Radiographic Evaluation of the Alveolar Ridge Splitting Technique

Radiographic Evaluation of the Alveolar Ridge Splitting Technique Combined with Guided Bone Regeneration vs Guided Bone Regeneration Alone in the Anterior Maxilla: A Retrospective Controlled Study

Lulu Zhang, MM1 After tooth extraction, bone loss Yuanding Huang, MD2 in the buccal aspect of the anterior maxilla is more severe, partially because of tissue pressure from the labial side and bundle bone resorp- This study aimed to estimate the radiographic outcomes of the alveolar ridge tion.1 Therefore, the alveolar ridge splitting (ARS) technique combined with guided bone regeneration (GBR) and splitting (ARS) technique with simul- compare its efficacy with GBR alone in maxillary anterior narrow ridges. Forty taneous implantation has been in- patients with 51 implants in the ARS group and 40 patients with 49 implants in troduced to repair bone defects and the GBR group were included. The buccal bone thickness (BBT) at 0 to 4 mm 2 from the implant shoulder immediately and 6 months postoperative were facilitate implant installation. analyzed using cone beam computed tomography. The BBT at both time This method favors cases with points had no statistical disparities between the two groups (P > .05). However, an alveolar crest width of 3 to 5 mm, BBT changes indicated significant disparities, with more BBT preservation particularly in the maxilla, with thin- in the ARS group (P < .05). Compared with GBR alone, the ARS technique ner cortical bone and lower bone combined with GBR, despite obvious buccal bone diminution, could be a density.3 Nevertheless, due to surgi- reliable modality for treating ridge width deficiency in the anterior maxilla. Int J Periodontics Restorative Dent 2020 (9 pages). doi: 10.11607/prd.4512 cal trauma or inadequate blood sup- ply, buccal bone resorption could happen. Hitherto, prior investigations on the ARS procedure mostly dealt with the ridge width alteration and marginal bone loss after surgery4–6 but scarcely reported dimensional changes of the buccal bone during postoperative bone remodeling. Apart from that, the impact of orofacial implant angulation on the coronal buccal bone changes has sparsely been analyzed.7 Recently, however, 1Department of Oral Implantology, Stomatological Hospital of Chongqing Medical University, Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, the popularity of cone beam com- Chongqing, China. puted tomography (CBCT) makes it 2Department of Oral Implantology, Stomatological Hospital of Chongqing Medical possible to observe the buccolingual University, Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of bone configuration. To date, new Higher Education, Chongqing, China. insights advocate the application of Correspondence to: Dr Yuanding Huang, Department of Oral Implantology, patient-reported outcome measures Stomatological Hospital of Chongqing Medical University, No 5, (PROMs) to reflect patients’ feelings Shangqingsi Road, Yuzhong District, Chongqing 400010, China. 8,9 Fax: (+86)-023-88830222. Email: [email protected] about their oral health condition. However, PROMs on the ARS tech- Submitted June 20, 2019; accepted August 25, 2019. ©2020 by Quintessence Publishing Co Inc. nique are still sparse.

