Abstract
Objective
The objective of this study is to retrospectively evaluate the clinical outcomes of alveolar ridge preservation (ARP) in the compromised extraction sockets using autogenous cortical‐lamina anchoring technique (CAT).
Material and methods
Twenty patients were treated with ARP in the compromised extraction sockets by applying CAT. Then implant placement and crown delivery was performed. A planned follow‐up was performed by analyzing various outcome measures to evaluate the clinical outcomes, including primary outcome measures [radiographic assessment of residual alveolar ridge height (RARH) and residual alveolar ridge width (RARW)] and secondary outcome measures [clinical assessment of the healing of the soft and hard tissue, survival rates of implants, marginal bone loss (MBL) evaluation of implants, buccal bone thickness (BBT), and esthetic treatment outcomes].
Results
Among the 20 patients, 17 were consecutively treated and 3 dropped out after implant crown delivery because of loss to follow‐up. After the ARP, the initial RARH (12.37 mm) significantly increased to 19.29 mm (P < .05). No significant difference was detected in the RARW before (7.92 ± 1.18 mm) and after (7.92 ± 1.18 mm) the ARP, but reduce to 6.99 ± 1.18 mm at the implant placement and 6.64 ± 0.77 mm at the 3‐year follow‐up (P < .05). The MBL at the implant crown delivery (0.13 ± 0.12 mm) significantly increased to 0.31 ± 0.14 mm at 1‐year follow‐up and 0.56 ± 0.23 mm at 3‐year follow‐up, respectively. The bone loss was limited (<1 mm) but statistically significant (P < .05). The BBT at the implant placement (2.53 ± 0.56 mm) significantly reduced to 2.23 ± 0.44 mm at implant crown delivery and 2.14 ± 0.40 mm at 3‐year follow‐up, respectively. The bone loss was also limited (<0.5 mm) but statistically significant (P < .05). Each implant site showed acceptable aesthetic outcome and the average score was 16.4. The incisions healed uneventful in all patients and the implant survival rate was 100% during the 3‐year follow‐up.
Conclusion
Autogenous CAT was successfully applied to preserve the height and width of alveolar ridge in the compromised extraction sockets.
Keywords: alveolar ridge preservation, compromised extraction sockets, cortical‐lamina anchoring technique, implant, residual alveolar ridge height, residual alveolar ridge width
What is known
Alveolar ridge preservation has been reported as an evidence‐based approach to manage the compromised extraction sockets.
There are some disadvantages of current reported alveolar ridge preservation techniques in the compromised extraction sockets.
What this study adds
Our cortical‐lamina anchoring technique of alveolar ridge preservation was successfully applied in the compromised extraction sockets.
More clinical trials and further observations are needed to confirm our findings.
1. INTRODUCTION
Tooth extraction leads to dimensional changes in bone architecture and the mucosal tissue will also collapse immediately. 1 Moreover, compromised extraction sockets undergo more pronounced atrophy as a result of the natural remodeling process. 2 , 3 , 4 However, these soft and hard tissue changes in the required dental implant area are most likely to lead to increased difficulty in placing the implant in a suitable position for prosthodontics, especially, it might be a great challenge to achieve acceptable aesthetic outcome. In order to resolve this problem, alveolar ridge preservation (ARP) and augmentation protocols have reported as an evidence‐based approach to manage these compromised extraction sockets. The purpose of ridge preservation techniques is to limit the dimensional changes following tooth extraction at intact sockets, while ridge augmentation techniques are applied to either enlarge the ridge profile or reconstruct bone at deficient extraction sockets beyond the skeletal envelope. 5 Furthermore, the technique of immediate ARP in the compromised extraction sockets can effectively maintain the subgingival contour, reduce the treatment procedure and the patient's financial burden.
Although ARP techniques have been universally used in the past and received a positive outcome, more recent research has focused on a variety of materials and techniques; these techniques are performed to counteract changes in soft tissue and hard tissue that follow tooth extraction. Preservation of hard tissue with a prolonged healing time before implant placement has been suggested when buccal bone plate loss reaches more than 50%. 1 Bone substitute was commonly used to fill the extraction socket during ARP, such as artificial synthetic materials, xenograft, and autogenous or allogenic graft materials, and barrier membrane were used to cover the bone‐grafting materials. 2 For counteracting pressure and muscular activity from soft tissue, it is difficult to maintain contour stability when using absorbable membrane with particulate bone grafts. For avoiding ridge collapse, nonabsorbable such as e‐PTFE (expanded polytetrafluoroethylene) or titanium mesh reinforced e‐PTFE were widely applied; however, membrane exposure is a common complication, and the average exposure rates of 29.3% for e‐PTFE was reported by Thoma et al, once membrane exposure and the ensuing infection will frequently lead to early removal of the membrane. 3 Furthermore, reentry is needed for removing nonabsorbable at the subsequent treatment procedure that may prolong the treatment time. Various materials were used for these procedures, but none of the material or techniques demonstrated were more favorable than others were. 4 Most relevant phenotypic features of the extraction socket could impact the outcome of ARP, such as buccal bone thickness (BBT), integrity, dehiscence, or fenestration. The socket types with intact or dehiscent buccal bone were deeply discussed and different techniques were advised according to the decision tree, especially, nonabsorbable membrane was used for covering dehiscent buccal bone, 5 while the integrity of palatal bone was rarely concerned, and severe bone plate defect of both palatal and buccal was seldom reported for ARP. Bone plate defect of both palatal and buccal was the most common type of extraction socket described as Type IV, accounting for 86.87% of the sockets (258/297), and a two‐wall defect with more than 50% buccal and palatal (or lingual) bone loss and soft tissue in the normal position described as Type IV B, accounting for 39.34%. 6 Space maintenance and bone‐grafting materials stability are both crucial factors for predictable bone regeneration; it is hard to match these requirements for nonabsorbable membrane fixing in those severe bone plate defect cases. In view of the disadvantages of the mentioned methods, the use of cortical laminae grafting for ARP was first performed and evaluated in this study.
