Dental Implants in Cleft Lip, Alveolus, and Palate Patients: A Systematic Review Kai Wermker, MD, DMD1/Susanne Jung, MD, DMD2/ Ulrich Joos, MD, DMD, PhD2/Johannes Kleinheinz, MD, DMD, PhD2 Purpose: Missing teeth are a major problem in cleft patients, who require specialized prosthetic management, including dental implants. The aim of this review was to investigate the optimal date for implant insertion in patients born with cleft lip and palate after bone grafting and to assess the long-term prognosis of the inserted dental implants. Materials and Methods: A systematic review of the current literature electronically in several databases and additional hand searching were performed. Relevant publications were assessed with regard to their evidence according to the guidelines of the Oxford Centre for Evidence-Based Medicine. Results: Forty-nine publications (prospective and retrospective clinical studies, case series, and case reports) were included for analysis, but only 18 clinical papers reported survival rates for dental implants (in all, 670 implants in 460 cleft patients). Most studies were evidence level 3b (case-control studies) or 4 (case series, case reports). Reported 5-year survival rates for dental implants in cleft patients ranged from 80% to 96% (mean, 88.6%). Implant placement is favored after growth is complete and is generally recommended within 4 to 6 months after bone grafting. Conclusions: Dental implants in patients with cleft lip and palate show high success rates and allow for sufficient oral rehabilitation. However, because of a lack of sufficient prospective clinical studies on dental implants in cleft patients, the available evidence is poor and insufficient. Int J Oral Maxillofac Implants 2014;29:384–390. doi: 10.11607/jomi.3303 Key words: bone grafting, cleft lip and palate, dental implants, implant survival, osteoplasty, review
C
left lip, alveolus, and palate account for the most common human malformations, with an incidence of 1:700 to 1:500. Their treatment includes oral and maxillofacial surgery, otorhinolaryngology, orthodontics, and speech therapy.1 The basis of a functional restoration of the masticatory system is the surgical closure of the cleft lip and palate. A common aim is the early reconstruction of a normal anatomy to allow for physiologic growth of the midface structures and to enable children to develop undisturbed mastication, speech, hearing, and esthetics and therefore psychologic and social qualities. These goals should be achieved in the first year.2–4
1Department
of Oral and Cranio-Maxillofacial Surgery, Fachklinik Hornheide at the Westfalian Wilhelms-University Muenster, Muenster, Germany. 2Department of Oral and Cranio-Maxillofacial Surgery, University Hospital Muenster, Muenster, Germany. Correspondence to: Kai Wermker, Department of Oral and Cranio-Maxillofacial Surgery, Fachklinik Hornheide, Dorbaumstr. 300, 48157 Muenster, Germany. Fax: +49-251-3287-424. Email: [email protected] ©2014 by Quintessence Publishing Co Inc.
Reconstruction of the alveolar ridge can be achieved by the use of a gingivoperiosteoplasty in combination with closure of the lip.2,5 However, despite the bony regeneration, 60% to 80% of these patients require a second bone graft (typically done by inserting spongiosa from the ilium to bridge the residual alveolar gap) to fully restore the alveolar ridge and to allow for dental implant placement.1,6 The common means of reconstruction of the anterior alveolar defect is secondary bone grafting at the age of 8 to 11 years, while the mixed dentition is present. Two-thirds development of the maxillary canine generally defines the optimal date for bone grafting to enable the tooth to erupt in the transplanted bone.7–10 A less successful strategy is primary bone grafting, which closes the bony defect in the primary dentition. Its disadvantages are the often-observed resorption of the transplanted bone and pronounced inhibition of maxillary growth in the sagittal and transverse directions with consecutive midface hypoplasia. Tertiary bone grafting is performed in fully grown patients starting at the age of 17. Dental treatment of the gap depends on the condition of the remaining teeth in the area of the cleft; aplasia or dysplasia of these teeth is common in cleft patients. The reported incidence of missing teeth in
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the permanent dentition in the cleft population is between 30% and 50% and is therefore sixfold higher than in noncleft subjects.1,11,12 It is possible to restore missing teeth in cleft patients with orthodontic gap closure, conventional prosthetics (fixed, removable, or overlay), or dental implants. Orthodontic gap closure may be a good option for bilateral missing or hypoplastic teeth but is problematic for unilateral missing teeth with consecutive dental asymmetry. The biggest drawback of conventional prosthetics such as fixed partial dentures is, in addition to the loss of healthy tooth substance, the absence of physiologic strain on the osteoplastically augmented alveolar ridge.1 An increasingly favored method nowadays is the insertion of endosseous dental implants to replace missing teeth, especially the maxillary lateral incisors in cleft patients. In most cases, single implants with corresponding crowns are used to restore the dental arch; reported survival rates are above 95% after 7 years for osseointegrated implants.13,14 In addition to the quality of the long-term functional and esthetic rehabilitation, the osseoprotective function of endosseous implants in an augmented alveolar area argues especially in favor of this therapy.1,6 Several confounding factors have to be considered in the treatment of cleft patients. The anterior arches come with high expectations concerning the esthetic outcome. The region of interest has generally been surgically treated at least twice before an implant can be inserted. Primary closure and bone grafting have left the tissue scarred; therefore, wound closure and regeneration in the sense of an optimal esthetic soft tissue design can be impaired. The implant is generally inserted in augmented bone. Depending on the duration of the wound-healing phase, parts of the bone may resorb again.10,15–19 The physiologic stress/load transmitted by the implant can help to prevent further bone loss and atrophy.20–22 With the exception of one study,18 for most researchers, implant placement in a growing skeletal system is not an option23–26; therefore, a lengthy waiting period occurs between bone grafting and implant insertion. To allow for successful implantation and to avoid delayed osseointegration and implant loss, additional bony augmentation may be performed during implant placement.6 To date, there is a lack of evidence concerning treatment options, management, and success rates of dental implants in cleft patients. To the best of the authors’ knowledge, comprehensive reviews are still missing, and therapy may differ significantly between cleft centers. Thus, the present review sought to investigate the optimal date of implant insertion in patients suffering from cleft palate after bone grafting and, in particular, to analyze the long-term prognosis of the inserted dental implants. Answers to these questions are im-
portant and useful for all clinicians dealing with cleft patients, so that they may base their treatment options on a broader base of evidence to achieve predictable and good results for as many cleft patients as possible.
