Immediate Single Tooth Replacement With Subepithelial Connective Tissue Graft Using Platform Switching Implants: A Case Series

The success of single immediate tooth replacement in the esthetic zone begins with proper 3-dimensional implant placement along with a properly contoured provisional restoration.1–5 The concept of immediate implant placement and provisionalization (IIPP) was introduced by Wöhrle, and has since been proven to be a predictable treatment modality in ideal esthetic situations, with success rates comparable to those of delayed implant placement with delayed prosthetic loading procedures.6–9 

While IIPP has been shown to be a successful procedure, slight facial gingival recession has been reported following the first year of function.10–14 Facial gingival biotype conversion through subepithelial connective tissue graft (SCTG) procedure at the time of implant placement has been advocated and proven to be successful in preserving soft tissue levels by rendering the gingival tissue more resistant to recession.1,10,15,16 

Peri-implant marginal bone level (MBL) change is one of the parameters used in evaluating implant success rate.17 Recently, it has been suggested that the peri-implant MBL may be influenced by the way the implant and the abutment connect, and that the size discrepancy between the implant and the abutment used, also known as “platform switching,” may be beneficial in maintaining the peri-implant MBL.18 

The purpose of this study was to evaluate the success rate and peri-implant tissue response of platform switching implants following immediate tooth replacement in conjunction with subepithelial connective tissue graft.

This study was approved by the Institutional Review Board of Loma Linda University and was conducted in the Center for Implant Dentistry, Loma Linda University School of Dentistry, California. To be included in this study, the patient must have: (1) been at least 18 years of age or older with good hygiene, (2) had a single failing maxillary (number 4–13) or mandibular (number 20–29) tooth with the presence of adjacent and opposing natural dentition and without active infection, and (3) had sufficient bone volume to accommodate placement of a single implant with a minimum dimension of 3.25 mm × 15 mm. The following patients were excluded: (1) patients with a history of smoking,19 head and neck radiation treatment,20–22 bruxism,23 and parafunction; (2) patients with a lack of stable posterior occlusion; and (3) patients in whom primary implant stability could not be achieved.

All patients received standardized diagnosis and treatment planning (Figures 1 and 2). An acrylic resin provisional shell was fabricated prior to the implant surgery using an autopolymerizing acrylic resin (Jet, Lang Dental, Wheeling, Ill). Following the administration of local anesthetic, the failing tooth was removed atraumatically and an implant (Osseotite Prevail, Biomet 3i, Warsaw, Ind) was placed immediately into the extraction socket with the implant-prosthetic platform 3 mm apical to the predetermined gingival margin (Figure 3).7 Primary implant stability was achieved with a minimum insertion torque of 30 Ncm (manufacturer recommended value, Biomet 3i). Xenograft (Bio-Oss, Osteohealth Co, Shirley, NY) was utilized to fill the implant-socket gap. A customized temporary titanium cylinder (Temporary Cylinder, Biomet 3i) was then placed and hand-tightened onto the implant. Flowable composite resin (PermaFlo, Ultradent Products Inc, South Jordan, Utah) was expressed into the site and photopolymerized to recreate the emergence profile of the extracted tooth. The prefabricated provisional shell was relined with acrylic resin (Jet, Lang Dental) and adapted to the custom temporary abutment. The provisional restoration was adjusted to clear all contacts in centric and eccentric movements, polished, and cemented with non-eugenol temporary cement (TempBond, Kerr Corp, Orange, Calif). A periapical radiograph was taken to ascertain the fit of the provisional restoration and complete cement removal (Figure 4).

An SCTG was harvested from the palate utilizing a single incision technique.24 A full-thickness envelope was created between the labial bony plate and the gingiva of the extraction site.1 The SCTG was inserted into the prepared envelope space and secured using a resorbable suture material (6-0 chromic gut blue, Ethicon Johnson & Johnson, Somerville, NJ) (Figure 5). Light pressure was applied over the SCTG with moist gauze for 10 minutes to minimize blood clot and dead space formation between the graft and the underlying bone.1 

Antibiotics and analgesics were prescribed for postoperative use. Patients were instructed to rinse with 0.12% chlorhexidine gluconate solution (Peridex, Zila Pharmaceuticals Inc, Phoenix, Ariz), refrain from functioning at the surgical site, and remain on a liquid diet for 2 weeks following the surgery. Over the next 3 months, a soft diet was recommended.