Cortical lamina grafting was used to rebuild bone plates like as shells showed in “shell technique.” Khoury demonstrated the graft shell technique, harvesting delicate cortical mandibular shells, which were positioned to bound the resorbed alveolar ridge, constructing a three‐dimensional alveolar graft with large osteogenic capacity and enhanced vascular ability. 7 The advantage is conferred by cortical laminas that act as rigid devices, such as titanium mesh and titanium‐reinforced PTFE, which could directly integrate into the recipient site. In addition, the stable box created with thin bone blocks and the resulting stable biological space filled with autologous bone fragments increases the number of important bone cells in the graft area and enhances the quality of graft revascularization and regeneration. 8 , 9 However, this method has some disadvantages. Fixations of the devices are often used to maintain the initial stability of the thin bone block in shell technique. During the healing period, the application of fixation devices such as nonabsorbable membranes, metal devices, and screws may probably affect the revascularization of the area by locally blocking blood infiltration and blood supply. Subsequently, removal of these nonabsorbable devices requires reentry operations, which will inevitably increase trauma and prolong the treatment period. 10 In order to overcome these disadvantages, we adopted a modified method of ARP by using autogenous cortical‐lamina anchoring technique (CAT) in the compromised extraction sockets. No titanium mesh or titanium screw was involved, and a secondary invasive surgery was avoided during the whole treatment procedure. Therefore, the aims of this present retrospective case series were to clinically evaluate the augmentation of hard tissue height and maintenance of hard tissue width regarding this present technique in the compromised extraction sockets.
2. MATERIALS AND METHODS
2.1. Study population, inclusion/exclusion criteria, instruments, and materials
In this retrospective case series study, the subjects were selected from III‐degree mobility of a single tooth 11 of the maxilla who had been treated with ARP using autogenous bilamina cortical grafting with insert fixation technique between January 2015 and September 2017 in the Center of Oral Implantology, Stomatological Hospital, Southern Medical University. Single tooth of III‐degree mobility with periradicular bone resorption was caused by either endodontic origin or combined periodontic‐endodontic lesions, but excluding accompany with soft tissue recession or bone resorption extending to adjacent teeth. There was no irreversible pulpitis, pulp necrosis, periodontitis, or symptomatic apical periodontitis regarding the conditions of adjacent teeth. All the compromised extraction sockets were classified “Type IV‐B” according to Jung‐Ju Kim, a two‐wall defect with more than 50% buccal and palatal bone loss and soft tissue in the normal position. 6 This study was approved by the Ethics Committee of Stomatological Hospital, Southern Medical University, China (Ethical Permission No. 202007) and was conducted in accordance with the Helsinki Declaration revised in 2013. The recommendations for strengthening the reporting of the observational studies in epidemiology (STROBE) were followed.
The inclusion criteria were as follows: over 18 years of age at the time of surgery; Type IV‐B compromised extraction sockets; a single tooth with III‐degree mobility in the maxilla with vertical defect of alveolar ridge ≥6 mm and ≤ 10 mm; generally healthy and able to follow the required surgical procedures; the periodontal conditions of adjacent teeth were in accordance with the definition of periodontal health described by Lang and Bartold 12 ; patients compliant with regular visits to receive oral prophylaxis.
The exclusion criteria were as follows: systemic diseases and related surgical contraindications; smoking >10 cigarettes per day; pregnancy or lactating status; psychiatric problems; oral infection and uncontrolled periodontal disease.
The following surgical instruments and materials were used: implants (Zimmer Biomet, Warsaw, Indiana, USA), a piezosurgery device (Silfradent, Sofia [FC], Italy), extraction kit (SBP 0750, Silfradent, Sofia [FC], Italy) and osteotomy kit (SBP 0700, Silfradent, Sofia [FC], Italy), and micro cutting wheel (Changsha Tiantian Dental Equipment Co., Ltd. Hunan, China). The bone substitute (deproteinized bovine bone material; Bio‐Oss, Geistlich Pharma AG, Switzerland) and collagen membrane (Bio‐Gide, Geistlich Pharma AG, Switzerland) were used as biomaterials.
2.2. Clinical procedures
2.2.1. Timeline of the clinical procedures
Patients underwent cone beam computed tomography [CBCT, NewTom VGi; NNT software version 9.0, NewTom Inc., Verona, Italy; CBCT parameters: FOV (D × H), 15 cm × 15 cm; voxel size, 0.20 mm; voltage, 110 kV; mAs, 122] during different treatment processes and the data for the radiographic assessment of residual alveolar ridge height (RARH) and residual alveolar ridge width (RARW) were acquired. ARP with CAT was performed using piezosurgery for all cases. Implant placement was performed 3 months after ARP, then implant crown delivery 3 months after the placement. Moreover, a planned follow‐up was performed by analyzing various outcome measures to assess the success of the whole procedure (Figure 1).