Materials and Methods A literature search was conducted using the electronic databases the Cochrane Library, MEDLINE, EMBASE, BIOSIS, SciSearch, AMED, DAHTA, DIMDI, and Q-SENSEI for relevant articles published in English between January 1990 and December 2012. The search was limited to this time frame because in recent decades, important changes and advances have occurred in the treatment of cleft patients and in implant dentistry. Medical Subject Headings (MeSH terms) and key words were used relating to dental implants, implantology/implant dentistry, osteoplasty, bone grafting, and cleft lip, alveolus, and palate. Additionally, a hand search was performed in the relevant common journals and in additional relevant articles. Papers dealing with bone grafting and/or dental implants and cleft lip and palate were included for further analysis. Papers presenting data from a noncleft sample, experimental and in vitro papers, animal studies, and technical notes were excluded from further analysis. The significance and evidence of the corresponding articles were evaluated by two authors (KW, SJ) following the guidelines of the Oxford Centre for Evidence-Based Medicine (EbM) (Table 1).27 For studies presenting implant survival rates, a three-point scale to assess quality (low, moderate, high) and the risk of bias (low, moderate, high) was performed by two authors (KW, SJ), and interrater reliability was calculated using Cohen’s kappa. In cases of different ratings, a third rater (JK) evaluated the study. For analysis of implant survival, descriptive data were extracted from the identified studies with regard to the level of evidence and reported follow-up time frames. The number of implants placed in all relevant studies and the number of successfully incorporated implants in function at the end of the observation period (survived implants) were calculated. Success rates were determined by dividing the number of surviving implants by the total number of implants placed. Because of the heterogeneity of the studies, a metaanalysis or analytic statistics could not be performed.
Results Of 90 published clinical studies and case reports, 49 articles met the authors’ requirements and were included for further analysis. Table 2 summarizes these 49 The International Journal of Oral & Maxillofacial Implants 385
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Table 1 Levels of Evidence According to the Oxford Centre for Evidence-Based Medicine27
Table 2 Evidence Level of Studies Included in This Review
Level of evidence
EbM level27
Characteristics
1a 1b
Systematic review of randomized controlled trials Randomized controlled trial
2a 2b 2c
Systematic review of cohort studies Prospective cohort study “Outcomes” research
3a 3b
Systematic review of case-control studies Case-control study
4
Case series/case reports
5
Expert opinion
No. of studies [references] Retrospective
Prospective
Total
1b
0
0
0
1c
0
0
0
2b
0
16
1
2c
128
0
1
3b
1220–22,29–37
938–46
4
2612,17,18,47,54–75
0
26
Total
39
10
49
21
Reprinted with permission from University of Oxford, Centre for EvidenceBased Medicine.
publications in context with their evidence level and with regard to their design (prospective or retrospective). Only 18 articles presented survival rates of dental implants in cleft patients. The other 31 articles were case series or case reports with low levels of evidence.
Survival Rates of Dental Implants in Cleft Lip and Palate Patients
Table 3 summarizes the clinical studies that investigated the survival rates of dental implants in patients with clefts. This list of identified studies dealing with implant survival in cleft patients is ordered according to the evidence level and, within each evidence level, according to reported follow-up or observation time, beginning with the shortest. Interrater reliability was good for quality assessment (Cohen’s kappa = 0.700) and risk of bias assessment (Cohen’s kappa = 0.833). In these 18 studies, 670 implants in 460 cleft patients were analyzed for implant survival. The accumulated descriptive data in different time frames (without considering different levels of evidence of the studies) produced a 2-year survival rate of 89.2% (74 implants in 61 patients; two studies); a 3-year survival rate of 94.1% (265 implants in 183 patients; seven studies); and a 5-year survival rate of 88.6% (268 implants in 166 patients; six studies). With regard to the EbM level, the majority of the publications were characterized as evidence level 3b, ie, case-control studies. This reflects the absence of control groups and the retrospective design of the studies. One research group prospectively analyzed implant survival after maxillary bone grafting, comparing cleft patients to a group of patients after maxillary trauma and consecutive loss of anterior alveolar crest, with a follow-up period of 48 months.6 The survival rates, analyzed by Kaplan-Meier, did not show statistically significant differences: The 1- and 5-year survival rates
were 84% (80% in cleft patients; n= 20) and 89% (88% in the trauma group; n = 20), respectively. Secondary parameters, such as bone loss, gingival recession, or peri-implant probing depths, also showed no significant differences. To sum up the data, the survival rates of dental implants according to the listed data ranged from 86.7% to 96.7% over 3 years. The 5-year survival rates hovered between 80% and 98.6%. The study with the longest observation period (16 years) reported a 71% rate of functional successful dental implants as single-tooth replacements in cleft patients.29 This study was included in the analysis because of the exceptionally long follow-up time, although, because of the study design, assessment of the EbM level was not possible.