At 6 months, the final implant impression was made with poly (vinyl siloxane) impression material (Aquasil Monophase, Dentsply, York, Pa). The final restoration was fabricated as a 1-piece screw retained or a 2-piece cement-retained metal ceramic restoration. The screw-retained restoration was cast in a high noble metal (W3 Ceramic Alloy, Ivoclar Vivadent Inc, Amherst, NY) onto the cast gold abutment (UCLA Abutment, Biomet 3i) followed by ceramic application (Vita Omega 900, Vident Inc, Brea, Calif). The prosthetic screw for the final 1-piece metal ceramic restoration was torqued to 20 Ncm (manufacturer's recommendation, Biomet 3i). The cement-retained restoration consisted of a definitive custom abutment cast in Type IV gold (Monogram IV, Leach & Dillion, San Diego, Calif) onto the cast gold abutment (UCLA Abutment, Biomet 3i) and a definitive metal-ceramic restoration (W-3, Vita Omega 900). The custom abutment was torqued to 20 Ncm (manufacturer's recommendation) and the definitive metal-ceramic restoration was cemented using resin-modified glass ionomer cement (Rely-X, 3M ESPE, St Paul, Minn) (Figures 6 through 8).

All examinations and corresponding data collection were performed by 1 examiner (S.C.). The data, when indicated, was collected and compared between each follow-up time interval: presurgery (T0), immediately after immediate tooth replacement and SCTG (T1), and 3 months (T2), 6 months (T3), and 12 months (T4) after surgery. The implant success/failure and marginal bone level changes were evaluated at T1, T2, T3, and T4; facial gingival level change at T0, T2, T3, and T4; Periotest values at T1 and T3; modified plaque index at T2, T3, and T4; and papilla index at T1, T2, T3, and T4.

The implants were evaluated according to the criteria proposed by Smith and Zarb17 where applicable. The implants were considered a failure with the presence of mobility, peri-implant radiolucency, persistent pain, discomfort, and/or infection.

MBLs on the mesial and distal aspects of each implant were measured with the use of sequential periapical radiographs and long cone paralleling technique with a commercial Rinn XCP holder (XCP post bite blocks 54-0862, Dentsply, Elgin, Ill).25 An occlusal jig constructed with poly (vinyl siloxane) interocclusal record material (Exabite II, GC America, Alsip, Ill) was used to standardize the position and angulation of the film to the X-ray beam. The platform of the implant was used as the reference line (RL) (Figure 9). The distance between the reference line and the implant-bone contact was measured. A value of zero was given when the marginal bone level was at or coronal to the reference line. A negative value was given when marginal bone level was apical to the reference line. The overall MBL of each implant was the average value of mesial and distal measurements. The overall MBL values were compared between each follow-up time interval (T1, T2, T3, and T4), and the MBL change was calculated. The intraexaminer reliability of the measurements was determined by using double assessments of MBL measured 3 months apart by 1 examiner and expressed as the intraclass correlation coefficient (ICC).

A master cast was made at different time intervals (T0, T2, T3, and T4) to evaluate the facial gingival level (FGL). A customized stent fabricated from the preoperative master cast was used to standardize probing points and the direction of probe insertion. Baseplate wax (Type II Dentsply) was placed around the failing tooth, and the modified cast was duplicated. A vacuum-formed, 0.060-inch thick polyethylene terephthalate, glycol modified clear template (Ultradent) was adapted and trimmed to remove all undercuts. This allowed for sufficient clearance to accommodate changes in the contours of the restoration from the provisional to the definitive implant restoration. A perpendicular slot was created at the most apical part of the midfacial gingival level, and the apical border of the customized stent was used as a reference line. The FGL was evaluated at each time interval using a periodontal probe (15 UNC Color-Coded Probe, Hu-Friedy, Chicago, Ill), and the FGL change was calculated. All measurements were made to the nearest 0.5 mm. The intraexaminer reliability of the measurements was determined by using a double assessment of FGL measured 3 months apart by 1 examiner and expressed as the ICC.

The Periotest (Siemens AG, Bensheim, Germany) instrument was utilized to evaluate implant stability at T1 and at T3.26–29 A 6-mm healing abutment (Biomet 3i) was hand tightened onto the implant and utilized as the tapping surface for the Periotest (Siemens) instrument. Measurements were made 2 to 4 times, until 2 duplicate Periotest values (PTV) were registered and recorded.

The presence of plaque was assessed at the mesiolabial, labial, distolabial, mesiolingual, lingual, and distolingual surfaces of the implant provisional and definitive restoration according to the modified plaque index (mPI).30 Only the highest index score of each implant was used for statistical analysis.

The interproximal soft tissue was evaluated using the papilla index score (PIS).31 Mesial and distal PIS values were individually analyzed.

Surgical complications were documented as connective tissue graft necrosis, infection around the implant, and/or any deviation from the manufacturer's placement protocol, which resulted in additional modifications to the surgical site in order to establish adequate primary stability.

Prosthetic complications were documented as any repairs or modifications of the provisional restoration or definitive prosthesis. These included, but were not limited to, debonding of the provisional restoration, fracture of the provisional restoration, occlusal adjustments, and/or abutment screw loosening.

The Friedman test was used to evaluate MBL, FGL, mPI, and PIS; and Wilcoxon signed-ranks test was used to evaluate PTV. The level of significance was set at α  =  .05.

