Clinical Outcomes of Dental Implant Therapy in Alveolar Cleft Patients: A Systematic Review Feng Wang, DDS, MS1/Yiqun Wu, DDS, PhD2/Duohong Zou, DDS, PhD3/ Guomin Wang, DDS, PhD4/Darnell Kaigler, DDS, MS, PhD5 Purpose: The purpose of this report was to evaluate data from published articles to determine the success and effectiveness of advanced bone grafting and dental implant therapy in alveolar cleft patients. Materials and Methods: A MEDLINE (PubMed) search was conducted of articles published in English without limits regarding year of publication. Bone grafting, implant survival and success rates, marginal bone resorption, esthetic outcomes, and patient satisfaction were evaluated. Screening of eligible studies, quality assessment, and data interpretation were conducted by two reviewers independently. Results: Seven retrospective and four prospective clinical studies were selected and analyzed. In all, 484 dental implants in 377 participants were investigated. The mean survival rate was 91.5% ± 4.77% with a mean follow-up of 54.3 ± 24.7 months. One hundred eleven of the 257 patients (43.1% ± 31.6%) with inadequate bone volume following initial bone grafting received secondary and/or tertiary bone grafting. The donor sites included the tibia, iliac crest, mandibular symphysis, and mandibular ramus. After dental implant placement, studies showed a difference in marginal bone loss around implants ranging from a mean of 0.28 mm with a 40-month follow-up to a mean of 3.5 mm with a 76-month follow-up. There were few data reporting the esthetic outcomes of implants; these focused on the loss of papillae and longer definitive restorations. Conclusion: Differing levels of evidence were available for clinical outcomes of dental implants in alveolar cleft patients. Treatment with dental implant therapy and bone grafting for patients with a history of alveolar clefts seems to be a predictable treatment option in the short term (< 5 years). However, more long-term (> 5 years) data for implant success rates and peri-implant clinical parameters are needed. Int J Oral Maxillofac Implants 2014;29:1098–1105. doi: 10.11607/jomi.3585 Key words: alveolar bone grafting, alveolar cleft, cleft lip and palate, dental implants, secondary alveolar bone grafting
C
left lip and palate is one of the most common congenital anomalies (with an incidence of 1.82/1,000 in China) and causes deformities that require multidisciplinary efforts for rehabilitation.1 Patients with alveolar cleft frequently exhibit congenital absence of the lateral incisor adjacent to the cleft.2–5 To accomplish space closure in the cleft area, secondary bone grafting (at the end of the mixed dentition, preferably before the eruption of the permanent canines)
combined with orthodontic therapy may be indicated.6 However, it is not possible to move the canine into a good position relative to the central incisor in 10% to 50% of cleft patients.7 In these patients, the lateral incisor site in the cleft area is often restored with a conventional fixed partial denture. This approach is not always optimal, especially in patients with intact neighboring teeth without caries lesions or existing fillings.8,9
1ITI
5Assistant
Scholar; Faculty, Department of Oral and Maxillofacial Implantology, Ninth People’s Hospital Affiliated with Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. 2Professor, Department of Oral and Maxillofacial Implantology, Ninth People’s Hospital Affiliated with Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. 3 Professor, Department of Oral Implant, Stomatologic Hospital and College, Anhui Medical University, Key Laboratory for Oral Diseases Research of Anhui Province, Hefei, China. 4Professor, Center for Cleft Lip and Palate, Department of Oral and Cranio-Maxillofacial Science, Ninth People’s Hospital Affiliated with Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
Professor, Department of Periodontics and Oral Medicine and Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; University of Michigan Center of Oral Health Research, Ann Arbor, Michigan.
Correspondence to: Darnell Kaigler, Department of Periodontics and Oral Medicine and Biomedical Engineering, University of Michigan, 1011 N. University, Ann Arbor, MI 48109, USA Email: [email protected] Guomin Wang, Center for Cleft Lip and Palate, Department of Oral and Cranio-Maxillofacial Science, Ninth People’s Hospital Affiliated with Shanghai Jiao Tong University, School of Medicine, No.639 Zhizaoju Road, Shanghai, 200011, China. Email: [email protected] ©2014 by Quintessence Publishing Co Inc.
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Wang et al
In 1991, Verdi et al10 first reported the use of implants to restore the edentulous alveolar cleft region. Implants were successfully placed 18 months following closure of the oronasal fistula and reconstruction of the alveolar cleft with autogenous cancellous bone.10 The concept of dental rehabilitation with dental implants has since emerged as a treatment option for patients with alveolar cleft.11–13 However, a prerequisite for implant placement is the presence of adequate volume and quality of bone within the cleft. As such, dental implant therapy for patients with a history of alveolar clefts is one of the most challenging problems for dentists because of the deficiency of hard and soft tissue and discontinuity of dental arch form. Secondary bone grafting of the alveolar cleft in the mixed dentition before canine eruption is a wellestablished procedure.14,15 The purpose of the procedure is to close the oronasal fistula and to allow the canine(s) to erupt in the cleft region(s) for orthodontic treatment.16,17 However, the optimal time for implant placement has been reported to be just after the growth spurt, because the implant behaves as an ankylosed tooth and may become submerged during the rapid growth phase of adolescence.18–20 As a result, there is usually a time lag between bone grafting and implant placement. The degree of graft resorption may be significant; thus, regrafting at the time of implant placement may be required to ensure good primary stability and ideal positioning of dental implants. Dental implants have been used to restore edentulous alveolar cleft sites for more than 20 years, but therapeutic success is contingent upon an adequate volume of bone at the defect site.21,22 Few comprehensive evaluations of bone grafting and implant therapy for these indications have been performed, and, to the authors’ knowledge, only one review has addressed the role of endosseous implants in the treatment of alveolar clefts.8 The present review was undertaken to evaluate the literature on this topic to determine whether dental implant therapy in combination with advanced alveolar bone grafting provides the desired outcome of successful therapy in patients with a history of alveolar cleft.
MATERIALS AND METHODS An electronic search of the PubMed (MEDLINE) database was performed with the intention of collecting relevant information about the clinical performance of dental implants in alveolar cleft patients. No limits were placed regarding the year of publication. The search was limited to studies in English and was performed by two independent reviewers using the terms “dental,” “implant,” “implants,” “alveolar,” and “cleft.”
Every search was complemented by manual searches of the reference lists of all selected full-text articles.
Inclusion and Exclusion Criteria
The inclusion criteria were as follows: • Human clinical study • Studies specifically designed to investigate dental implants in alveolar cleft areas • Use of root-form or cylindric titanium implants with machined or modified surfaces • A sample size of at least 10 patients • To enable the evaluation of implant and prosthetic survival, success, and complication rates, a minimum follow-up time of 12 months after functional loading of the implants placed in the cleft region • Reported treatment outcomes that included at least one of the following parameters: clinical, radiographic, esthetic, or patient-centered outcomes • Only the most inclusive publication from a case series for which the same data had been published on multiple occasions Studies not meeting all inclusion criteria were excluded from the review. Also excluded from the analysis were case reports and case series reports with fewer than 10 patients.