Optimal Date for Implant Insertion in Cleft Patients
Concerning the ideal age for implant insertion, there seems to be a consensus that, in cleft patients, dental implants should be placed after growth is complete. In only 1 of the 49 included publications (Table 2) implant placement in the growing skull in a 10-year-old cleft patient was reported.18 All other authors favored implant insertion after adolescence, when growth was finished. The time interval between secondary bone grafting (at the age of 8 to 11 years) and implant placement was not systematically reported in the analyzed studies. In one prospective study, the mean interval in nine patients was 57 months.30 Other studies did not report time intervals sufficiently to enable calculation of summary data. Fourteen publications analyzed the time between tertiary bone grafting and implant insertion. Most authors (eight studies) found that a time interval of 4 to 6 months was most suitable to avoid major bone resorption (and a consequent need for regrafting) and
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Table 3 Patient, Implant, and Outcome Data and Quality of Evidence from Clinical Studies Presenting Survival Rates of Endosseous Dental Implants in Patients with Clefts Year of publication
Reference
EbM level27
No. of patients
No. of implants
Survival rate (%)
Follow-up time (y)
Quality
Risk of bias
Landes6
2006
2b
20
25
80.0
5
H
L
Duskova et al41
2007
3b
45
45
86.7
2
M
M
Lilja et al45
1998
3b
16
29
93.0
2
M
M
al30
2012
3b
17
24
95.8
3
M
M
De Barros Ferreira32
2010
3b
120
123
94.3
3
H
M
Härtel et al22
1999
3b
11
17
96.0
3
M
M
Jansma et al31
1999
3b
10
31
96.7
3
M
M
Kearns et al38
1997
3b
14
29
90.0
3
M
M M
Landes et
al34
1994
3b
6
23
91.0
3
M
Jensen et al33
1998
3b
16
20
90.0
4
M
M
Lalo et al44
2007
3b
12
12
91.7
5
M
M
Matsui et al40
2007
3b
47
71
98.6
5
M
M
Kramer et al43
2005
3b
45
75
82.2
5
M
M
Deppe et al21
2004
3b
32
35
91.4
5
M
M
Laine et al37
2002
3b
10
50
85.7
5
M
M
Takahashi et al39
2008
3b
16
21
90.9
6
M
M
Arcuri etl
al64
2010
4
5
18
94.4
3
L
H
Krieger et al29
2009
-*
18
22
71.0
16
M
H
Sándor et
Study quality, risk of bias assessment: L = low, M = moderate, H = high. *Assessment of EbM level not applicable because of study design (analysis of insurance data).
to place implants in the alveolar cleft area with the lowest complication rates.19,20,31,32,38–40,70 Two studies presented unfavorable results of up to 43% disturbed wound healing and up to 86% partial bone loss for simultaneous tertiary bone grafting and implant insertion.33,47 Two studies also analyzed and proposed shorter time intervals of 1.5 to 2 months and 3 months, respectively.22,71 In two studies, longer periods of 6 to 12 and 6 to 13 months between tertiary bone grafting and implantation were analyzed; neither was associated with a greater need for regrafting.6,17
Discussion When the relevant literature dealing with implant placement in cleft patients is evaluated, the low level of evidence becomes obvious. There is currently only one study that prospectively investigated the survival rates and the relevant prognostic factors of dental implants in patients with clefts after bone grafting on the one hand and patients after maxillary trauma and bony augmentation on the other hand, reaching an EbM level of 2b.6 The others are case-control studies, which retrospectively investigated different patient populations, matching evidence levels 3b or 4 (case series and case reports). To date, the data must be re-
garded as insufficient, with a lack of prospective clinical trials with a representative number of subjects and defined control groups. Regarding the study of cleft patients, the requirements of evidence-based medicine are hard to meet. One reason is the incidence of cleft alveolus and palate; with a rate of 1:500 to 1:700, cleft patients are not incredibly common. Furthermore, in the analysis of the growing skull, observation periods of several years are sought to achieve significant results comparing therapies, risks, and outcomes. A clean randomized trial seems scarcely viable simply because of ethical considerations, so a level 1 study will not be realizable. Another challenge in designing a study dealing with patients with cleft lip, alveolus, and palate is the implementation of an apt control group. General possibilities and limitations in the analysis and evaluation of therapeutic concepts in patients with cleft lip and palate were extensively discussed previously.72 Secondary bone grafting of the residual alveolar cleft during the mixed dentition years is currently the favored method to allow for physiologic and esthetic rehabilitation.1,7–10 Placement of endosseous dental implants in the growing jaw is generally not recommended,23–26 with the exception of one study, which reported good results when implants were placed before the growth spurt.18 The International Journal of Oral & Maxillofacial Implants 387
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The clinical challenge resides in the management of the time lag between bone grafting and implant placement. Wound and bone healing and remodeling are pitted against atrophy and loss of bone height. To prevent excessive atrophy, a physiologic functional strain on the bone is mandatory.73 With this in mind, the optimal timing for implant placement would be 3 to 6 months after bone grafting, as recommended by most authors, with a range from 2 to 12 months.17,22,70,71 This broad range is another result of the lack of evidence/ data. Short-term implant insertion at a 6-month interval can be easily performed after tertiary bone grafting without interfering with the growth of the jaw, but this cannot be done after secondary bone grafting. Therefore, in most cases after secondary bone grafting, an additional surgery for augmentative bone grafting (regrafting) is necessary before implant placement. Subsequently, early implant insertion and loading is recommended.6 Systematic reviews have reported a 97% survival rate at 7 years for implants used for single-tooth replacement in native bone.13,14 The reported 5-year survival rates of implants in the area of an alveolar cleft after bone grafting range from 80% to 96%, with a mean of 88.6%.6,17,18,32,39,74 A prospective study found a 5-year survival rate of 80% in a group of cleft patients, compared to 88% survival in the control group of posttraumatic augmentation and implantation patients, by Kaplan-Meier analysis; the difference was not significant.6 To the authors’ knowledge, this is the first systematic review to analyze the survival rates of dental implants in cleft patients. Concerning the optimal date of implant placement, only one other review also analyzed this question and reached similar conclusions.75 It has to be kept in mind that this review, with the exception of one prospective study, summarized retrospective data exclusively. A retrospective study design means that the risk of selection bias (eg, concerning patient selection, consistency of compared groups and therapies) is higher and the quality of the data is lower in comparison to a prospectively designed study. Another weakness of this systematic review is the fact that, because of the heterogenous designs of the studies and different quality of reported data in the analyzed studies, it was not possible to generate a high-quality summary of the data. It was possible to sum up the data only in a descriptive manner; statistics such as forest plots, summarized Kaplan-Meier survival analysis, or even a meta-analysis were not feasible. For the successful dental rehabilitation of patients with cleft lip, alveolus, and palate, secondary bone grafting of the jaw with an autologous bone graft from the hip at the age of 8 to 11 years during the mixed dentition, combined with implant placement after