FIGURE 1.
Timeline of the clinical procedures
2.2.2. Preoperative procedure
Following enrolment, all patients received oral hygiene instructions until a clinically acceptable oral environment was achieved.
2.2.3. Surgical ARP and implant placement protocol
All patients received antibiotics half an hour preoperatively (0.375 g cefaclor sustained‐release tablets and 1.2 g/L chlorhexidine mouth rinse). All surgical procedures were performed by one experienced surgeon. Local anesthesia was administered preoperatively, the loose tooth was extracted, and the wound was carefully scraped with a curette to remove inflamed tissue.
Surgical incision was performed in the buccal mesial and distal interdental papilla and slightly released buccal mucoperiosteal flap (Figure 2A). To harvest the precise size of the bone graft, the size of the defect of the alveolar ridge was measured for reference. The external oblique ridge or line was usually used as donor site. The graft was cut off via piezosurgery, and the inferior alveolar nerve and roots of the teeth were carefully protected during osteotomy. The block graft was sliced into two pieces for application via piezosurgery or a micro cutting wheel. Two parallel notches with a depth of 3–5 mm were prepared by piezosurgery and narrow bone chisel along the edge of labial and palatal sides of the defect area in the basic bone (Figure 2B). Following this, the lamina grafts were tightly inserted into the notches for bone wall reconstruction (Figure 2C). Next, the new formed gap between the reconstructed bone walls was filled with bone substitutes (deproteinized bovine bone material; Bio‐Oss, Geistlich Pharma AG, Switzerland, 0.5 g or more) (Figure 2D) and further covered by collagen membrane (Figure 2E). Sufficient loosening of the mucosa was performed. If necessary, a trapezoid appended incision was made for relaxation. Finally, buccal flaps were sutured (Figure 2F). After the surgical procedure, all the patients were treated for 5 days with Cefaclor (375 mg two times daily; Shandong, China) and Tinidazole (1000 mg one time daily; Zhejiang, China).
FIGURE 2.
Schematic representation of the ARP surgical protocol. (A) Surgical incision was performed in the buccal mesial and distal interdental papilla and slightly released buccal mucoperiosteal flap. (B) Two parallel notches with a depth of 3 mm are cut by piezosurgery along the edge of labial and palatal sides of the defect area. (C) Two lamina grafts are fixed into the notches tightly for 3‐dimensional bone wall reconstruction. (D) The gap in the reconstructed 3‐dimensional bone walls is filled with bone substitutes. (E) The gap is further covered by the collagen membrane. (F) The buccal flaps are sutured. ARP, alveolar ridge preservation
CBCT was used to evaluate the bone healing status at 3 months after ARP. According to the evaluation outcomes, the implant placement with flapless was performed at 3 months after ARP, and the depths of implant placement in the basal bone were about 3–5 mm to obtain good primary implant stability. All implants were transmucosal healing and inserted between the bilamina cortical graftings and the insertion torque values was more than 10 N/cm (Table 1). Next, the implant received the final crown delivery with cement‐retained restoration.
TABLE 1.
Demographic data of patients and implant‐related characteristics (No. 7, No. 18, and No. 20 dropped out after implant crown delivery and was lost to follow‐up)
| Demographic data of patients | Implant‐related characteristics | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Serial number of patients | Age (years) | Gender | Smoke: yes (1–10/day)/no | Gingiva biotype | Initial vertical defect in buccal aspect (mm) | Initial vertical defect in palatal aspect (mm) | Implants with initial torque (N/cm) | Wound healing (primary/secondary intention) | Implant location (teeth position) | Implant length (cm) |
| No. 1 | 32 | Female | No | Thick | 10.2 | 8.0 | 15 | Secondary | 11 | 11.5 |
| No. 2 | 41 | Male | No | Thick | 8.5 | 5.5 | 30 | Primary | 22 | 11.5 |
| No. 3 | 50 | Male | No | Thick | 9.0 | 7 | 25 | Primary | 13 | 13 |
| No. 4 | 55 | Male | Yes | Thick | 6.5 | 5.5 | 35 | Primary | 11 | 13 |
| No. 5 | 52 | Male | No | Thin | 5.6 | 4.8 | 15 | Secondary | 21 | 11.5 |
| No. 6 | 54 | Male | No | Thick | 8.6 | 5.4 | 30 | Primary | 23 | 13 |
| No. 7 | 38 | Male | No | Thin | 6.7 | 5.5 | 10 | Primary | 22 | 11.5 |
| No. 8 | 23 | Female | No | Thick | 6.0 | 5.0 | 35 | Primary | 11 | 11.5 |
| No. 9 | 32 | Male | No | Thick | 7.0 | 7.4 | 35 | Primary | 11 | 13 |
| No. 10 | 28 | Female | No | Thin | 9.6 | 8.4 | 25 | Secondary | 12 | 11.5 |
| No. 11 | 36 | Male | No | Thick | 8.0 | 6.2 | 20 | Primary | 11 | 11.5 |
| No. 12 | 26 | Male | Yes | Thick | 7.0 | 7.8 | 30 | Primary | 11 | 11.5 |
| No. 13 | 45 | Female | No | Thick | 9.1 | 8.5 | 25 | Primary | 21 | 11.5 |
| No. 14 | 44 | Male | No | Thin | 8.0 | 6.8 | 15 | Secondary | 22 | 11.5 |
| No. 15 | 50 | Male | Yes | Thick | 8.0 | 7.2 | 30 | Primary | 23 | 13 |
| No. 16 | 30 | Female | No | Thin | 6.5 | 7.9 | 20 | Secondary | 12 | 11.5 |
| No. 17 | 26 | Female | No | Thick | 9.2 | 6.8 | 15 | Primary | 21 | 11.5 |
| No. 18 | 23 | Male | No | Thick | 7.5 | 4.5 | 30 | Primary | 21 | 11.5 |
| No. 19 | 34 | Male | Yes | Thin | 7.0 | 7.6 | 25 | Secondary | 22 | 11.5 |
| No. 20 | 61 | Male | No | Thick | 7.5 | 5.9 | 25 | Secondary | 12 | 11.5 |
2.3. Primary outcome measures
2.3.1. Radiographic assessment of RARH and RARW
The technique is proposed for reconstruction of vertical defects (Figure 3A, vertical defects >6 mm). The primary outcome measures were the results of bone augmentation on the RARH and RARW. Data on the RARH and RARW were obtained through CBCT scans preoperatively, postoperatively, at implant placement, implant crown delivery, and during a 3‐year follow‐up after implant crown delivery.