Data Extraction
Two reviewers evaluated the data independently using data extraction tables. The data extracted included the year of publication, the type of study, the aim of the study, the number of patients enrolled, the number and types of implants used, the surgical technique used, the follow-up period, the survival rate, the success rate, esthetic outcomes, measures of patient satisfaction, and complications.
Data Analysis
Agreement between reviewers was calculated by Cohen κ statistical analysis. The mean follow-up period of the selected reports was calculated as the weighted mean on the number of implants investigated at each stage of the study. Data were presented on the implant level. The statistical analysis was performed with SPSS for Windows (release 19.0, standard version; SPSS).
RESULTS Study Selection and Data Extraction
The electronic and manual searches identified 84 articles. Following analysis of the titles and abstracts, 47 articles were excluded, leaving only 37 articles for possible inclusion based on the titles. After the inclusion The International Journal of Oral & Maxillofacial Implants 1099
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Wang et al
Initial electronic search: 84 titles Excluded articles: 3 reports focusing on bone reconstruction 1 report focusing on keratinized mucosa around implants 1 report with duplicate publication by same author
Independently selected by two reviewers: 37 titles
Discussion, agreement on 16 abstracts: full text obtained
Full-text analysis; studies included: 11
Fig 1 Flowchart of article selection process.
criteria were applied to the abstracts, 16 articles were deemed suitable for full-text analysis. Of these, 11 articles were found to be acceptable for inclusion. Therefore, 11 articles were considered acceptable for the systematic review (Fig 1).21–31
Study Quality
The criteria for treatment success varied. Implant osseointegration periods, implant characteristics, and follow-up periods varied considerably within the same studies and between different studies. The quality of included studies was not comparative in nature, without a high level of evidence, and the search failed to reveal any randomized controlled clinical trials. The 11 eligible publications included a total of 7 retrospective and 4 prospective clinical studies. Most papers reported the number of implants monitored at each stage of the study, and two papers explained the number of dropouts (both patients and implants).23,24
Patient Selection
The data extracted from the studies included in the review are summarized below (Table 1). In total, 377 patients were treated; their ages ranged from 8 to 66 years (mean age, 21.3 years). Ten articles reported the participants’ sex, and all 11 articles reported the cleft type. Of 345 patients reported in 10 articles, there were 181 male and 164 female patients. There were 285 patients with unilateral alveolar cleft and 76 patients with bilateral alveolar clefts in 11 articles.
Surgical Procedures
Nine of the 11 articles reported the number of patients who received secondary or tertiary bone grafting. Most patients (98.4%; 95% confidence interval [CI], 95.6% to 100%) in the study underwent bone grafting at an earlier age, and the most common donor site was the ilium. Among the articles, only one paper reported
a single-stage surgical technique, which combined chin bone grafting and simultaneous implant placement.25 Six papers showed a mean interval of 47.8 ± 34.0 months (95% CI, 20.4 to 72.7 months) between secondary or tertiary bone grafting and implant placement. All papers with staged implant placement reported regrafting procedures before implant placement, and 9 papers reported the exact number of patients who received regrafting. A total of 111 of 257 patients (43.1% ± 31.6%) (95% CI, 23.0% to 63.8%) with inadequate bone volume underwent regrafting after secondary or tertiary bone grafting (Table 2). Donor sites for bone grafts included the tibia, iliac crest, mandibular symphysis, and mandibular ramus.
Implant Characteristics
Four hundred eighty-four implants were inserted in alveolar cleft areas after bone grafting. The reported implant lengths varied from 8.5 to 20 mm, and the implant diameters ranged from 3.0 to 4.1 mm with different implant brands. However, some studies reported only the length or diameter of the implants placed. Implant surface characteristics were reported in four articles and varied between studies.21,22,24,26
Survival and Success Rates
To determine implant “survival” and “success” based on the follow-up periods, two studies reported followup periods from both the time of implant insertion and prosthetic loading,27,28 four studies established baseline as the time of implant insertion,23,25,26,29 two studies established prosthetic loading as baseline,21,30 and the other three did not explain how this was determined.16,18,25 A total of five patients with seven implants dropped out during the follow-up period in two studies.23,24 The mean implant survival rate was reported in all but one study, and was 91.5% ± 4.77% (95% CI, 88.4% to 94.1%) with a mean follow-up period of 54.3 ± 24.7 months (95% CI, 39.7 to 69.4 months). An analysis of cumulative success rate (CSR) according to Kaplan-Meier at follow-up was reported in only two studies. Kramer et al21 reported an 82.2% CSR after 66 months of follow-up and Matsui et al22 reported a CSR of 98.6% at 60 months. Both of the studies reported the same CSR at the end of the first year and at the end of the observation period. One paper26 reported a CSR of dental implants of 95.8% after 40 months of follow-up, according to the Buser et al 1990 definition of success.32
Marginal Bone Loss
Six articles reported on marginal bone loss (MBL) during the follow-up period.22–26,29 Five of these six papers reported quantitative data, and one paper reported MBL as the percentage of implant length exposed. In one study, MBL of 1.5 mm occurred during the first
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Table 1 Study Design, Participants, Interventions, Outcomes, and Main Findings of the Selected Studies
Study
Study No. of design patients
Type of cleft
Mean age (range) (y)
Mean Implant Implant follow-up length diameter No. of Prosthesis (range) (mm) (mm) implants design (mo)
Implant type
Kearns et al (1997)27
R
14
Uni 9, Bi 5
22.2 3i (Biomet (15–66) 3i)
10
Jensen et al (1998)25
R
16
Uni 14, Bi 2
19 Brånemark (15–38) (Nobel Biocare)
Lilja et al (1998)30
R
16
CLP 10, CL 6
Härtel et al (1999)23
R
15
Deppe et al (2004)29
R
NR
10–20 NR
20
Single 48 crowns, (36–69) fused crown
90%
23.7 Brånemark (16–53)
10–15 NR
31
NR
66 (43–92)
93%
Uni 8, Bi 7
17 Straumann (14–27)
10–16 3.0, 3.3, 4.0
23
Single crown
28 (4–36)
94%
32
Uni 29, Bi 3
17.5 (8–28)
IMZ (NR), Friadent (Dentsply)
35
NR
76 (6–122)
86.2%
Kramer et al (2005)21
P
45
Uni 24, Bi 21
25.9 (14.8– 49.1)
Brånemark
75
Single 66 82.2% crown, FPD, (18–136) bar-based overdenture
Matsui et al (2007)22
P
47
Uni 32, Bi 15
23.3 (14.6– 54.6)
Brånemark, 10–15 3.25, 3i, Zimmer 3.75, (Calcitek), 3.8, 4.0 GC (GC), AFC (Asahi Optical)
71
Single crown, FPD
de Barros Ferreira et al (2010)28
R
120
Uni 106, Bi 7
21 NR (15–40)
8.5–15 3.3, 3.75, 4.0
Landes et al (2012)26
P
17
Uni 14, Bi 3
24 Straumann (15–36)
10–12 3.3, 4.1
24
Single crown
Takahashi et al (2008)24
R
16
Uni 13, Bi 3
19.1 (13.9– 33.6)
Brånemark
10–18 3.75
23
Single crown
Filho and Almeida (2013)31
P
39
Uni 39
19–23
NR
39
Single crown
NR
10–15 3.3, 3.75
8–17
3.3, 3.75, 4.0
123
NR
28.5 (1–47)
ISR
20
NR
3.3, 4.0
90%
60 98.6% (12–120)
26 (NR)
94.3%
40 (6–89)
95.8%
103 90.9% (86–113) 42 (NR)
NR
R = retrospective; P = prospective; ISR = implant survival rate; Bi = bilateral; Uni = unilateral; CLP = cleft lip and palate; CL = cleft lip only; FPD = fixed partial denture; NR = not reported.