growth is complete, is the most efficient and favored method. Nevertheless, in most of these cases, further bony augmentation before inserting dental implants 4 to 6 months later is necessary. With 5-year survival rates up to and above 90%, the insertion of endosseous implants represents a reliable procedure for oral rehabilitation in cleft patients, with a good long-term prognosis. According to current clinical studies and data of this review, a 5-year survival rate above 88% can be expected. The therapeutic alternative is the orthodontic closure of the dental gap. Therefore, augmentative therapy is not necessary, but its striking disadvantage is the loss of the physiologic architecture of the dental arch, especially the positions of the canines, the asymmetric results in unilateral clefts, and the imminent root resorption after large orthodontic movements. The insertion of endosseous dental implants represents the most functional and esthetic means to restore the bony alveolar defect as well as the dental arch in patients with cleft lip and palate. Nevertheless, concerning dental replacement of missing teeth in cleft patients, the absence of evidence concerning some open questions is obvious. In general, to date, there is not enough evidence to determine whether replacing missing teeth with dental implants is more favorable than orthodontic gap closure regarding different parameters (eg, unilateral or bilateral missing teeth, number of missing teeth, type and extent of clefting, influence of different treatment concepts). Concerning insertion of dental implants in the area of the alveolar cleft, the influence of implant length and diameter has not been investigated sufficiently. Most retrospective studies presented survival rates of implants in a descriptive manner. Prospective clinical trials are needed to allow for adequate analysis of implant survival rates (eg, analysis according to Kaplan-Meier) and to subsequently enable pooling and adequate summing up of data. This would facilitate systematic reviews with higher statistical quality or a meta-analysis. Critically, it must be kept in mind that generating studies with high levels of evidence in cleft patients is more difficult than in other fields, as discussed previously.72
Conclusion Reported 5-year survival rates for dental implants in clefts range from 80% to 96% (mean, 88.6%). Implant placement is favored after completion of growth and is recommended in most cases within 4 to 6 months after bone grafting. The results suggest that dental implants allow for a sufficient functional and esthetic oral rehabilitation in patients with cleft lip and palate,
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although implant survival rates are lower in cleft patients than in noncleft subjects. This systematic review clearly highlights the lack of evidence concerning the placement of dental implants in cleft patients. More research, especially prospective clinical trials, is needed to broaden the database and clarify the remaining open questions.
Acknowledgments The authors declare that they have no competing interests. Author contributions: KW designed the study; KW, SJ, and JK drafted the manuscript; KW searched the relevant literature, and KW and SJ read the searched literature; KW and SJ performed data analysis; UJ gave important intellectual content to the study design; JK gave important content to the study design, revised the manuscript, and gave final approval to the version being published; all authors read and approved the final manuscript.
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37. Laine J, Vähätalo K, Peltola J, Tammisalo T, Happonen RP. Rehabilitation of patients with congenital unrepaired cleft palate defects using free iliac crest bone grafts and dental implants. Int J Oral Maxillofac Implants 2002;17(4):573–580. 38. Kearns G, Perrott DH, Sharma A, Kaban LB, Vargervik K. Placement of endosseous implants in grafted alveolar clefts. Cleft Palate Craniofac J 1997;34(6):520–525. 39. Takahashi T, Inai T, Kochi S, et al. Long-term follow-up of dental implants placed in a grafted alveolar cleft: Evaluation of alveolar bone height. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;105(3):297–302. 40. Matsui Y, Ohno K, Nishimura A, Shirota T, Kim S, Miyashita H. Longterm study of dental implants placed into alveolar cleft sites. Cleft Palate Craniofac J 2007;44(4):444–447. 41. Duskova M, Kotova M, Sedlackova K, Leamerova E, Horak J. Bone reconstruction of the maxillary alveolus for subsequent insertion of a dental implant in patients with cleft lip and palate. J Craniofac Surg 2007;18(3):630–638. 42. Dusková M, Kotóvá M, Urban F, et al. Reconstruction of maxilla alveolus for application of dental implant in patients with cleft defect. Acta Chir Plast 2004;46(4):115–121. 43. Kramer FJ, Baethge C, Swennen G, Bremer B, Schwestka-Polly R, Dempf R. Dental implants in patients with orofacial clefts: A longterm follow-up study. Int J Oral Maxillofac Surg 2005;34(7):715–721. 44. Lalo J, Kayali A, Toudjine B, Majourau-Bouriez A, Essaddam H, Pavy B. [Prosthetic rehabilitation with dental implant in cleft lip and palate: A ten-year retrospective study]. Rev Stomatol Chir Maxillofac 2007;108(5):398–405. 45. Lilja J, Yontchev E, Friede H, Elander A. Use of titanium dental implants as an integrated part of a CLP protocol. Scand J Plast Reconstr Surg Hand Surg 1998;32(2):213–219. 46. Nagasao T, Miyamoto J, Jin H, et al. The dynamics in implantation for patients with clefts. Cleft Palate Craniofac J 2006;43(1):84–91. 47. Fukuda M, Takahashi T, Yamaguchi T, Kochi S. Placement of endosteal implants combined with chin bone onlay graft for dental reconstruction in patients with grafted alveolar clefts. Int J Oral Maxillofac Surg 1998;27(6):440–444. 48. Bartee BK, Perkins CE. Reconstruction of an atrophic edentulous maxilla with unilateral cleft lip and palate (UCLP) using sub-antral augmentation and osseointegrated implants: Case report and 3-year follow-up. Tex Dent J 1995;112(11):35–41. 49. Buis J, Rousseau P, Soupre V, Martinez H, Diner PA, Vazquez MP. “Distraction” of grafted alveolar bone in cleft case using endosseous implant. Cleft Palate Craniofac J 2001;38(4):405–409. 50. De Rezende MLR, Amado FM. Osseointegrated implants in the oral rehabilitation of a patient with cleft lip and palate and ectodermal dysplasia: A case report. Int J Oral Maxillofac Implants 2004;19(6):896–900. 51. Dostálová T, Holakovsk´y J, Bartonová M, Seydlová M, Smahel Z. Denture reconstruction of the edentulous upper jaw in cleft palate using implants—Clinical report. Acta Chir Plast 2007;49(4):89–93. 52. Flanagan D. An implant-retained maxillary overdenture to obturate a patent oronasal communication: A case report. J Oral Implantol 2009;35(1):12–17. 53. Hakan Tuna S, Pekkan G, Buyukgural B. Rehabilitation of an edentulous cleft lip and palate patient with a soft palate defect using a bar-retained, implant-supported speech-aid prosthesis: A clinical report. Cleft Palate Craniofac J 2009;46(1):97–102. 54. Harrison JW. Dental implants to rehabilitate a patient with an unrepaired complete cleft of the hard and soft palate: A clinical report. Cleft Palate Craniofac J 1992;29(5):485–488. 55. Iida S. [Implant therapy for bone loss in the premaxillar part of the bilateral cleft lip and palate patient]. Nihon Hotetsu Shika Gakkai Zasshi 2008;52(2):232–235. 56. Isono H, Kaida K, Hamada Y, et al. The reconstruction of bilateral clefts using endosseous implants after bone grafting. Am J Orthod Dentofacial Orthop 2002;121(4):403–410.