FIGURE 3.
Measurement methods for RARW and RARH. The technique is proposed for reconstruction of vertical defects (vertical bone loss >6 mm). The RARW is measured as the distance between the highest points of the residual alveolar ridge at the labial/palatal aspect (white arrow). The RARH measurements are taken from the highest point of the residual alveolar ridge at the labial/palatal aspect to the nasal base (red arrow). The angle between the RARW and RARH lines is 90° (blue line). RARH is calculated as the mean of RARH values of the labial and palatal aspects (A shows the measurement methods; B is the 3‐dimensional reconstruction of the CBCT scans). RARH, residual alveolar ridge height; RARW, residual alveolar ridge width
The RARW was measured as the distance between the highest points of the residual alveolar ridge at the labial/palatal aspect (Figure 3A, white arrow). The RARH measurements were taken from the highest point of the residual alveolar ridge at the labial/palatal aspect to the nasal base (Figure 3A, red arrow). The angle between the RARW and RARH lines was 90° (Figure 3A, blue line). Furthermore, because the RARH values of the labial and palatal aspects were different, RARH was calculated as the mean of RARH values in labial and palatal aspects. The 3‐dimensional reconstruction of the CBCT scans is used to provide a valuable reference to assess in different time points of the CBCT scans which were in the same sagittal view (Figure 3B).
2.4. Secondary outcome measurements
2.4.1. Clinical assessment of the soft and hard tissue healing
Healing of the soft tissues was clinically assessed and defined as primary intention without any tissue necrosis, infection, suppuration, or wound dehiscence with bone graft exposure. Successful integration of the graft was evaluated by the following criteria: absence of pain, infection, subjective discomfort, or radiographic signs of bone graft resorption, and graft stability at the time of implant placement. 13 Furthermore, the visual analogue scales (VAS) 14 questionnaire is used to evaluate the postoperative pain or discomfort degree at different time points.
2.4.2. Survival rates of implants
The criteria for implant survival include no pain on function; 0 mobility; 2–4 mm radiographic bone loss and no exudates history. 15
2.4.3. Marginal bone loss (MBL) evaluation of implants and BBT change
Among 20 selected implants, a total of 17 implants were included for MBL measurement based on availability of the baseline and latest periapical radiographs. The measurement method was following the conducted by a previous study. 16 The measurements of BBT change are based on the CBCT scans after implant placement, at implant crown delivery, and 3 years after implant crown delivery.
2.4.4. Evaluation of esthetic treatment outcomes by pink esthetic score and white esthetic score (PES/WES) analysis
The PES/WES analysis was performed to evaluate esthetic treatment outcomes when finished the implant crown delivery, and each implant site was scored together, following the order of the 10 PES/WES parameters.
2.5. Statistical analysis
All the measurement data of RARH, RARW, and MBL were statistically analyzed with a repeated measures analysis of variance (one‐way repeated measure ANOVA). Bonferroni correction was conducted for multiple‐comparison correction. The RARH, RARW, and MBL (mm) between various measurement time points were performed by paired t test or Wilcoxon signed‐rank test after using the Shapiro‐Wilk test to test the normality. Multivariate logistic regression analysis was used to estimate the association between gender and RARH (SPSS software, version 20.0, IBM Corporation, Armonk, NY, USA). Data were presented as the mean ± standard deviation. The significance level was defined as α = .05.
3. RESULTS
3.1. Study data
Twenty patients with 20 implant sites met the inclusion criteria after preliminary screening. These patients included 14 males and 6 females with an average age of 39 years (aged 23–61 years). Moreover, no significant difference was detected between male and female (P > .05). Following a 3‐month healing period after ARP, all patients received a total of 20 implants and finished implant crown delivery after an additional 3 months. Among the 20 patients, 17 patients with 17 implants were consecutively treated and 3 dropped out. The dropout rate was 15.0% and the reason was loss to follow‐up after implant crown delivery (Table 1).