doi: 10.11607/prd.4512

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Consequently, this retrospec- Surgical Procedure Postoperative Management tive study aimed to estimate the and Follow-up radiographic and patient-centered With local infiltration anesthesia, a outcomes of the ARS technique crestal horizontal incision and two Patients were instructed to take combined with guided bone re- vertical releasing incisions were amoxicillin and metronidazole and to generation (GBR) and compare its formed, followed by a mucoperios- rinse with 0.2% chlorhexidine mouth- efficacy with GBR alone in maxillary teal flap (Fig 1a). No bone cuts were wash thrice daily for 3 to 5 days. Su- anterior narrow ridges. performed in the GBR group. In the tures were removed after 10 days. ARS group, the alveolar crest was After 6 months of submerged cut horizontally using a piezoelectric healing without any interim pros- Materials and Methods device (Piezosurgery insert #OT7S-3, theses, implant sites were exposed Mectron), 1.5 mm away from the ad- again and healing abutments were Patient Selection jacent teeth or implants, reaching a inserted. Cement-retained provi- 7-mm depth. Two vertical cuts were sional crowns or partial dentures In accordance with the Declaration then performed lateral to the previ- were fabricated to optimize facial of Helsinki, this retrospective con- ous formed groove until reaching soft tissue level and contour for 1 trolled study was implemented in the sufficient depth for the desired im- to 2 months (Fig 1h). Whereafter, Department of Oral Implantology, plant length (Fig 1b). Subsequently, cement-retained definitive super- Stomatological Hospital of Chong the corresponding bone expander structures were placed and patients qing Medical University. The files of (expanding osteotome, Osstem) was were informed of annual follow-up patients who had received the max- inserted into the prepared site, slowly visits (Fig 1i). illary anterior implantation by ARS increasing the intercortical space un- technique with GBR (ARS group) or til enough width was achieved for the by GBR alone (GBR group) from June desired implant diameter (Fig 1c). CBCT Measurements 2014 to June 2017 were screened. All The implant sites were prepared patients signed the informed consent under the manufacturer’s guidelines, The preoperative (T0), immediately about the details and risks of the pro- and the corresponding implants postoperative (T1), and 6 months cedure. The inclusion criteria were were installed nearly 0.5 mm sub- postoperative (T2) CBCT scans were as follows: Having (1) crown insertion crestally in both groups (Fig 1d). Af- made (Fig 2) using the same CBCT for at least 12 months; (2) preopera- terwards, in the ARS group, the gap machine (iCAT, KaVo; field of view: tive, immediately postoperative, and around implants and the surface of 100 × 100 mm; voxel size: 0.4 mm), 6-months–postoperative CBCT data; the expanded bone were filled with and the data were imported into (3) ridge width from 2.5 to 6.5 mm the polymerization of the injectable an image viewing software (Scan and ridge height more than 10 mm; platelet-rich fibrin (i-PRF)10 and depro- eXam Vision, KaVo). The examiner (4) no obvious undercut in the facial teinized bovine bone mineral (DBBM) (L.Z.) measured all variables twice bone; (5) natural teeth or prostheses (Bio-Oss, Geistlich) (Figs 1e and 1f), with an interval of 1 week between in the mandible; and (6) good gen- while the fenestrations and dehis- measurements. The implant served eral health before surgery. The exclu- cences in the GBR group were only as a reference by showing its cen- sion criteria were as follows: (1) ridge filled with DBBM. The graft materi- ter on sagittal views. The natural width ≤ 2.5 mm; (2) having vertical als were then covered by a trimmed teeth or prostheses in the mandible defects in need of vertical bone aug- absorbable barrier membrane (Bio- could also indicate the same loca- mentation; (3) heavy smokers (> 20 Gide, Geistlich), which was stabilized tion on CBCT images. The variables cigarettes/day); and (4) uncontrolled with horizontal mattress sutures. Fi- assessed were as follows (Fig 3): periodontal diseases or systematic nally, the flap was repositioned and (1) ridge width (RW): the distance diseases. sutured without tension (Fig 1g). between the buccal and palatal

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a b c

d e f

g h i Fig 1 The surgical procedure and final restoration in the ARS group. (a) A crestal horizontal incision and two vertical releasing incisions were made to form a mucoperiosteal flap. (b) One horizontal and two vertical bone cuts were formed by the piezoelectric device. (c) The bone expander was inserted to separate the buccal bone plate. (d) The implant was placed subcrestally. (e) The i-PRF (left) and its poly merization with bone grafts (right). (f) Gaps around the implant and the surface of the expanded bone were filled with the bone grafts, covered by a barrier membrane. (g) Sutured operative site. (h) A provisional crown was fabricated. (i) Buccal view of the final restoration.

border of the bone at the crest; coefficient (ICC) was applied to test visual analog scales (VAS) to quan- (2) buccal bone thickness (BBT): the intraexaminer reliability. tify the esthetics and function of distance from the implant surface implant-supported restorations and to the outer margin of bone sub- overall patient satisfaction. Patients stitutes at 0 to 4 mm from the im- Patient-Reported Outcome were instructed to indicate their feel- plant shoulder; and (3) buccolingual Measures ings about each statement by mak- implant angulation7: the angle be- ing a mark on a 10-cm line, labeled tween the implant’s long axis and All included patients were contacted with the worst experience on the left the palatal plane (connection of the by telephone calls to complete a and the best experience on the right. anterior and posterior nasal spine) questionnaire, which was returned The clinician measured the distance in the immediately postoperative by a self-addressed stamped enve- from the beginning of the line to the CBCT view. Based on five samples lope. All eight statements11 in this marking, and this distance was used in each group, intraclass correlation subjective questionnaire utilized as the VAS score for each statement.

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a b c Fig 2 (a) Preoperatively, (b) immediately postoperative, and (c) 6 months postoperative CBCT views.