57. Le BT, Woo I. Alveolar cleft repair in adults using guided bone regeneration with mineralized allograft for dental implant site development: A report of 2 cases. J Oral Maxillofac Surg 2009;67(8):1716–1722. 58. Lefkove MD, Matheny B, Silverstein L. Implant prosthodontic procedures for a completely edentulous patient with cleft palate. J Oral Implantol 1994;20(1):82–87. 59. Lund TW, Wade M. Use of osseointegrated implants to support a maxillary denture for a patient with repaired cleft lip and palate. Cleft Palate Craniofac J 1993;30(4):418–420. 60. Nakai H, Niimi A, Fujimoto T, Ueda M. Prosthetic treatment using an osseointegrated implant after secondary bone grafting of a residual alveolar cleft: A case report. Int J Oral Maxillofac Implants 1998;13(3):412–415. 61. Pektas ZO, Kircelli BH, Bayram B, Kircelli C, Uckan S. Alveolar cleft closure by distraction osteogenesis with skeletal anchorage during consolidation. Int J Oral Maxillofac Implants 2008;23(1):147–152. 62. Rubo de Rezende ML, de Melo LGN, Hamata MM, Monteiro-Amado F. Particulate inlay nasal graft with immediate dental implant placement in a patient with repaired alveolar cleft: Case report. Implant Dent 2008;17(3):332–338. 63. Sabri R. Cleft lip and palate management with maxillary expansion and space opening for a single tooth implant. Am J Orthod Dentofacial Orthop 2000;117(2):148–155. 64. Sándor GKB, Carmichael RP, Brkovic BMB. Dental implants placed into alveolar clefts reconstructed with tongue flaps and bone grafts. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109(2):e1–7. 65. Sawaki M, Ueno T, Kagawa T, et al. Dental implant treatment for a patient with bilateral cleft lip and palate. Acta Med Okayama 2008;62(1):59–62. 66. Sedlackova K, Duskova M, Strnadel T, Kotova M, Haas M. Using dental implants in the prosthetic rehabilitation of patients with cleft defect type II. Cleft Palate Craniofac J 2011;48(1):98–102. 67. Shifman A, Finkelstein Y. Rhinorrhea induced by loading of dental implants supporting an obturator prosthesis: A clinical report. J Prosthet Dent 2003;89(5):450–452. 68. Vecchiatini R, Mobilio N, Raimondi F, Catapano S, Calura G. Implantprosthetic rehabilitation for a patient with monolateral cleft lip and palate: A clinical report. Quintessence Int 2009;40(6):445–447. 69. Verdi FJ Jr, SLanzi GL, Cohen SR, Powell R. Use of the Brånemark implant in the cleft palate patient. Cleft Palate Craniofac J 1991;28(3):301–303. 70. Chiapasco MT. Discussion on Takahashi et al, Use of endosseous dental implants for dental reconstruction of patients with grafted alveolar clefts. J Oral Maxillofac Surg 1997;55(6):584. 71. Schwenzer N, Ehrenfeld M. [Bone repair and secondary implant management of the maxillary cleft]. Fortschr Kiefer Gesichtschir 1993;38:110–112. 72. Piffko J, Meyer U, Joos U. [Possibilities and limitations in evaluating treatment concepts in lip-jaw-palate clefts]. Mund Kiefer Gesichtschir 2002;6(1):49–52. 73. Iino M, Ishii H, Sato J, Seto K. Histological evaluation of autogenous iliac particulate cancellous bone and marrow grafted to alveolar clefts—A preliminary report of five young adult cases. Cleft Palate Craniofac J 2000;37(1):55–60. 74. Carmichael RP, Sándor GKB. Use of dental implants in the management of cleft lip and palate. Atlas Oral Maxillofac Surg Clin North Am 2008;16(1):61–82. 75. Pena WA, Vargervik K, Sharma A, Oberoi S. The role of endosseous implants in the management of alveolar clefts. Pediatr Dent 2009;31(4):329–333.
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C
left lip, alveolus, and palate account for the most common human malformations, with an incidence of 1:700 to 1:500. Their treatment includes oral and maxillofacial surgery, otorhinolaryngology, orthodontics, and speech therapy.1 The basis of a functional restoration of the masticatory system is the surgical closure of the cleft lip and palate. A common aim is the early reconstruction of a normal anatomy to allow for physiologic growth of the midface structures and to enable children to develop undisturbed mastication, speech, hearing, and esthetics and therefore psychologic and social qualities. These goals should be achieved in the first year.2–4
1Department
of Oral and Cranio-Maxillofacial Surgery, Fachklinik Hornheide at the Westfalian Wilhelms-University Muenster, Muenster, Germany. 2Department of Oral and Cranio-Maxillofacial Surgery, University Hospital Muenster, Muenster, Germany. Correspondence to: Kai Wermker, Department of Oral and Cranio-Maxillofacial Surgery, Fachklinik Hornheide, Dorbaumstr. 300, 48157 Muenster, Germany. Fax: +49-251-3287-424. Email: [email protected] ©2014 by Quintessence Publishing Co Inc.