The average postoperative VAS score of pain/discomfort was 3.18 ± 0.85 at 3 days after ARP, while was 0.60 ± 1.27 1 week after ARP and no pain/discomfort 2 week after ARP, respectively. Overall, 19 patients experienced mild to moderate pain during the first 3 days after ARP and then the pain was significantly relieved in 1 week after ARP. Sixteen patients were followed up without any obvious pain/discomfort and four patients with very mild pain 1 week after ARP (Table 2).
TABLE 2.
Pain/discomfort VAS units (with 0 = no pain and 10 = unbearable pain)
| Variable | Time points | Mean ± SD | Range | Number of patients |
|---|---|---|---|---|
| Pain/discomfort (VAS score) | 3 days after ARP | 3.18 ± 0.85 | 3–5 | 19 |
| 1 week after ARP | 0.60 ± 1.27 | 0–1 | 4 | |
| 2 weeks after ARP | 0.00 | 0 | 0 |
Abbreviation: VAS, visual analogue scales.
Early wound dehiscence occurred postoperatively in two patients, including one case was slight wound dehiscence within 5 mm and gradually healed in 1 week. Another wound dehiscence with 6 mm also healed after re‐suture by releasing the flap with trapezoid appended incision. Exposed edges of bone grafts at the recipient sites were found in one case with a thin gingival biotype, causing delayed soft tissue healing. The exposed edges were polished with a high‐speed turbine handpiece and all wounds healed uneventful within 1 week. No donor‐site complications occurred. The overall complication rate was 17.6% in 17 patients. Moreover, the survival rates of all 17 implants were 100% at the 3‐year follow‐up.
3.2. Changes in the RARH and RARW at different time points
After the ARP operation, the initial RARH (12.37 ± 1.70 mm) significantly increased to 19.29 ± 2.05 mm. The mean RARH gain was 6.92 mm after ARP (Figure 4A, *P < .05). By 3 months after the ARP, the RARH had declined to 18.69 ± 1.69 mm and slightly absorbed to 18.56 ± 1.70 mm at the time of implant crown delivery (Figure 4A, P > .05). No significant difference was detected in the RARW before (7.92 ± 1.18 mm) and after (7.92 ± 1.18 mm) the ARP, but reduce to 6.99 ± 1.18 mm at the implant placement and 6.64 ± 0.77 mm at the 3‐year follow‐up (Figure 4B, *P < .05). Above all, these data showed a stable clinical outcome.
FIGURE 4.
Changes in RARH and RARW at different time points. After the ARP operation, the initial RARH (12.37 ± 1.70 mm) is significantly increased to 19.29 ± 2.05 mm. The mean RARH gain is 6.92 mm after ARP (A, *P < .05). No significant difference was detected in the RARW before (7.92 ± 1.18 mm) and after (7.92 ± 1.18 mm) the ARP, but reduce to 6.99 ± 1.18 mm at the implant placement and 6.64 ± 0.77 mm at the 3‐year follow‐up (B, *P < .05). ARP, alveolar ridge preservation; RARH, residual alveolar ridge height; RARW, residual alveolar ridge width
3.3. MBL and BBT outcomes
The MBL at the time point of implant crown delivery (0.13 ± 0.12 mm) significantly increased to 0.31 ± 0.14 mm at 1‐year follow‐up and 0.56 ± 0.23 mm at 3‐year follow‐up, respectively. The bone loss was limited (<1 mm) but statistically significant (Figure 5A, *P < .05). The BBT at the implant placement (2.53 ± 0.56 mm) significantly reduced to 2.23 ± 0.44 mm at implant crown delivery and 2.14 ± 0.40 mm at 3‐year follow‐up, respectively. The bone loss was also limited (<0.5 mm) but statistically significant (Figure 5B, *P < .05).
FIGURE 5.
MBL and BBT outcomes. The MBL at the time point of implant crown delivery (0.13 ± 0.12 mm) significantly increased to 0.31 ± 0.14 mm at 1‐year follow‐up and 0.56 ± 0.23 mm at 3‐year follow‐up, respectively. The bone loss was limited (<1 mm) but statistically significant (A, *P < .05). The BBT at the implant placement (2.53 ± 0.56 mm) significantly reduced to 2.23 ± 0.44 mm at implant crown delivery and 2.14 ± 0.40 mm at 3‐year follow‐up, respectively. The bone loss was also limited (<0.5 mm) but statistically significant (B, *P < .05).
3.4. Esthetic treatment outcome
The detailed PES and WES of all 20 included implants were shown in Table 3. Each implant site showed acceptable aesthetic outcome and the average score was 16.4 (Table 3).
TABLE 3.