year of loading, and bone levels stabilized thereafter.25 Three studies showed mean MBL of 0.28 ± 0.15 mm, 1.15 ± 2.16 mm, and 3.5 mm at 72 months, 40 months, and 76 months, respectively.24,26,29 One study22 evaluated MBL around hydroxyapatite-coated, smooth, and rough-surfaced implants. The mean MBLs around the hydroxyapatite-coated implants (2.8 mm at 41.4 months) and the smooth-surface implants (1.6 mm at 35.1 months) were largely stable throughout the follow-up period compared to the MBL seen around the rough-surface implants (3.17 mm at 18.2 months).22 Another study reported that 30% of implants (5 of 17) were incompletely surrounded by bone in the crestal region, as evaluated on radiographs.23
Esthetic Outcomes and Patient Satisfaction
Implant esthetic outcomes were evaluated in only two studies.26,31 Landes et al assessed patients with color photographs using an implant crown esthetic index and found that both patients and nondental professionals rated the soft tissue esthetics worse than the esthetics of implant-supported single crowns in noncleft patients.26 Filho et al measured clinical crown lengths and calculated papilla scores to compare the dental implants in alveolar cleft areas to the contralateral tooth.31 The implant-supported prosthetic crowns were longer than the contralateral tooth and, among the 78 papillae analyzed, 63% did not completely fill the interproximal space.31 Only one article26 used The International Journal of Oral & Maxillofacial Implants 1101
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Table 2 Characteristics of Bone Grafting of Patients in the Selected Studies Secondary/tertiary bone grafting data Study
No. of patients
Donor site
No. of patients
Interval between grafting and implant placement (mean, range) (mo)
Regrafting data Performed?
Donor site
No. of patients 5
Kearns et al (1997)27
14
Ilium
14
20.5, 4–46
Yes
Chin or iliac crest
Jensen et al (1998)25
16
Chin
16
Simultaneous
No
–
–
Lilja et al (1998)30
16
NR
14
NR
Yes
Tibia
Härtel et al (1999)23
15
Ilium
15
NR
Yes
Chin or iliac crest
9
Deppe et al (2004)29
32
NR
32
57.6, 4–108
Yes
Intraoral bone or iliac crest
9
Kramer et al (2005)21
45
Ilium
45
Simultaneous or delayed
Yes
NR
6
Matsui et al (2007)22
47
NR
47
NR
Yes
Ilium or intraoral bone
47
120
NR
NR
NR
Yes
NR
NR
de Barros Ferreira et al (2010)28
10
Landes et al (2012)26
17
Ilium and mandibular angle
17
Simultaneous or delayed; Secondary: 93, 78–114 Tertiary: 8, 0–26
Yes
NR
1
Takahashi et al (2008)24
16
Ilium
16
60, 16.8–122
Yes
Chin
5
Filho and Almeida (2013)31
39
Ilium
NR
NR
Yes
Mandibular ramus
19
NR = not reported.
the Oral Health Impact Profile (OHIP-G14) to subjectively assess treatment outcomes. A high level of oralhealth–related quality of life was obtained, which was found to be similar to that observed in the treatment of noncleft patients.26 The implant therapy for one cleft case is illustrated in Figs 2a to 2l.
DISCUSSION The present systematic review sought to evaluate the clinical outcomes of dental implants placed in grafted sites of patients with a history of alveolar clefting. Although the included studies provide the best available evidence, they have multiple inherent limitations that place the results at a greater risk of bias. For example, only retrospective and prospective cohort studies met the criteria for this review; no randomized controlled studies have been published. Further, the selected articles presented with heterogeneity regarding study design, sample size, implant type, and parameters for outcome measures.
Bone Graft and Implant Placement
Secondary bone grafting of alveolar clefts in the mixed dentition before canine eruption is a well-established procedure.3 Most patients (98.4%) in the study
underwent bone grafting at an early age, during the mixed dentition or later. However, nearly half of these patients had inadequate bone volume when implant placement was indicated and thus needed regrafting prior to dental implant placement. Intraoral donor sources of the grafts included the mandibular symphysis and ramus, and these are acceptable sources of donor bone when a relatively small amount of bone is required. However, if a larger volume of bone is necessary, the anterior iliac crest is the suggested donor site. Because a high percentage of alveolar cleft patients require regrafting, imaging using cone beam computed tomography is suggested to assist in surgical and prosthetic planning for implant therapy. Jensen et al tried to decrease graft resorption by simultaneously placing implants with mandibular bone grafts for secondary grafting of alveolar cleft defects; however, a high rate of wound dehiscence (25%) was recorded.25 Because of the extreme stretching of the flap required to cover the onlay bone graft, a two-stage procedure has been recommended by many authors, with regrafting being performed at various time intervals prior to implant placement. Some authors believe that the longer the interval, the greater the likelihood of alveolar bone resorption.27,29 However, reports vary on the optimal time between regrafting and implant insertion. Some clinical observations have shown that the optimal
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Figs 2a to 2d Images of a 19-year-old female patient with unilateral cleft lip and alveolus with missing right lateral incisor, 4 years after secondary iliac bone grafting and orthodontic treatment.
a
b
c
d
e
f
h
i
Figs 2e to 2i Implant placement with simultaneous guided bone regeneration.
g
Fig 2j Frontal view of implant-supported prosthesis.
Fig 2k Appearance of the patient showing the low smile line.
Fig 2l Radiograph of prosthesis at 1-year follow-up.