Results Implant’s long axis

Palatal plane Study Population Implant angulation A total of 80 patients (42 men and 38 women) with 100 placed implants fulfilled the inclusion criteria. The patients’ average age was 38.95 ± 15.82 years (range: 18 to 85 years). 4 mm 3 mm No complications occurred during 2 mm the surgery, and all patients had un- 1 mm eventful healing. All implants were 0 mm in place without any mobility at study termination (December 2018), and the average function time from RW prosthesis delivery to termination Fig 3 CBCT measurements: ridge width (RW) at the crest; buccal bone thickness at 0 to was 21.86 ± 6.03 months (range: 12 4 mm from the implant shoulder; buccolingual implant angulation between implant’s long to 47 months). Forty patients with axis and the palatal plane. 51 implants belonged to the ARS group, and 40 patients with 49 im- Statistical Analysis normally distributed. Consequently, plants belonged to the GBR group.

the differences in BBT at T1 and T2 Patient and implant/prosthetic pa- All statistical analyses were pro- within each group were compared rameters are detailed in Table 1. cessed on SPSS version 22.0 (IBM). by Wilcoxon signed-rank test, where- Descriptive analyses were conduct- as the differences of BBT and VAS ed and presented as means ± stan- scores between the two groups were CBCT Measurements dard deviations for all continuous analyzed with Mann-Whitney U test. variables. Changes in BBT (ΔBBT) at Spearman correlation test detected The ICC on CBCT measurements

0- to 4-mm levels between T1 and T2 the possible association between was 0.89, with good intraexaminer were calculated by subtracting BBT patients’ age, gender, initial ridge reliability. The mean RW in the ARS at T2 from BBT at T1. width, implant angulation, and ΔBBT group was distinctly increased to Shapiro-Wilk test showed that at 0- to 4-mm levels. P < .05 was con- 6.95 ± 1.14 mm immediately after sur- not all continuous variables were sidered statistically significant. gery, and the mean RW in the GBR

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group was 7.75 ± 1.20 mm with sta- Table 1 Patient and Implant Characteristics tistical disparity over the ARS group (P = .004). Six months later, the mean Group RW values were markedly decreased Parameter ARS GBR Total to 5.51 ± 1.07 mm (ARS group) and Patients, n 40 40 80 5.91 ± 1.05 mm (GBR group) with- Gender out statistical disparity between the Male 21 21 42 Female 19 19 38 groups (P = .144). Age, y As exhibited in Table 2, obvi- Mean ± SD 41.53 ± 17.57 36.38 ± 13.60 38.95 ± 15.82 ous buccal contour diminution hap- Range 18 to 85 19 to 65 18 to 85 pened within each group after 6 Initial ridge width, mm months of healing (P < .001). The Mean ± SD 3.97 ± 0.68 3.87 ± 0.75 3.92 ± 0.71 intergroup comparisons at two time Range 2.53 to 5.80 2.85 to 6.11 2.53 to 6.11 points showed that the mean values Implants, n 51 49 100 of BBT at 0- to 4-mm levels had no Implant system statistical disparities in both groups Osstem 33 28 61 Straumann 1 5 6 (P > .05), except for BBT at the Dentis 8 2 10

4-mm level in T2 (P = .007). Interest- Anthogyr 5 3 8 ingly, when considering ΔBBT from NobelActive 4 11 15 T to T , intergroup comparisons re- Implant diameter, n 1 2 3.3–3.7 mm 47 41 88 vealed statistical disparities in favor 4.0–4.5 mm 4 8 12 of the ARS group (P < .05) (Table 3). Implant length , n Spearman correlation test showed 10–12 mm 45 28 73 no correlations between patients’ 13–14 mm 6 21 27 age, gender, initial ridge width, Implant insertion site, n and the ΔBBT at 0- to 4-mm levels Central incisor 32 36 68 Lateral incisor 15 10 25 (P > .05). The mean buccolingual im- Canine 4 3 7 plant angulations in the two groups Prosthesis were 120.2 ± 8.0 degrees (range: Single crown 28 33 61 99.0 to 136.0 degrees) and 118.4 ± Partial denture 3 0 3 8.2 degrees (range: 99.0 to 143.0 Combination crown 9 7 16 degrees). No correlations between Function time, mo Mean ± SD 20.14 ± 6.74 23.65 ± 4.59 21.86 ± 6.03 implant angulation and ΔBBT at Range 12 to 47 15 to 43 12 to 47 0- to 4-mm levels were recognizable ARS group = alveolar ridge splitting plus guided bone regeneration; GBR group = guided in either group (P > .05). bone regeneration only; SD = standard deviation.