Detailed PES and WES of all 20 included implants
| PES | WES | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Serial number of patients | Mesial papilla | Distal papilla | Curvature of facial mucosa | Level of facial mucosa | Root convexity, soft tissue color, and texture | Total PES | Tooth form | Tooth volume/outline | Color (hue/value) | Surface texture | Translucency and characterization | Total WES | Total PES + WES |
| No. 1 | 1 | 1 | 2 | 2 | 2 | 8 | 2 | 2 | 2 | 2 | 1 | 9 | 17 |
| No. 2 | 2 | 1 | 2 | 2 | 2 | 9 | 2 | 2 | 2 | 1 | 1 | 9 | 18 |
| No. 3 | 2 | 2 | 2 | 2 | 2 | 10 | 2 | 2 | 1 | 2 | 2 | 9 | 19 |
| No. 4 | 1 | 1 | 2 | 1 | 2 | 7 | 2 | 2 | 1 | 2 | 1 | 8 | 15 |
| No. 5 | 1 | 1 | 2 | 1 | 1 | 6 | 2 | 1 | 2 | 2 | 1 | 8 | 14 |
| No. 6 | 2 | 1 | 2 | 2 | 2 | 9 | 2 | 1 | 2 | 1 | 2 | 8 | 17 |
| No. 7 | 1 | 2 | 2 | 1 | 2 | 8 | 2 | 1 | 2 | 1 | 1 | 7 | 15 |
| No. 8 | 2 | 1 | 2 | 1 | 2 | 8 | 2 | 2 | 2 | 1 | 1 | 8 | 16 |
| No. 9 | 2 | 2 | 1 | 1 | 2 | 8 | 2 | 2 | 2 | 1 | 1 | 8 | 16 |
| No. 10 | 1 | 1 | 2 | 1 | 2 | 7 | 2 | 1 | 2 | 1 | 2 | 8 | 15 |
| No. 11 | 1 | 2 | 1 | 2 | 1 | 7 | 2 | 1 | 1 | 2 | 1 | 7 | 14 |
| No. 12 | 2 | 2 | 2 | 2 | 1 | 9 | 2 | 2 | 2 | 2 | 1 | 9 | 18 |
| No. 13 | 1 | 2 | 2 | 2 | 1 | 8 | 2 | 2 | 1 | 2 | 2 | 8 | 16 |
| No. 14 | 1 | 1 | 2 | 1 | 1 | 6 | 2 | 2 | 2 | 1 | 1 | 8 | 14 |
| No. 15 | 2 | 2 | 1 | 2 | 2 | 9 | 2 | 2 | 2 | 1 | 1 | 8 | 17 |
| No. 16 | 1 | 1 | 2 | 1 | 2 | 7 | 2 | 2 | 2 | 2 | 1 | 9 | 16 |
| No. 17 | 2 | 2 | 1 | 2 | 1 | 8 | 2 | 1 | 2 | 2 | 2 | 9 | 17 |
| No. 18 | 2 | 1 | 2 | 2 | 2 | 9 | 2 | 2 | 2 | 2 | 2 | 10 | 19 |
| No. 19 | 1 | 2 | 2 | 1 | 2 | 8 | 2 | 1 | 2 | 2 | 1 | 8 | 16 |
| No. 20 | 2 | 2 | 2 | 1 | 2 | 9 | 2 | 2 | 2 | 2 | 2 | 10 | 19 |
| Average= | 16.4 | ||||||||||||
4. DISCUSSION
Tooth extraction affects causes homeostatic and structural changes in periodontal tissues, leading to alveolar ridge atrophy. ARP is carried out to avoid ridge resorption after extraction. 17 , 18 Bilamina cortical grafting was optional methods for severe bone defect with buccal and palatal bone plate loss post‐extraction. First, it is suitable for vertical bone augmentation in extraction sockets with moderate to severe bone defects, and is not restricted by the morphology of the defect. Second, it could shorten the treatment period and implant placement should be performed when the cortical laminae integrated with the residual alveolar ridge and become vital. Finally, the flexible application of thin cortical laminae can reduce the amount of bone taken from the donor area, allowing the cortical lamina to have mechanical properties and at the same time reduce the rate of bone resorption.
Thin mandibular cortical bone blocks (laminae) were first used by Khojasteh et al 19 to reconstruct the buccal and palatal (lingual) walls or the occlusal wall of vertical defects. Several techniques based on bone lamina and the detailed information are shown in Table S1. These cortical lamina techniques were described as the “shell technique” in some studies. 20 , 21 A similar technique called bilamina cortical tenting grafting technique was used for reconstruction of vertical and horizontal alveolar ridge defects, where the vertical and horizontal bone gain was 5.70 ± 1.09 and 8.45 ± 0.87 mm, respectively. 22 Another study by Tunkel et al 23 using the shell technique showed excellent results in bone reconstruction, as 3‐dimensional bone regeneration using the shell technique is faster and shows lower resorption rates compared to augmentation procedures with compact cortical bone blocks and GBR. In the present study, the RARH gain was 6.92 ± 0.52 mm, and slight vertical and horizontal resorption was observed after a 3‐month healing period. This is similar to the results of a previous study. 24 Minor resorption rates correspond to a higher gain in bone volume, which may be attributed to the fact that thin bone laminae survive more easily via vascularization. However, these cortical lamina techniques are technique‐sensitive as they require harvesting from the mandibular ramus or chin, extraoral trimming, and fixing the bone laminae on the recipient site with titanium screws. The technical difficulty increases, when the placement or removal of metal devices and screws requires an additional surgical flap elevation with bigger surgical trauma, which would be an injury to the subperiosteal plexus of vessels and causing the obstruction of blood supply to the bone may account for the increased bone resorption compared to the non‐fixation devices, which does not require additional surgical intervention. The results of our present technique can better maintain the stability of bone augmentation and lower bone absorption rate.