Reconstruction of the alveolar ridge can be achieved by the use of a gingivoperiosteoplasty in combination with closure of the lip.2,5 However, despite the bony regeneration, 60% to 80% of these patients require a second bone graft (typically done by inserting spongiosa from the ilium to bridge the residual alveolar gap) to fully restore the alveolar ridge and to allow for dental implant placement.1,6 The common means of reconstruction of the anterior alveolar defect is secondary bone grafting at the age of 8 to 11 years, while the mixed dentition is present. Two-thirds development of the maxillary canine generally defines the optimal date for bone grafting to enable the tooth to erupt in the transplanted bone.7–10 A less successful strategy is primary bone grafting, which closes the bony defect in the primary dentition. Its disadvantages are the often-observed resorption of the transplanted bone and pronounced inhibition of maxillary growth in the sagittal and transverse directions with consecutive midface hypoplasia. Tertiary bone grafting is performed in fully grown patients starting at the age of 17. Dental treatment of the gap depends on the condition of the remaining teeth in the area of the cleft; aplasia or dysplasia of these teeth is common in cleft patients. The reported incidence of missing teeth in
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Wermker et al
the permanent dentition in the cleft population is between 30% and 50% and is therefore sixfold higher than in noncleft subjects.1,11,12 It is possible to restore missing teeth in cleft patients with orthodontic gap closure, conventional prosthetics (fixed, removable, or overlay), or dental implants. Orthodontic gap closure may be a good option for bilateral missing or hypoplastic teeth but is problematic for unilateral missing teeth with consecutive dental asymmetry. The biggest drawback of conventional prosthetics such as fixed partial dentures is, in addition to the loss of healthy tooth substance, the absence of physiologic strain on the osteoplastically augmented alveolar ridge.1 An increasingly favored method nowadays is the insertion of endosseous dental implants to replace missing teeth, especially the maxillary lateral incisors in cleft patients. In most cases, single implants with corresponding crowns are used to restore the dental arch; reported survival rates are above 95% after 7 years for osseointegrated implants.13,14 In addition to the quality of the long-term functional and esthetic rehabilitation, the osseoprotective function of endosseous implants in an augmented alveolar area argues especially in favor of this therapy.1,6 Several confounding factors have to be considered in the treatment of cleft patients. The anterior arches come with high expectations concerning the esthetic outcome. The region of interest has generally been surgically treated at least twice before an implant can be inserted. Primary closure and bone grafting have left the tissue scarred; therefore, wound closure and regeneration in the sense of an optimal esthetic soft tissue design can be impaired. The implant is generally inserted in augmented bone. Depending on the duration of the wound-healing phase, parts of the bone may resorb again.10,15–19 The physiologic stress/load transmitted by the implant can help to prevent further bone loss and atrophy.20–22 With the exception of one study,18 for most researchers, implant placement in a growing skeletal system is not an option23–26; therefore, a lengthy waiting period occurs between bone grafting and implant insertion. To allow for successful implantation and to avoid delayed osseointegration and implant loss, additional bony augmentation may be performed during implant placement.6 To date, there is a lack of evidence concerning treatment options, management, and success rates of dental implants in cleft patients. To the best of the authors’ knowledge, comprehensive reviews are still missing, and therapy may differ significantly between cleft centers. Thus, the present review sought to investigate the optimal date of implant insertion in patients suffering from cleft palate after bone grafting and, in particular, to analyze the long-term prognosis of the inserted dental implants. Answers to these questions are im-
portant and useful for all clinicians dealing with cleft patients, so that they may base their treatment options on a broader base of evidence to achieve predictable and good results for as many cleft patients as possible.
Materials and Methods A literature search was conducted using the electronic databases the Cochrane Library, MEDLINE, EMBASE, BIOSIS, SciSearch, AMED, DAHTA, DIMDI, and Q-SENSEI for relevant articles published in English between January 1990 and December 2012. The search was limited to this time frame because in recent decades, important changes and advances have occurred in the treatment of cleft patients and in implant dentistry. Medical Subject Headings (MeSH terms) and key words were used relating to dental implants, implantology/implant dentistry, osteoplasty, bone grafting, and cleft lip, alveolus, and palate. Additionally, a hand search was performed in the relevant common journals and in additional relevant articles. Papers dealing with bone grafting and/or dental implants and cleft lip and palate were included for further analysis. Papers presenting data from a noncleft sample, experimental and in vitro papers, animal studies, and technical notes were excluded from further analysis. The significance and evidence of the corresponding articles were evaluated by two authors (KW, SJ) following the guidelines of the Oxford Centre for Evidence-Based Medicine (EbM) (Table 1).27 For studies presenting implant survival rates, a three-point scale to assess quality (low, moderate, high) and the risk of bias (low, moderate, high) was performed by two authors (KW, SJ), and interrater reliability was calculated using Cohen’s kappa. In cases of different ratings, a third rater (JK) evaluated the study. For analysis of implant survival, descriptive data were extracted from the identified studies with regard to the level of evidence and reported follow-up time frames. The number of implants placed in all relevant studies and the number of successfully incorporated implants in function at the end of the observation period (survived implants) were calculated. Success rates were determined by dividing the number of surviving implants by the total number of implants placed. Because of the heterogeneity of the studies, a metaanalysis or analytic statistics could not be performed.
Results Of 90 published clinical studies and case reports, 49 articles met the authors’ requirements and were included for further analysis. Table 2 summarizes these 49 The International Journal of Oral & Maxillofacial Implants 385
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Wermker et al
Table 1 Levels of Evidence According to the Oxford Centre for Evidence-Based Medicine27
Table 2 Evidence Level of Studies Included in This Review
Level of evidence
EbM level27
Characteristics
1a 1b
Systematic review of randomized controlled trials Randomized controlled trial
2a 2b 2c
Systematic review of cohort studies Prospective cohort study “Outcomes” research
3a 3b
Systematic review of case-control studies Case-control study
4
Case series/case reports
5
Expert opinion
No. of studies [references] Retrospective
Prospective
Total
1b
0
0
0
1c
0
0
0
2b
0
16
1
2c
128
0
1
3b
1220–22,29–37
938–46
4
2612,17,18,47,54–75
0
26
Total
39
10
49
21
Reprinted with permission from University of Oxford, Centre for EvidenceBased Medicine.
publications in context with their evidence level and with regard to their design (prospective or retrospective). Only 18 articles presented survival rates of dental implants in cleft patients. The other 31 articles were case series or case reports with low levels of evidence.