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Wang et al
interval between bone grafting and implant placement should be 3 to 6 months.21,23,27 One study recommended that this period not exceed 6 to 8 weeks, because resorption of the bone graft accelerated greatly after this point.24
Implant Survival and Success Rates
Although some studies in the present review reported long-term “success rates” of implants, success rates did not take into account all the factors that clinicians and patients consider when evaluating successful outcomes (ie, function, esthetics, and inflammation). Instead, the “success rate” was described merely as the percentage of implants still in function without failure.23,30 Thus, the success rates reported for implants in these studies should more appropriately be considered survival rates or “successfully osseointegrated implants.” Only one study25 used an accepted definition of success32 and reported a cumulative success rate of dental implants in the alveolar cleft area of 95.8%. In the short-term evidence (< 5 years), the survival rate of dental implants was 91.5% ± 4.77%, indicating that this is a predictable treatment option for patients with a history of alveolar clefts. However, only six papers calculated progressive MBL around implants, and only five described quantitative data of bone loss observed.22–26,29 Moreover, it was difficult to compare the longitudinal data gathered from the selected studies, since some defined baseline as implant insertion, while others considered the time of prosthetic loading as baseline, resulting in much variability among studies. Two studies showed optimal results, with limited bone resorption of 1.15 ± 2.16 mm and 0.28 ± 0.15 mm at 40 months and 72 months, respectively.24,26 During the postloading period, regardless of time frame, three reports claimed that loading of endosseous implants with normal functional stresses was helpful in maintenance of the alveolar bone volume.24,26,27 One long-term follow-up study24 found that interdental alveolar bone height did not change after implant placement, also suggesting that the implants placed in the grafted alveoli maintained the alveolar bone height in the region. However, there was no other evidence or explicit data to directly support these claims.24 Kramer et al21 tried to evaluate the potential risk factors for implant failure in a long-term follow-up study. They found that the patient-related parameters of age, sex, and cleft type had no significant impact on success, but implant length was significantly related to an improved survival rate. Implant lengths of 13 mm or more resulted in significantly enhanced survival rates (93.1%) in comparison to shorter implants (62.1%). In the study of Takahashi et al,24 2 of 19 implants failed, with both being 7 mm long; the other implants in this study ranged from 10 to 18 mm in length. Thus,
the authors suggested that implants placed in grafted alveolar cleft defects should be at least 10 mm long. Matsui et al22 attributed a high survival rate (98.6%) to the use of implants longer than 13 mm in almost all cases. However, in the study of Kramer et al, more than half the patients (24 of 45) received machined-surface implants. There is a significant lack of information regarding esthetic outcomes in cleft patients compared with those achieved with conventional fixed prosthodontics and implant-supported restorations in patients without a history of alveolar clefts.35 Lilja et al30 pointed out that in grafted cleft defect sites, it is more difficult to achieve ideal positioning of the implant, and sometimes a more palatal position had to be used after additional bone grafting; this in turn, can compromise esthetics. Härtel et al found that angled implant positions and less-than-ideal angulation were observed when minimal bone was available.23 The crestal bone height at the site of the implant determines the vertical prosthetic crown length. An analysis of esthetic results, such as buccal mucosal recession or loss of interdental papillae of implants in the alveolar cleft area, was reported in only one study included in this review.26 The study demonstrated papilla shortening or loss and longer definitive crown length compared to the contralateral tooth and conventional implant-supported crowns. However, these esthetic compromises may be hidden in many cases; because more than half of the patients with alveolar clefts had a limited lip elevation, the gingival soft tissues were not displayed when talking or smiling.34 In the present review, no studies evaluated the restorative or biologic results, such as the occurrence of restorative complications or periimplant diseases of dental implants, in alveolar cleft grafting areas.
CONCLUSION Within the limitations of the small number of studies included in the present review, the following statements can be made. 1. One-stage procedures combining bone grafting and implant placement may not be optimal in alveolar cleft defects because of the high complication rates. 2. Four hundred eighty-four dental implants in 377 participants were investigated. Nearly half of the patients required regrafting before implant insertion; intraoral sources including the mandibular symphysis and ramus may provide predictable sources of donor bone when a relatively small volume of bone is required.
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3. The survival rate of dental implants was 91.5% ± 4.77%, indicating that this is a reliable treatment option for alveolar patients in the short term (< 5 years). However, a great deal of variation in marginal bone loss was observed among studies. 4. The esthetic outcomes of implant therapy have not been comprehensively evaluated in patients with a history of alveolar clefts. The limited studies reporting these parameters cited papilla shortening or loss and a longer definitive crown length as esthetic drawbacks. 5. Randomized controlled clinical trials and prospective studies with longer follow-up time and larger samples are necessary to evaluate the criteria for implant survival and success and peri-implant clinical parameters to validate the current findings.
ACKNOWLEDGMENTS This study was funded by the National Natural Science Foundation of China (81070813, 81100788, 31370983, 81371190), Science and Technology Commission of Shanghai Municipality (13ZR1424000), the Combined Engineering and Medical Project of Shanghai Jiao Tong University (YG2012MS32), the Key Project of Chinese Ministry of Education (212080), Grants for Scientific Research of BSKY (XJ201109), and the Young Top-notch Talent Support Scheme from Anhui Medical University. The authors reported no conflicts of interest related to this study.
REFERENCES 1. Xiao KZ. Epidemiogy of cleft lip and cleft palate in China. Zhonghua Yi Xue Za Zhi 1989;69:192–194. 2. Boyne PJ, Sands NR. Secondary bone grafting of residual alveolar and palate clefts. J Oral Surg 1972;30:87–92. 3. Abyholm FE, Bergland O, Semb G. Secondary bone grafting of alveolar clefts. Scand J Plast Reconstr Surg 1981;15:127–140. 4. Huebener DV, Liu JR. Advances in management of cleft lip and palate. Clin Plast Surg 1993;20:723–732. 5. Oberoi S, Vargervik K. Hypoplasia and hypodontia in Van der Woude syndrome. Cleft Palate Craniofac J 2005;42:459–466. 6. Bergland O, Semb G, Abyholm FE. Elimination of the residual alveolar cleft by secondary bone grafting and subsequent orthodontic treatment. Cleft Palate J 1986;23:175–205. 7. Ronchi P, Chiapasco M, Frattini D. Endosseous implants for prosthetic rehabilitation in bone grafted alveolar clefts. J Craniomaxillofac Surg 1995;23:382–386. 8. Pena WA, Vargervik K, Sharma A, Oberoi S. The role of endosseous implants in the management of alveolar clefts. Pediatric Dent 2009;31(4):329–333. 9. Jansma J, Raghoebar GM, Batenburg RH, Stellingsma C, van Oort RP. Bone grafting of cleft lip and palate patients for placement of endosseous implants. Cleft Palate Craniofac J 1999;36:67–72. 10. Verdi FJ Jr, Lanzi GL, Cohen SR, Powell R. Use of the Brånemark implant in the cleft palate patient. Cleft Palate Craniofac J 1991;28(3):301–303. 11. 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;18:630–638. 12. 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;48:98–102.