In the present study, the bone block was cut into several thin pieces, two of which were usually used as the labial and palatal aspects, with one end of the cortical lamina being fixed by inserting into the notch. In this modified method of bone wall reconstruction for ARP, cortical lamina grafts were initially inserted without fixing any metal devices or rigid barrier membranes, such as a titanium screw or mesh. This technique involves inserting two pieces of cortical laminas into the base bone for more than 3 mm in depth, in order to ensure that the cortical laminas are stable. Moreover, the edges of the laminas are burnished before the cortical embedding so as to protect the soft tissue. Furthermore, we summarized the indication/contraindication and surgical approach of split bone block technique applying to ARP for showing the detailed information (Table S2).
Among the 20 patients, 17 patients with 17 implants were consecutively treated and 3 dropped out. The reason was loss to follow‐up after implant crown delivery. One case is due to personal reasons (moving to a new city) and other two cases refused to accept radiological evaluations further after implant crown delivery. The dropout rate was 15.0% and the high drop‐out rate limits this present study. No donor‐site complications occurred. The overall complication rate was 17.6% in 17 patients. The complications included the wound dehiscence and exposed edges of bone grafts. These complications have been resolved with appropriate treatment.
Based on our results, several advantages were summarized to this technique. First, reentry or larger flaps are not required for removing metal devices in a subsequent procedure. This makes the operation easier and reduces secondary injury to the recipient site, which might cause bone absorption and reduce the suffering of the patient. Second, this modified method—the “cortical lamina inlay technique”—effectively shortens the treatment process; implant placement could be performed 3 months after ARP due to the insert part of the two bone laminae integrated with the residual alveolar ridge within 3 months or even earlier, and crosslinking established when the bone lamina surfaces contact with the periosteum of buccal and palatal mucosa, which was a potentially nourishing source to accelerate bone laminae become vitality. Bone substitutes placed in the gap between the two bone laminae would be removed by implant hole preparing, so, it seems to be unnecessary to wait for more new bone formation in the gaps, the bone laminae integrated well to the base bone is the key factor for further implant osseointegration. Under normal conditions, the implants would be placed among two cortical laminas, so that, even though vibrations are unavoidable, the expanding drills would bore through the gap between bone laminas during the hole preparation without affecting the stability of cortical laminas. Therefore, the lamina grafts could remain steady and maintain vitality, which is beneficial to implant osseointegration. In this study, the implant placement was finished 3 months after the bone wall reconstruction operation, and implant crown delivery could be finished after another 3 months. Third, the two bone laminas sliced from the single block graft were approximately 1 mm thick, and thinner bone laminas are thought to survive more easily. Since the volume of the lamina is smaller, in theory it should need less nutrients from the recipient site for surviving. Furthermore, lamelliform grafts have a larger contact area with the periosteum and marrow cavity, which makes it easier for them to receive nutrients from the wound, which is beneficial for angiogenesis and bone remodeling. Thin bone laminae (1 mm) are thought to allowing for relatively easy vessel penetration, resulting in greater osteogenesis than in the “onlay technique.” These have also been demonstrated to better maintain cell viability, provide higher quantities of osteoblasts and bone morphogenetic proteins, and improve bone regeneration. 25 , 26 Finally, this technique reduces injuries by avoiding the harvesting of more bone blocks from the donor site, and take full advantage of one bone block that can be cut into two. This is more efficient in maintaining osteogenic space and avoid harvesting of more autogenous bone. Less injury may reduce frequent complications in donor sites. Reininger et al 27 reported that the most frequent complications in the mandibular body and ramus donor sites were related to temporary sensory alterations of the mucosa (8.19%) and minor postoperative bleeding (6.55%). 27 In the current study, there were no complications in the bone graft surgery using the mandibular ramus as a donor site in the 17 patients.
The limitation of the study is that the data from this clinical study must be interpreted with caution as this study was not a case‐control study and to date there have been few studies on ARP with this technique in the compromised extraction sockets. Nevertheless, considering that the evaluation of the technique has been mainly assessed in experimental in vivo investigations and in a very limited number of clinical reports, mostly with limited samples, the information reported in this investigation may provide clinicians with useful information on ARP in the compromised extraction sockets of maxillary.
5. CONCLUSIONS
In conclusion, based on the primary and secondary outcome parameters, ARP using autogenous CAT was successfully applied in the compromised extraction sockets of the anterior maxillary zone, although the limitations of this present study. The findings of this study may help to elucidate future beneficial applications of ARP. However, more clinical trials and further observations are needed to confirm these findings.