Survival Rates of Dental Implants in Cleft Lip and Palate Patients
Table 3 summarizes the clinical studies that investigated the survival rates of dental implants in patients with clefts. This list of identified studies dealing with implant survival in cleft patients is ordered according to the evidence level and, within each evidence level, according to reported follow-up or observation time, beginning with the shortest. Interrater reliability was good for quality assessment (Cohen’s kappa = 0.700) and risk of bias assessment (Cohen’s kappa = 0.833). In these 18 studies, 670 implants in 460 cleft patients were analyzed for implant survival. The accumulated descriptive data in different time frames (without considering different levels of evidence of the studies) produced a 2-year survival rate of 89.2% (74 implants in 61 patients; two studies); a 3-year survival rate of 94.1% (265 implants in 183 patients; seven studies); and a 5-year survival rate of 88.6% (268 implants in 166 patients; six studies). With regard to the EbM level, the majority of the publications were characterized as evidence level 3b, ie, case-control studies. This reflects the absence of control groups and the retrospective design of the studies. One research group prospectively analyzed implant survival after maxillary bone grafting, comparing cleft patients to a group of patients after maxillary trauma and consecutive loss of anterior alveolar crest, with a follow-up period of 48 months.6 The survival rates, analyzed by Kaplan-Meier, did not show statistically significant differences: The 1- and 5-year survival rates
were 84% (80% in cleft patients; n= 20) and 89% (88% in the trauma group; n = 20), respectively. Secondary parameters, such as bone loss, gingival recession, or peri-implant probing depths, also showed no significant differences. To sum up the data, the survival rates of dental implants according to the listed data ranged from 86.7% to 96.7% over 3 years. The 5-year survival rates hovered between 80% and 98.6%. The study with the longest observation period (16 years) reported a 71% rate of functional successful dental implants as single-tooth replacements in cleft patients.29 This study was included in the analysis because of the exceptionally long follow-up time, although, because of the study design, assessment of the EbM level was not possible.
Optimal Date for Implant Insertion in Cleft Patients
Concerning the ideal age for implant insertion, there seems to be a consensus that, in cleft patients, dental implants should be placed after growth is complete. In only 1 of the 49 included publications (Table 2) implant placement in the growing skull in a 10-year-old cleft patient was reported.18 All other authors favored implant insertion after adolescence, when growth was finished. The time interval between secondary bone grafting (at the age of 8 to 11 years) and implant placement was not systematically reported in the analyzed studies. In one prospective study, the mean interval in nine patients was 57 months.30 Other studies did not report time intervals sufficiently to enable calculation of summary data. Fourteen publications analyzed the time between tertiary bone grafting and implant insertion. Most authors (eight studies) found that a time interval of 4 to 6 months was most suitable to avoid major bone resorption (and a consequent need for regrafting) and
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Wermker et al
Table 3 Patient, Implant, and Outcome Data and Quality of Evidence from Clinical Studies Presenting Survival Rates of Endosseous Dental Implants in Patients with Clefts Year of publication
Reference
EbM level27
No. of patients
No. of implants
Survival rate (%)
Follow-up time (y)
Quality
Risk of bias
Landes6
2006
2b
20
25
80.0
5
H
L
Duskova et al41
2007
3b
45
45
86.7
2
M
M
Lilja et al45
1998
3b
16
29
93.0
2
M
M
al30
2012
3b
17
24
95.8
3
M
M
De Barros Ferreira32
2010
3b
120
123
94.3
3
H
M
Härtel et al22
1999
3b
11
17
96.0
3
M
M
Jansma et al31
1999
3b
10
31
96.7
3
M
M
Kearns et al38
1997
3b
14
29
90.0
3
M
M M
Landes et
al34
1994
3b
6
23
91.0
3
M
Jensen et al33
1998
3b
16
20
90.0
4
M
M
Lalo et al44
2007
3b
12
12
91.7
5
M
M
Matsui et al40
2007
3b
47
71
98.6
5
M
M
Kramer et al43
2005
3b
45
75
82.2
5
M
M
Deppe et al21
2004
3b
32
35
91.4
5
M
M
Laine et al37
2002
3b
10
50
85.7
5
M
M
Takahashi et al39
2008
3b
16
21
90.9
6
M
M
Arcuri etl
al64
2010
4
5
18
94.4
3
L
H
Krieger et al29
2009
-*
18
22
71.0
16
M
H
Sándor et
Study quality, risk of bias assessment: L = low, M = moderate, H = high. *Assessment of EbM level not applicable because of study design (analysis of insurance data).