13. Sawakia M, Ueno T, Kagawa T, et al. Dental implant treatment for a patient with bilateral cleft lip and palate. Acta Med Okayama 2008;62:59–62. 14. Kawakami S, Yokozeki M, Horiuchi S, Moriyama K. Oral rehabilitation of an orthodontic patient with cleft lip and palate and hypodontia using secondary bone grafting, osseo-integrated implants, and prosthetic treatment. Cleft Palate Craniofac J 2004;41:279–284. 15. Dempf R, Teltzrow T, Kramer FJ, Hausamen JE. Alveolar bone grafting in patients with complete clefts: A comparative study between secondary and tertiary bone grafting. Cleft Palate Craniofac J 2002;39:18–25. 16. Lee S, Gantes B, Riggs M, Crigger M. Bone density assessments of dental implant sites: Bone quality evaluation during osteotomy and implant placement. Int J Oral Maxillofac Implants 2007;22:208–212. 17. Hogan L, Shand JM, Heggie AA, Kilpatrick N. Canine eruption into grafted alveolar clefts: A retrospective study. Aust Dent J 2003;48:119–124. 18. Sharma AB, Vargervik K. Using implants for the growing child. J Calif Dent Assoc 2006;31:719–724. 19. Bjork A, Skieller J. Growth of the maxilla in three dimensions as revealed radiographically by the implant method. Br J Orthod 1977;4:53–64. 20. Bjork A. Variations in the growth patterns of the human mandible: A longitudinal radiographic study by the implant method. J Dent Res 1963;42:400–411. 21. 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;34:715–721. 22. 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;44:444–447. 23. Härtel J, Pogl C, Henkel K, Cundlach K. Dental implants in alveolar cleft patients: A retrospective study. J Craniomaxllofac Surg 1999;27:354–357. 24. 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;105:297–302. 25. Jensen J, Sindet-Pedersen S, Enema H. Reconstruction of residual alveolar cleft defects with one-stage mandibular bone grafts and osseointegrated implants. J Oral Maxillofac Surg 1998;56:460–466. 26. Landes CA, Bündgen L, Laudemann K, Ghanaati S, Sader R. Patient satisfaction after prosthetic rehabilitation of bone-grafted alveolar clefts with nonsubmerged ITI Straumann dental implants loaded at three months. Cleft Palate Craniofac J 2012;49:601–608. 27. Kearns G, Perrott DH, Sharma A, Kaban LB, Vargervik K. Placement of endosseous implants in grafted alveolar clefts. Cleft Palate Craniofac J 1997;34:520–525. 28. de Barros Ferreira S, Esper LA, Sbrana MC, Ribeiro IW, de Almeida AL. Survival of dental implants in the cleft area—a retrospective study. Cleft Palate Craniofac J 2010;47:586–590. 29. Deppe H, Horch HH, Kolk A. Microstructured dental implants and palatal mucosal grafts in cleft patients: A retrospective analysis. J Craniomaxillofac Surg 2004;32:211–215. 30. 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;32:213–219. 31. Filho JF, Almeida AL. Aesthetic analysis of an implant-supported denture at the cleft area. Cleft Palate Craniofac J 2013 Sep;50:597–602. 32. Buser D, Weber HP, Lang NP. Tissue integration of non-submerged implants. 1-year results of a prospective study with 100 ITI hollow-cylinder and hollow-screw implants. Clin Oral Implants Res 1990;1:33–40. 33. Sindet-Pedersen S, Enemark H. Reconstruction of alveolar clefts with mandibular or iliac crest bone grafts: A comparative study. J Oral Maxillofac Surg 1990;48:554–558. 34. Takahashi T, Fukuda M, Yamaguchi T, Kochi S. Use of endosseous implants for dental reconstruction of patients with grafted alveolar clefts. J Oral Maxillofac Surg 1997;55:576–583. 35. Buser D, Martin W, Belser UC. Optimizing esthetics for implant restorations in the anterior maxilla: Anatomic and surgical considerations. Int J Oral Maxillofac Implants 2004;19(suppl):43–61.
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C
left lip and palate is one of the most common congenital anomalies (with an incidence of 1.82/1,000 in China) and causes deformities that require multidisciplinary efforts for rehabilitation.1 Patients with alveolar cleft frequently exhibit congenital absence of the lateral incisor adjacent to the cleft.2–5 To accomplish space closure in the cleft area, secondary bone grafting (at the end of the mixed dentition, preferably before the eruption of the permanent canines)
combined with orthodontic therapy may be indicated.6 However, it is not possible to move the canine into a good position relative to the central incisor in 10% to 50% of cleft patients.7 In these patients, the lateral incisor site in the cleft area is often restored with a conventional fixed partial denture. This approach is not always optimal, especially in patients with intact neighboring teeth without caries lesions or existing fillings.8,9
1ITI
5Assistant
Scholar; Faculty, Department of Oral and Maxillofacial Implantology, Ninth People’s Hospital Affiliated with Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. 2Professor, Department of Oral and Maxillofacial Implantology, Ninth People’s Hospital Affiliated with Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. 3 Professor, Department of Oral Implant, Stomatologic Hospital and College, Anhui Medical University, Key Laboratory for Oral Diseases Research of Anhui Province, Hefei, China. 4Professor, Center for Cleft Lip and Palate, Department of Oral and Cranio-Maxillofacial Science, Ninth People’s Hospital Affiliated with Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
Professor, Department of Periodontics and Oral Medicine and Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; University of Michigan Center of Oral Health Research, Ann Arbor, Michigan.
Correspondence to: Darnell Kaigler, Department of Periodontics and Oral Medicine and Biomedical Engineering, University of Michigan, 1011 N. University, Ann Arbor, MI 48109, USA Email: [email protected] Guomin Wang, Center for Cleft Lip and Palate, Department of Oral and Cranio-Maxillofacial Science, Ninth People’s Hospital Affiliated with Shanghai Jiao Tong University, School of Medicine, No.639 Zhizaoju Road, Shanghai, 200011, China. Email: [email protected] ©2014 by Quintessence Publishing Co Inc.
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Wang et al
In 1991, Verdi et al10 first reported the use of implants to restore the edentulous alveolar cleft region. Implants were successfully placed 18 months following closure of the oronasal fistula and reconstruction of the alveolar cleft with autogenous cancellous bone.10 The concept of dental rehabilitation with dental implants has since emerged as a treatment option for patients with alveolar cleft.11–13 However, a prerequisite for implant placement is the presence of adequate volume and quality of bone within the cleft. As such, dental implant therapy for patients with a history of alveolar clefts is one of the most challenging problems for dentists because of the deficiency of hard and soft tissue and discontinuity of dental arch form. Secondary bone grafting of the alveolar cleft in the mixed dentition before canine eruption is a wellestablished procedure.14,15 The purpose of the procedure is to close the oronasal fistula and to allow the canine(s) to erupt in the cleft region(s) for orthodontic treatment.16,17 However, the optimal time for implant placement has been reported to be just after the growth spurt, because the implant behaves as an ankylosed tooth and may become submerged during the rapid growth phase of adolescence.18–20 As a result, there is usually a time lag between bone grafting and implant placement. The degree of graft resorption may be significant; thus, regrafting at the time of implant placement may be required to ensure good primary stability and ideal positioning of dental implants. Dental implants have been used to restore edentulous alveolar cleft sites for more than 20 years, but therapeutic success is contingent upon an adequate volume of bone at the defect site.21,22 Few comprehensive evaluations of bone grafting and implant therapy for these indications have been performed, and, to the authors’ knowledge, only one review has addressed the role of endosseous implants in the treatment of alveolar clefts.8 The present review was undertaken to evaluate the literature on this topic to determine whether dental implant therapy in combination with advanced alveolar bone grafting provides the desired outcome of successful therapy in patients with a history of alveolar cleft.