AUTHOR CONTRIBUTIONS
The concept and design of this study was performed by Zehong Guo and Zhaoqiang Zhang. Data was collected by Zehong Guo, Liqing Yang, and Hong Yang. Data analysis and interpretation of data was performed by Liqing Yang, Yujie Kang, Zhiping Wang, and Fei Ren. Statistics was executed by Xuan Sun and Hong Yang. Funding was secured by Zehong Guo, Zhiping Wang, and Fei Ren. Drafting article was performed by Zehong Guo, Liqing Yang, Hong Yang, and Zhaoqiang Zhang. Critical revision of article was performed by all authors.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
Supporting information
Figure S1. Surgical procedure of ARP using autogenous CAT. (A) The flaps were lifted and the alveolar crest and bone walls were exposed. (B) Two parallel notches each with a depth of 3 mm were prepared by piezosurgery and a narrow bone chisel. (C) The graft is cut off via piezosurgery and then sliced into two pieces. The black rectangular box shows the two bone blocks. (D) The lamina grafts were tightly inserted into the notches. (E) The new formed gap in the reconstructed bone walls were filled with bone substitute. (F) After loosening the mucosa tissue, the wound is sutured
Figure S2. Implant placement and crown delivery procedure. (A) The keratinized mucosa of the wound healed by secondary intention at 3 months after ARP. (B) Keratinized mucosa was removed with a soft‐tissue punch. (C) The implant was placed. The implant with cement‐retained restoration (D), abutment (E), and artificial crown placement (F) was routinely completed. The frontal (G) and occlusal (H) views of the artificial crown were shown at the 3‐year follow‐up
Figure S3. Measurements taken with CBCT scans and intra‐oral radiographs at different time points. Measurements taken preoperatively (A), postoperatively (B and C), 3‐month after ARP (D), after the implant placement (E and F), implant crown delivery (G), and 3‐year follow‐up (H and I)
Figure S4. Histological outcome. The specimens showed a large amount of NBT (A, blue arrow, 20× magnification). NBT presented features of numerous small osteocytes trapping in osteocytic lacunae (A, black arrows; B, black arrows, 20× magnification of A boxed region of interest). Furthermore, osteoblasts were located on NBT surfaces (A and B, red arrows). Many osteoclasts can be observed (C and D, black arrows, 40× magnification). There was abundant medullary space filled with loose connective tissue and many small newly formed vessels (E, black arrows, 40× magnification). In addition, the inflammatory reaction (mainly lymphocytes) was also found (F, black arrows, 40× magnification)
Table S1. Several techniques based on bone lamina and the detailed information
Table S2. The indication/contraindication and surgical approach of split bone block technique applying to ARP
Appendix S1. Supporting information
ACKNOWLEDGMENTS
This work was supported by Key‐Area Research and Development Program of Guangdong Province (No. 2019B010941002); Science research cultivation program of Stomatological Hospital, Southern Medical University (No. PY2020015); Special fund project of science and technology in Guangdong Province (No. 2017B020247009); and Medical Scientific Research Foundation of Guangdong Province, China (C2018076, C2020074). We thank Ms. Xi Zhang for her help to prepare this manuscript. We thank all the patients, doctors, and nurses who participated in the study. We also would like to thank Editage (www.editage.cn) for English language editing.
Guo Z, Yang L, Kang Y, et al. Clinical evaluations of alveolar ridge preservation in compromised extraction sockets with cortical‐lamina anchoring technique: Case series study. Clin Implant Dent Relat Res. 2023;25(1):46‐56. doi: 10.1111/cid.13141
Funding information Key‐Area Research and Development Program of Guangdong Province, Grant/Award Number: 2019B010941002; Science research cultivation program of Stomatological Hospital, Southern Medical University, Grant/Award Number: PY2020015; Special fund project of science and technology in Guangdong Province, Grant/Award Number: 2017B020247009; Medical Scientific Research Foundation of Guangdong Province, China, Grant/Award Numbers: C2020074, C2018076
Contributor Information
Hong Yang, Email: chongzi.luck@qq.com.
Zhaoqiang Zhang, Email: 187234415@qq.com.
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Figure S1. Surgical procedure of ARP using autogenous CAT. (A) The flaps were lifted and the alveolar crest and bone walls were exposed. (B) Two parallel notches each with a depth of 3 mm were prepared by piezosurgery and a narrow bone chisel. (C) The graft is cut off via piezosurgery and then sliced into two pieces. The black rectangular box shows the two bone blocks. (D) The lamina grafts were tightly inserted into the notches. (E) The new formed gap in the reconstructed bone walls were filled with bone substitute. (F) After loosening the mucosa tissue, the wound is sutured
Figure S2. Implant placement and crown delivery procedure. (A) The keratinized mucosa of the wound healed by secondary intention at 3 months after ARP. (B) Keratinized mucosa was removed with a soft‐tissue punch. (C) The implant was placed. The implant with cement‐retained restoration (D), abutment (E), and artificial crown placement (F) was routinely completed. The frontal (G) and occlusal (H) views of the artificial crown were shown at the 3‐year follow‐up
Figure S3. Measurements taken with CBCT scans and intra‐oral radiographs at different time points. Measurements taken preoperatively (A), postoperatively (B and C), 3‐month after ARP (D), after the implant placement (E and F), implant crown delivery (G), and 3‐year follow‐up (H and I)
Figure S4. Histological outcome. The specimens showed a large amount of NBT (A, blue arrow, 20× magnification). NBT presented features of numerous small osteocytes trapping in osteocytic lacunae (A, black arrows; B, black arrows, 20× magnification of A boxed region of interest). Furthermore, osteoblasts were located on NBT surfaces (A and B, red arrows). Many osteoclasts can be observed (C and D, black arrows, 40× magnification). There was abundant medullary space filled with loose connective tissue and many small newly formed vessels (E, black arrows, 40× magnification). In addition, the inflammatory reaction (mainly lymphocytes) was also found (F, black arrows, 40× magnification)
Table S1. Several techniques based on bone lamina and the detailed information
Table S2. The indication/contraindication and surgical approach of split bone block technique applying to ARP
Appendix S1. Supporting information
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.