PROMs VAS values in Fig 4, most patients soft tissue bleeding around the im- were satisfied with their chewing plant was slightly more than around Of all 80 patients, 61 returned the ability, phonetic ability, and esthetic the natural teeth. Further, patients completed questionnaire, while results. Similarly, most patients would felt that the implant therapy out- 7 (ARS/GBR group: 3/4) were not choose implant therapy again and come was of slightly less worth than reachable and 12 patients (ARS/GBR: would recommend this treatment to the cost. Patients in both groups 3/9) refused to participate because others. However, the implant clean- had similar ratings with no statistical they had moved away. Based on the ness score was relatively low, and the intergroup disparities (P > .05).

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Table 2 BBT (in mm) at 0 to 4 mm from the Implant Shoulder at this study, the BBT at 0- to 4-mm levels in the ARS group at both time T1 and T2 points were comparable to those in Group the GBR group, with slightly higher ARS GBR values at T . Interestingly, in terms BBT Mean ± SD Range Mean ± SD Range P 2 of BBT alteration, the significant 0 mm intergroup differences exhibited T1 2.26 ± 1.01 0.00 to 4.88 2.54 ± 1.04 0.56 to 4.88 .305 T2 1.17 ± 0.83 0.00 to 3.12 1.06 ± 0.93 0.00 to 3.96 .414 quite less buccal bone loss in the P < .001b < .001b ARS group when compared with the 1 mm GBR group. T1 2.76 ± 1.03 0.57 to 6.25 2.90 ± 0.97 0.89 to 5.12 .503 T2 1.64 ± 0.98 0.00 to 3.69 1.42 ± 1.07 0.00 to 4.53 .255 As documented in the litera- P < .001b < .001b ture, GBR has been extensively ap- 2 mm plied to reestablish ridge deficiency. T 3.16 ± 0.98 1.13 to 5.69 3.22 ± 0.97 1.35 to 5.38 .970 1 However, due to poor mechanical T2 2.16 ± 1.04 0.00 to 3.96 1.85 ± 1.02 0.00 to 4.53 .108 P < .001b < .001b properties of absorbable mem- 3 mm branes and grafting materials, this T 3.47 ± 1.01 1.44 to 6.00 3.49 ± 0.95 1.26 to 5.69 .986 1 approach could not effectively resist T2 2.55 ± 1.02 0.00 to 4.56 2.18 ± 0.99 0.00 to 4.82 .056 P < .001b < .001b compression forces from the buccal 4 mm soft tissue, which may lead to mem-

T1 3.81 ± 1.12 1.44 to 6.25 3.55 ± 0.95 1.44 to 5.95 .258 brane collapse and dislocation of T 3.03 ± 0.95 0.00 to 5.95 2.44 ± 1.00 0.00 to 4.53 .007a 2 bone substitutes, thereby causing P < .001b < .001b the existence of fibrous connective BBT = buccal bone thickness; T1 = immediately postoperative; T2 = 6 months postoperative; ARS group = alveolar ridge splitting plus guided bone regeneration; tissue12 and compromising bone GBR group = guided bone regeneration only; SD = standard deviation. 13 aStatistically significant difference between groups (Mann-Whitney U test). formation. In contrast to GBR, bStatistically significant difference between T and T (Wilcoxon signed-rank test). 1 2 the expanded buccal bone by ARS technique could keep particulate Table 3 Changes in BBT (in mm) at 0 to 4 mm from the bone substitutes from dispersing Implant Shoulder and provide architectural support Group by mechanically counteracting the 1,14 ARS GBR buccal mucosal tension. In ad- ∆BBT Mean ± SD Range Mean ± SD Range P dition, the expanded buccal bone 0 mm 1.09 ± 0.89 –0.87 to 3.12 1.48 ± 0.97 0.18 to 4.66 .047* contains osteogenic stem cells and 1 mm 1.12 ± 0.96 –0.90 to 4.25 1.48 ± 1.07 –0.31 to 5.01 .094 growth factors, which could expe- 2 mm 1.00 ± 1.01 –0.66 to 3.43 1.37 ± 0.91 0.00 to 3.69 .032* dite soft tissue healing and bone formation.14 3 mm 0.93 ± 1.06 –0.71 to 3.77 1.31 ± 0.83 –0.10 to 3.52 .009* A previous study showed that if 4 mm 0.78 ± 1.02 –1.09 to 3.77 1.11 ± 0.85 –0.05 to 3.69 .031* an implant was placed with more of BBT = buccal bone thickness; ΔBBT = changes in BBT; ARS group = alveolar ridge splitting plus guided bone regeneration; GBR group = guided bone regeneration only; a palatal tilt, better marginal bone SD = standard deviation. levels could be maintained.15 Thus, *Statistically significant difference between groups (Mann-Whitney U test). the present authors postulated that larger buccolingual implant angula- Discussion port buccal bone volumes regarding tion would cause more buccal bone the ridge splitting procedure, there- loss, especially in the coronal region, To the best of the authors’ knowl- fore making historical comparisons which had more tissue pressure from edge, this study was the first to re- almost impossible. As presented in the labial side.3 However, the buc-