MATERIALS AND METHODS An electronic search of the PubMed (MEDLINE) database was performed with the intention of collecting relevant information about the clinical performance of dental implants in alveolar cleft patients. No limits were placed regarding the year of publication. The search was limited to studies in English and was performed by two independent reviewers using the terms “dental,” “implant,” “implants,” “alveolar,” and “cleft.”
Every search was complemented by manual searches of the reference lists of all selected full-text articles.
Inclusion and Exclusion Criteria
The inclusion criteria were as follows: • Human clinical study • Studies specifically designed to investigate dental implants in alveolar cleft areas • Use of root-form or cylindric titanium implants with machined or modified surfaces • A sample size of at least 10 patients • To enable the evaluation of implant and prosthetic survival, success, and complication rates, a minimum follow-up time of 12 months after functional loading of the implants placed in the cleft region • Reported treatment outcomes that included at least one of the following parameters: clinical, radiographic, esthetic, or patient-centered outcomes • Only the most inclusive publication from a case series for which the same data had been published on multiple occasions Studies not meeting all inclusion criteria were excluded from the review. Also excluded from the analysis were case reports and case series reports with fewer than 10 patients.
Data Extraction
Two reviewers evaluated the data independently using data extraction tables. The data extracted included the year of publication, the type of study, the aim of the study, the number of patients enrolled, the number and types of implants used, the surgical technique used, the follow-up period, the survival rate, the success rate, esthetic outcomes, measures of patient satisfaction, and complications.
Data Analysis
Agreement between reviewers was calculated by Cohen κ statistical analysis. The mean follow-up period of the selected reports was calculated as the weighted mean on the number of implants investigated at each stage of the study. Data were presented on the implant level. The statistical analysis was performed with SPSS for Windows (release 19.0, standard version; SPSS).
RESULTS Study Selection and Data Extraction
The electronic and manual searches identified 84 articles. Following analysis of the titles and abstracts, 47 articles were excluded, leaving only 37 articles for possible inclusion based on the titles. After the inclusion The International Journal of Oral & Maxillofacial Implants 1099
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Wang et al
Initial electronic search: 84 titles Excluded articles: 3 reports focusing on bone reconstruction 1 report focusing on keratinized mucosa around implants 1 report with duplicate publication by same author
Independently selected by two reviewers: 37 titles
Discussion, agreement on 16 abstracts: full text obtained
Full-text analysis; studies included: 11
Fig 1 Flowchart of article selection process.
criteria were applied to the abstracts, 16 articles were deemed suitable for full-text analysis. Of these, 11 articles were found to be acceptable for inclusion. Therefore, 11 articles were considered acceptable for the systematic review (Fig 1).21–31
Study Quality
The criteria for treatment success varied. Implant osseointegration periods, implant characteristics, and follow-up periods varied considerably within the same studies and between different studies. The quality of included studies was not comparative in nature, without a high level of evidence, and the search failed to reveal any randomized controlled clinical trials. The 11 eligible publications included a total of 7 retrospective and 4 prospective clinical studies. Most papers reported the number of implants monitored at each stage of the study, and two papers explained the number of dropouts (both patients and implants).23,24
Patient Selection
The data extracted from the studies included in the review are summarized below (Table 1). In total, 377 patients were treated; their ages ranged from 8 to 66 years (mean age, 21.3 years). Ten articles reported the participants’ sex, and all 11 articles reported the cleft type. Of 345 patients reported in 10 articles, there were 181 male and 164 female patients. There were 285 patients with unilateral alveolar cleft and 76 patients with bilateral alveolar clefts in 11 articles.
Surgical Procedures
Nine of the 11 articles reported the number of patients who received secondary or tertiary bone grafting. Most patients (98.4%; 95% confidence interval [CI], 95.6% to 100%) in the study underwent bone grafting at an earlier age, and the most common donor site was the ilium. Among the articles, only one paper reported
a single-stage surgical technique, which combined chin bone grafting and simultaneous implant placement.25 Six papers showed a mean interval of 47.8 ± 34.0 months (95% CI, 20.4 to 72.7 months) between secondary or tertiary bone grafting and implant placement. All papers with staged implant placement reported regrafting procedures before implant placement, and 9 papers reported the exact number of patients who received regrafting. A total of 111 of 257 patients (43.1% ± 31.6%) (95% CI, 23.0% to 63.8%) with inadequate bone volume underwent regrafting after secondary or tertiary bone grafting (Table 2). Donor sites for bone grafts included the tibia, iliac crest, mandibular symphysis, and mandibular ramus.