to place implants in the alveolar cleft area with the lowest complication rates.19,20,31,32,38–40,70 Two studies presented unfavorable results of up to 43% disturbed wound healing and up to 86% partial bone loss for simultaneous tertiary bone grafting and implant insertion.33,47 Two studies also analyzed and proposed shorter time intervals of 1.5 to 2 months and 3 months, respectively.22,71 In two studies, longer periods of 6 to 12 and 6 to 13 months between tertiary bone grafting and implantation were analyzed; neither was associated with a greater need for regrafting.6,17
Discussion When the relevant literature dealing with implant placement in cleft patients is evaluated, the low level of evidence becomes obvious. There is currently only one study that prospectively investigated the survival rates and the relevant prognostic factors of dental implants in patients with clefts after bone grafting on the one hand and patients after maxillary trauma and bony augmentation on the other hand, reaching an EbM level of 2b.6 The others are case-control studies, which retrospectively investigated different patient populations, matching evidence levels 3b or 4 (case series and case reports). To date, the data must be re-
garded as insufficient, with a lack of prospective clinical trials with a representative number of subjects and defined control groups. Regarding the study of cleft patients, the requirements of evidence-based medicine are hard to meet. One reason is the incidence of cleft alveolus and palate; with a rate of 1:500 to 1:700, cleft patients are not incredibly common. Furthermore, in the analysis of the growing skull, observation periods of several years are sought to achieve significant results comparing therapies, risks, and outcomes. A clean randomized trial seems scarcely viable simply because of ethical considerations, so a level 1 study will not be realizable. Another challenge in designing a study dealing with patients with cleft lip, alveolus, and palate is the implementation of an apt control group. General possibilities and limitations in the analysis and evaluation of therapeutic concepts in patients with cleft lip and palate were extensively discussed previously.72 Secondary bone grafting of the residual alveolar cleft during the mixed dentition years is currently the favored method to allow for physiologic and esthetic rehabilitation.1,7–10 Placement of endosseous dental implants in the growing jaw is generally not recommended,23–26 with the exception of one study, which reported good results when implants were placed before the growth spurt.18 The International Journal of Oral & Maxillofacial Implants 387
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Wermker et al
The clinical challenge resides in the management of the time lag between bone grafting and implant placement. Wound and bone healing and remodeling are pitted against atrophy and loss of bone height. To prevent excessive atrophy, a physiologic functional strain on the bone is mandatory.73 With this in mind, the optimal timing for implant placement would be 3 to 6 months after bone grafting, as recommended by most authors, with a range from 2 to 12 months.17,22,70,71 This broad range is another result of the lack of evidence/ data. Short-term implant insertion at a 6-month interval can be easily performed after tertiary bone grafting without interfering with the growth of the jaw, but this cannot be done after secondary bone grafting. Therefore, in most cases after secondary bone grafting, an additional surgery for augmentative bone grafting (regrafting) is necessary before implant placement. Subsequently, early implant insertion and loading is recommended.6 Systematic reviews have reported a 97% survival rate at 7 years for implants used for single-tooth replacement in native bone.13,14 The reported 5-year survival rates of implants in the area of an alveolar cleft after bone grafting range from 80% to 96%, with a mean of 88.6%.6,17,18,32,39,74 A prospective study found a 5-year survival rate of 80% in a group of cleft patients, compared to 88% survival in the control group of posttraumatic augmentation and implantation patients, by Kaplan-Meier analysis; the difference was not significant.6 To the authors’ knowledge, this is the first systematic review to analyze the survival rates of dental implants in cleft patients. Concerning the optimal date of implant placement, only one other review also analyzed this question and reached similar conclusions.75 It has to be kept in mind that this review, with the exception of one prospective study, summarized retrospective data exclusively. A retrospective study design means that the risk of selection bias (eg, concerning patient selection, consistency of compared groups and therapies) is higher and the quality of the data is lower in comparison to a prospectively designed study. Another weakness of this systematic review is the fact that, because of the heterogenous designs of the studies and different quality of reported data in the analyzed studies, it was not possible to generate a high-quality summary of the data. It was possible to sum up the data only in a descriptive manner; statistics such as forest plots, summarized Kaplan-Meier survival analysis, or even a meta-analysis were not feasible. For the successful dental rehabilitation of patients with cleft lip, alveolus, and palate, secondary bone grafting of the jaw with an autologous bone graft from the hip at the age of 8 to 11 years during the mixed dentition, combined with implant placement after
growth is complete, is the most efficient and favored method. Nevertheless, in most of these cases, further bony augmentation before inserting dental implants 4 to 6 months later is necessary. With 5-year survival rates up to and above 90%, the insertion of endosseous implants represents a reliable procedure for oral rehabilitation in cleft patients, with a good long-term prognosis. According to current clinical studies and data of this review, a 5-year survival rate above 88% can be expected. The therapeutic alternative is the orthodontic closure of the dental gap. Therefore, augmentative therapy is not necessary, but its striking disadvantage is the loss of the physiologic architecture of the dental arch, especially the positions of the canines, the asymmetric results in unilateral clefts, and the imminent root resorption after large orthodontic movements. The insertion of endosseous dental implants represents the most functional and esthetic means to restore the bony alveolar defect as well as the dental arch in patients with cleft lip and palate. Nevertheless, concerning dental replacement of missing teeth in cleft patients, the absence of evidence concerning some open questions is obvious. In general, to date, there is not enough evidence to determine whether replacing missing teeth with dental implants is more favorable than orthodontic gap closure regarding different parameters (eg, unilateral or bilateral missing teeth, number of missing teeth, type and extent of clefting, influence of different treatment concepts). Concerning insertion of dental implants in the area of the alveolar cleft, the influence of implant length and diameter has not been investigated sufficiently. Most retrospective studies presented survival rates of implants in a descriptive manner. Prospective clinical trials are needed to allow for adequate analysis of implant survival rates (eg, analysis according to Kaplan-Meier) and to subsequently enable pooling and adequate summing up of data. This would facilitate systematic reviews with higher statistical quality or a meta-analysis. Critically, it must be kept in mind that generating studies with high levels of evidence in cleft patients is more difficult than in other fields, as discussed previously.72
Conclusion Reported 5-year survival rates for dental implants in clefts range from 80% to 96% (mean, 88.6%). Implant placement is favored after completion of growth and is recommended in most cases within 4 to 6 months after bone grafting. The results suggest that dental implants allow for a sufficient functional and esthetic oral rehabilitation in patients with cleft lip and palate,
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although implant survival rates are lower in cleft patients than in noncleft subjects. This systematic review clearly highlights the lack of evidence concerning the placement of dental implants in cleft patients. More research, especially prospective clinical trials, is needed to broaden the database and clarify the remaining open questions.
Acknowledgments The authors declare that they have no competing interests. Author contributions: KW designed the study; KW, SJ, and JK drafted the manuscript; KW searched the relevant literature, and KW and SJ read the searched literature; KW and SJ performed data analysis; UJ gave important intellectual content to the study design; JK gave important content to the study design, revised the manuscript, and gave final approval to the version being published; all authors read and approved the final manuscript.
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