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ARS group (n = 34) GBR group (n = 27)

I can chew well on my implant-supported crowns. 8.93 9.10

I can speak well with my implant-supported crowns. 9.50 9.29

I am satisfied with the esthetic outcome. 9.43 9.20

I can clean my implants very well. 8.46 8.66

8.42 The tissues around implants seldom bleed. 8.59

8.49 I would consider this treatment again, if needed. 8.58

9.16 I would recommend this treatment to others. 9.36

8.25 I think this treatment was worth the cost. 8.17

Fig 4 Mean VAS scores in both groups.

cal bone at 0- to 4-mm levels had subcrestally, which could reduce The gray values were reduced21 and similar diminution in this study, which marginal bone loss.19 However, for inherent artifacts were always pre- resulted in no correlations between ethical reasons, this study only rep- sented around titanium implants,22 buccolingual implant angulation and resented a short-term snapshot of which rendered identification of buccal bone resorption. Of note was buccal bone and failed to assess the bone-implant interface a little that the i-PRF used in the ARS group, marginal bone loss, which could hard. Additionally, the thinner bone a new type of platelet concen- happen after functional loading, around the implant, the more diffi- trates, has been proven to improve especially in the first 6 months post- cult it is to detect the actual bone microvascularization and tissue loading.20 Worthy of note is that the condition.23 It was noted that all the regeneration.16 Furthermore, the ag- BBT at 0- to 4-mm levels were near- results were measured by only one glutination of the i-PRF and graft ma- ly 0 mm at T2 in four patients (ARS/ examiner (L.Z.). Therefore, further terials could facilitate manipulation GBR groups: 1/3 patients). However, studies should include more exam- of bone grafts. The piezoelectric de- there was no implant mobility, no iners and explore a more standard- vice used in the ARS group has also peri-implant infection, and no per- ized method to evaluate BBT. reported more precise bone cuts17 sistent pain in these patients. The Currently, the imperative issue and less tissue damage.18 reason could be insufficient preci- has focused on whether to strip In this study, the internal con- sion when using CBCT to evaluate the periosteum off the buccal bone nection implants were placed the bone volume around implants. surface. Some studies proposed

doi: 10.11607/prd.4512

partial-thickness flap elevation be- Acknowledgments 9. Cosyn J, Thoma DS, Hämmerle CH, De cause the periosteum would im- Bruyn H. Esthetic assessments in implant dentistry: Objective and subjec- 24,25 prove the neovascularization and This study was supported by the National tive criteria for clinicians and patients. prevent any cracked segment from Natural Science Foundation of China (Grant Periodontol 2000 2017;73:193–202. 10. Mourão CF, Valiense H, Melo ER, displacement.26 Nevertheless, a re- No. 31100690) and the Program for Innova- tion Team Building at Institutions of Higher Mourão NB, Maia MD. Obtention of cent systematic review has displayed injectable platelets rich-fibrin (i-PRF) Education in Chongqing in 2016. The au- no statistical disparity in implant sur- and its polymerization with bone graft: thors report no conflicts of interest related Technical note. Rev Col Bras Cir 2015; vival rate between partial-thickness to this study. 42:421–423. and full-thickness flaps.27 In addition, 11. Tey VHS, Phillips R, Tan K. Patient- related outcome measures with implant a retrospective study demonstrated therapy after 5 years. Clin Oral Implants that the ridge expansion through References Res 2017;28:683–688. a partial-thickness or full-thickness 12. Strietzel FP, Khongkhunthian P, Khattiya R, Patchanee P, Reichart PA. Healing flap concomitant with GBR had a . 1 Jiang X, Zhang Y, Chen B, Lin Y. Pressure pattern of bone defects covered by dif- similar cumulative implant success bearing device affects extraction socket ferent membrane types--a histologic remodeling of maxillary anterior tooth. study in the porcine mandible. J Biomed rate and marginal bone loss over A prospective clinical trial. Clin Implant Mater Res B Appl Biomater 2006; 8 years of follow-up.6 Similarly, an Dent Relat Res 2017;19:296–305. 78:35–46. 2. 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