Implant Characteristics
Four hundred eighty-four implants were inserted in alveolar cleft areas after bone grafting. The reported implant lengths varied from 8.5 to 20 mm, and the implant diameters ranged from 3.0 to 4.1 mm with different implant brands. However, some studies reported only the length or diameter of the implants placed. Implant surface characteristics were reported in four articles and varied between studies.21,22,24,26
Survival and Success Rates
To determine implant “survival” and “success” based on the follow-up periods, two studies reported followup periods from both the time of implant insertion and prosthetic loading,27,28 four studies established baseline as the time of implant insertion,23,25,26,29 two studies established prosthetic loading as baseline,21,30 and the other three did not explain how this was determined.16,18,25 A total of five patients with seven implants dropped out during the follow-up period in two studies.23,24 The mean implant survival rate was reported in all but one study, and was 91.5% ± 4.77% (95% CI, 88.4% to 94.1%) with a mean follow-up period of 54.3 ± 24.7 months (95% CI, 39.7 to 69.4 months). An analysis of cumulative success rate (CSR) according to Kaplan-Meier at follow-up was reported in only two studies. Kramer et al21 reported an 82.2% CSR after 66 months of follow-up and Matsui et al22 reported a CSR of 98.6% at 60 months. Both of the studies reported the same CSR at the end of the first year and at the end of the observation period. One paper26 reported a CSR of dental implants of 95.8% after 40 months of follow-up, according to the Buser et al 1990 definition of success.32
Marginal Bone Loss
Six articles reported on marginal bone loss (MBL) during the follow-up period.22–26,29 Five of these six papers reported quantitative data, and one paper reported MBL as the percentage of implant length exposed. In one study, MBL of 1.5 mm occurred during the first
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Wang et al
Table 1 Study Design, Participants, Interventions, Outcomes, and Main Findings of the Selected Studies
Study
Study No. of design patients
Type of cleft
Mean age (range) (y)
Mean Implant Implant follow-up length diameter No. of Prosthesis (range) (mm) (mm) implants design (mo)
Implant type
Kearns et al (1997)27
R
14
Uni 9, Bi 5
22.2 3i (Biomet (15–66) 3i)
10
Jensen et al (1998)25
R
16
Uni 14, Bi 2
19 Brånemark (15–38) (Nobel Biocare)
Lilja et al (1998)30
R
16
CLP 10, CL 6
Härtel et al (1999)23
R
15
Deppe et al (2004)29
R
NR
10–20 NR
20
Single 48 crowns, (36–69) fused crown
90%
23.7 Brånemark (16–53)
10–15 NR
31
NR
66 (43–92)
93%
Uni 8, Bi 7
17 Straumann (14–27)
10–16 3.0, 3.3, 4.0
23
Single crown
28 (4–36)
94%
32
Uni 29, Bi 3
17.5 (8–28)
IMZ (NR), Friadent (Dentsply)
35
NR
76 (6–122)
86.2%
Kramer et al (2005)21
P
45
Uni 24, Bi 21
25.9 (14.8– 49.1)
Brånemark
75
Single 66 82.2% crown, FPD, (18–136) bar-based overdenture
Matsui et al (2007)22
P
47
Uni 32, Bi 15
23.3 (14.6– 54.6)
Brånemark, 10–15 3.25, 3i, Zimmer 3.75, (Calcitek), 3.8, 4.0 GC (GC), AFC (Asahi Optical)
71
Single crown, FPD
de Barros Ferreira et al (2010)28
R
120
Uni 106, Bi 7
21 NR (15–40)
8.5–15 3.3, 3.75, 4.0
Landes et al (2012)26
P
17
Uni 14, Bi 3
24 Straumann (15–36)
10–12 3.3, 4.1
24
Single crown
Takahashi et al (2008)24
R
16
Uni 13, Bi 3
19.1 (13.9– 33.6)
Brånemark
10–18 3.75
23
Single crown
Filho and Almeida (2013)31
P
39
Uni 39
19–23
NR
39
Single crown
NR
10–15 3.3, 3.75
8–17
3.3, 3.75, 4.0
123
NR
28.5 (1–47)
ISR
20
NR
3.3, 4.0
90%
60 98.6% (12–120)
26 (NR)
94.3%
40 (6–89)
95.8%
103 90.9% (86–113) 42 (NR)
NR
R = retrospective; P = prospective; ISR = implant survival rate; Bi = bilateral; Uni = unilateral; CLP = cleft lip and palate; CL = cleft lip only; FPD = fixed partial denture; NR = not reported.
year of loading, and bone levels stabilized thereafter.25 Three studies showed mean MBL of 0.28 ± 0.15 mm, 1.15 ± 2.16 mm, and 3.5 mm at 72 months, 40 months, and 76 months, respectively.24,26,29 One study22 evaluated MBL around hydroxyapatite-coated, smooth, and rough-surfaced implants. The mean MBLs around the hydroxyapatite-coated implants (2.8 mm at 41.4 months) and the smooth-surface implants (1.6 mm at 35.1 months) were largely stable throughout the follow-up period compared to the MBL seen around the rough-surface implants (3.17 mm at 18.2 months).22 Another study reported that 30% of implants (5 of 17) were incompletely surrounded by bone in the crestal region, as evaluated on radiographs.23
Esthetic Outcomes and Patient Satisfaction
Implant esthetic outcomes were evaluated in only two studies.26,31 Landes et al assessed patients with color photographs using an implant crown esthetic index and found that both patients and nondental professionals rated the soft tissue esthetics worse than the esthetics of implant-supported single crowns in noncleft patients.26 Filho et al measured clinical crown lengths and calculated papilla scores to compare the dental implants in alveolar cleft areas to the contralateral tooth.31 The implant-supported prosthetic crowns were longer than the contralateral tooth and, among the 78 papillae analyzed, 63% did not completely fill the interproximal space.31 Only one article26 used The International Journal of Oral & Maxillofacial Implants 1101
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Wang et al
Table 2 Characteristics of Bone Grafting of Patients in the Selected Studies Secondary/tertiary bone grafting data Study
No. of patients
Donor site
No. of patients
Interval between grafting and implant placement (mean, range) (mo)
Regrafting data Performed?
Donor site
No. of patients 5
Kearns et al (1997)27
14
Ilium
14
20.5, 4–46
Yes
Chin or iliac crest
Jensen et al (1998)25
16
Chin
16
Simultaneous
No
–
–
Lilja et al (1998)30
16
NR
14
NR
Yes
Tibia
Härtel et al (1999)23
15
Ilium
15
NR
Yes
Chin or iliac crest
9
Deppe et al (2004)29
32
NR
32
57.6, 4–108
Yes
Intraoral bone or iliac crest
9
Kramer et al (2005)21
45
Ilium
45
Simultaneous or delayed
Yes
NR
6
Matsui et al (2007)22
47
NR
47
NR
Yes
Ilium or intraoral bone
47
120
NR
NR
NR
Yes
NR
NR
de Barros Ferreira et al (2010)28
10
Landes et al (2012)26
17
Ilium and mandibular angle
17
Simultaneous or delayed; Secondary: 93, 78–114 Tertiary: 8, 0–26
Yes
NR
1
Takahashi et al (2008)24
16
Ilium
16
60, 16.8–122
Yes
Chin
5
Filho and Almeida (2013)31
39
Ilium
NR
NR
Yes
Mandibular ramus
19
NR = not reported.
the Oral Health Impact Profile (OHIP-G14) to subjectively assess treatment outcomes. A high level of oralhealth–related quality of life was obtained, which was found to be similar to that observed in the treatment of noncleft patients.26 The implant therapy for one cleft case is illustrated in Figs 2a to 2l.
DISCUSSION The present systematic review sought to evaluate the clinical outcomes of dental implants placed in grafted sites of patients with a history of alveolar clefting. Although the included studies provide the best available evidence, they have multiple inherent limitations that place the results at a greater risk of bias. For example, only retrospective and prospective cohort studies met the criteria for this review; no randomized controlled studies have been published. Further, the selected articles presented with heterogeneity regarding study design, sample size, implant type, and parameters for outcome measures.
