Lewis DW. The longitudinal effectiveness of
osseointegrated dental implants. The Toronto study: Bone level changes. Int
J Periodontics Restorative Dent 1991; 11: 113-126
30. Cox JF, Zarb GA. The longitudinal clinical efficacy of osseointegrated
implants: A 3-year report. Int J Oral Maxillofac Implants 1987; 2: 91-100
31. Weber HP, Buser D, Fiorellini JP, Williams RC. Radiographic evaluation of
crestal bone levels adjacent to nonsubmerged titanium implants. Clin Oral
Implants Res 1992; 3: 181-188
Legend of Figures:
Figure 1: The implants introrally with healing abutments
Figure 2: Radiographic view of mouth after implant insertion
Figure 3: Try-in of the individual bar
Figure 4: The metal framework and bar
Figure 5: The finished denture
Figure 6: The denture in place
Figure 7: Radiographic view after 6th months
Figure 8: Radiographic view after 12th months
Fig 1
Fig 2
Fig 3
Fig 4
Fig 5
Fig 6
Fig 7
Fig 8