Bone Graft and Implant Placement
Secondary bone grafting of alveolar clefts in the mixed dentition before canine eruption is a well-established procedure.3 Most patients (98.4%) in the study
underwent bone grafting at an early age, during the mixed dentition or later. However, nearly half of these patients had inadequate bone volume when implant placement was indicated and thus needed regrafting prior to dental implant placement. Intraoral donor sources of the grafts included the mandibular symphysis and ramus, and these are acceptable sources of donor bone when a relatively small amount of bone is required. However, if a larger volume of bone is necessary, the anterior iliac crest is the suggested donor site. Because a high percentage of alveolar cleft patients require regrafting, imaging using cone beam computed tomography is suggested to assist in surgical and prosthetic planning for implant therapy. Jensen et al tried to decrease graft resorption by simultaneously placing implants with mandibular bone grafts for secondary grafting of alveolar cleft defects; however, a high rate of wound dehiscence (25%) was recorded.25 Because of the extreme stretching of the flap required to cover the onlay bone graft, a two-stage procedure has been recommended by many authors, with regrafting being performed at various time intervals prior to implant placement. Some authors believe that the longer the interval, the greater the likelihood of alveolar bone resorption.27,29 However, reports vary on the optimal time between regrafting and implant insertion. Some clinical observations have shown that the optimal
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Wang et al
Figs 2a to 2d Images of a 19-year-old female patient with unilateral cleft lip and alveolus with missing right lateral incisor, 4 years after secondary iliac bone grafting and orthodontic treatment.
a
b
c
d
e
f
h
i
Figs 2e to 2i Implant placement with simultaneous guided bone regeneration.
g
Fig 2j Frontal view of implant-supported prosthesis.
Fig 2k Appearance of the patient showing the low smile line.
Fig 2l Radiograph of prosthesis at 1-year follow-up.
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Wang et al
interval between bone grafting and implant placement should be 3 to 6 months.21,23,27 One study recommended that this period not exceed 6 to 8 weeks, because resorption of the bone graft accelerated greatly after this point.24
Implant Survival and Success Rates
Although some studies in the present review reported long-term “success rates” of implants, success rates did not take into account all the factors that clinicians and patients consider when evaluating successful outcomes (ie, function, esthetics, and inflammation). Instead, the “success rate” was described merely as the percentage of implants still in function without failure.23,30 Thus, the success rates reported for implants in these studies should more appropriately be considered survival rates or “successfully osseointegrated implants.” Only one study25 used an accepted definition of success32 and reported a cumulative success rate of dental implants in the alveolar cleft area of 95.8%. In the short-term evidence (< 5 years), the survival rate of dental implants was 91.5% ± 4.77%, indicating that this is a predictable treatment option for patients with a history of alveolar clefts. However, only six papers calculated progressive MBL around implants, and only five described quantitative data of bone loss observed.22–26,29 Moreover, it was difficult to compare the longitudinal data gathered from the selected studies, since some defined baseline as implant insertion, while others considered the time of prosthetic loading as baseline, resulting in much variability among studies. Two studies showed optimal results, with limited bone resorption of 1.15 ± 2.16 mm and 0.28 ± 0.15 mm at 40 months and 72 months, respectively.24,26 During the postloading period, regardless of time frame, three reports claimed that loading of endosseous implants with normal functional stresses was helpful in maintenance of the alveolar bone volume.24,26,27 One long-term follow-up study24 found that interdental alveolar bone height did not change after implant placement, also suggesting that the implants placed in the grafted alveoli maintained the alveolar bone height in the region. However, there was no other evidence or explicit data to directly support these claims.24 Kramer et al21 tried to evaluate the potential risk factors for implant failure in a long-term follow-up study. They found that the patient-related parameters of age, sex, and cleft type had no significant impact on success, but implant length was significantly related to an improved survival rate. Implant lengths of 13 mm or more resulted in significantly enhanced survival rates (93.1%) in comparison to shorter implants (62.1%). In the study of Takahashi et al,24 2 of 19 implants failed, with both being 7 mm long; the other implants in this study ranged from 10 to 18 mm in length. Thus,
the authors suggested that implants placed in grafted alveolar cleft defects should be at least 10 mm long. Matsui et al22 attributed a high survival rate (98.6%) to the use of implants longer than 13 mm in almost all cases. However, in the study of Kramer et al, more than half the patients (24 of 45) received machined-surface implants. There is a significant lack of information regarding esthetic outcomes in cleft patients compared with those achieved with conventional fixed prosthodontics and implant-supported restorations in patients without a history of alveolar clefts.35 Lilja et al30 pointed out that in grafted cleft defect sites, it is more difficult to achieve ideal positioning of the implant, and sometimes a more palatal position had to be used after additional bone grafting; this in turn, can compromise esthetics. Härtel et al found that angled implant positions and less-than-ideal angulation were observed when minimal bone was available.23 The crestal bone height at the site of the implant determines the vertical prosthetic crown length. An analysis of esthetic results, such as buccal mucosal recession or loss of interdental papillae of implants in the alveolar cleft area, was reported in only one study included in this review.26 The study demonstrated papilla shortening or loss and longer definitive crown length compared to the contralateral tooth and conventional implant-supported crowns. However, these esthetic compromises may be hidden in many cases; because more than half of the patients with alveolar clefts had a limited lip elevation, the gingival soft tissues were not displayed when talking or smiling.34 In the present review, no studies evaluated the restorative or biologic results, such as the occurrence of restorative complications or periimplant diseases of dental implants, in alveolar cleft grafting areas.
CONCLUSION Within the limitations of the small number of studies included in the present review, the following statements can be made. 1. One-stage procedures combining bone grafting and implant placement may not be optimal in alveolar cleft defects because of the high complication rates. 2. Four hundred eighty-four dental implants in 377 participants were investigated. Nearly half of the patients required regrafting before implant insertion; intraoral sources including the mandibular symphysis and ramus may provide predictable sources of donor bone when a relatively small volume of bone is required.
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Wang et al
3. The survival rate of dental implants was 91.5% ± 4.77%, indicating that this is a reliable treatment option for alveolar patients in the short term (< 5 years). However, a great deal of variation in marginal bone loss was observed among studies. 4. The esthetic outcomes of implant therapy have not been comprehensively evaluated in patients with a history of alveolar clefts. The limited studies reporting these parameters cited papilla shortening or loss and a longer definitive crown length as esthetic drawbacks. 5. Randomized controlled clinical trials and prospective studies with longer follow-up time and larger samples are necessary to evaluate the criteria for implant survival and success and peri-implant clinical parameters to validate the current findings.
ACKNOWLEDGMENTS This study was funded by the National Natural Science Foundation of China (81070813, 81100788, 31370983, 81371190), Science and Technology Commission of Shanghai Municipality (13ZR1424000), the Combined Engineering and Medical Project of Shanghai Jiao Tong University (YG2012MS32), the Key Project of Chinese Ministry of Education (212080), Grants for Scientific Research of BSKY (XJ201109), and the Young Top-notch Talent Support Scheme from Anhui Medical University. The authors reported no conflicts of interest related to this study.
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