A total of 6 male and 4 female patients between the ages of 22.7 and 67.1 (mean  =  52.1) years participated in this study. Of the 10 implants, 3 were located in the maxillary central incisor, 3 in the maxillary lateral incisor, 2 in the maxillary canine, 1 in the maxillary second premolar, and 1 in the mandibular second premolar position. The implants used were 3.25 × 15 mm (4), 4.0 × 15 mm (4), 5.0 × 13 mm (1), and 5.0 × 15 mm (1).

One patient experienced an early implant failure (number 9) at the 3-month follow-up appointment (T2) due to mobility. Since the implant failure occurred at T2, it was excluded from the data analysis. The remaining 9 implants were stable and maintained osseointegration at the 1-year follow-up (T4), resulting in an overall cumulative implant success rate of 90% (9/10).

The ICC for MBL measurements was 0.955, indicating that the measurement method was reliable and reproducible. Statistical values for the MBL are presented in Table 1. The mean MBL change from T1 to T4 was −0.31 mm. No statistically significant differences (P  =  .10) for MBL were noted between all time intervals.

The ICC for FGL measurements was 0.998, indicating that the measurement method was reliable and reproducible. Statistical values for the FGL are presented in Table 2. The mean FGL change from T1 to T4 was −0.05 mm. No statistically significant differences (P  =  .75) for FGL were noted between all time intervals.

The mean PTV at T3 (−2.0 ± 0.9) was statistically significantly lower than that at T1 (−0.1 ± 2.2) (P  =  .008).

The mPI scores of 0 and 1 were consistently recorded throughout the study (Table 3). There was no statistically significant difference in the mPI (P  =  .56) scores among the 3 time intervals (T2, T3, and T4).

The PIS ranged from 0 to 3 at all time intervals in this study (Table 4). No statistically significant difference was noted on both mesial and distal papilla levels with respect to time (P  =  .91 and .85, respectively) (Table 4). At T4, more than 50% of the papilla fill was observed in 89% of all sites.

Despite the tearing of the facial gingival margin in 1 patient while preparing the recipient site for the SCTG, the result was inconsequential. Partial necrosis of the SCTG was observed in 2 patients. At T4, while one patient did not experience significant facial gingival tissue change, 1.0 mm of facial gingival recession was noted in the other patient.

During the provisional phase, 3 episodes of provisional restoration debonding, 4 fractured provisional restorations, and 1 abutment screw loosening were observed and resolved uneventfully.

The cumulative implant success rate following single immediate tooth replacement and SCTG in this study was 90% (9/10) after a follow-up period of 1 year. Although comparable implant success rates have been reported with single immediate tooth replacement without SCTG with a similar implant system (91% to 100%),32–45 it is slightly less than similar procedures performed without SCTG with other implant systems (98% to 100%).6,7,11–13,41,46–52 This is a consequence of the small sample size since each implant corresponds to 10% in the present case series.

Studies involving single implants have reported peri-implant marginal bone level changes from −0.2 mm to −1.0 mm for immediate tooth replacement procedures,7,11,13,41,47,51 and from −0.4 mm to −1.6 mm for delayed loaded procedures after the first year of function.9,53,54 It has been suggested that the “platform switching” feature could be beneficial in maintaining peri-implant MBL both mechanically (by reducing the force transmitted to the implant-bone interface) and biologically (by creating a better seal at the implant-abutment interface and relocating the inflammatory zone [inward] away from the bone).18 With regard to implant studies with the platform switching feature, MBL changes have ranged from 0 mm to −0.78 mm with a follow-up period of 6 to 57 months.32–45 In this study, the mean peri-implant MBL change of −0.31 mm at T4 was within the range of the aforementioned studies and other studies similar in nature.

Minimal mean facial gingival tissue recession (−0.5 to −0.8 mm) has been observed in short-term studies (1 to 2 years of follow-up) with immediate tooth replacement procedures.7,11,13 In this study, the viability of SCTG was examined in conjunction with immediate tooth replacement. Despite partial necrosis encountered in 2 patients, the overall mean FGL change was minimal at T4 (−0.05 mm) (Table 2). In fact, the mean FGL change of the remaining 7 implants without necrotic SCTG was +0.07 mm. This is similar to the data reported by Kan et al55 and Cornelini et al56 respectively, where a mean facial gingival tissue gain of 0.2 mm was observed 1 year following immediate implant placement with SCTG. This implies that SCTG in conjunction with immediate tooth replacement in the esthetic zone may be beneficial in minimizing facial gingival tissue recession when proper 3-dimensional implant position is achieved and bone graft is placed into the implant socket gap.55 Nevertheless, a high necrosis rate (2/10  =  20%) observed in this study also implied that bilaminar SCTG in conjunction with immediate tooth replacement procedures is a technique sensitive procedure with inherent risks that must not be overlooked.

The validity of the Periotest instrument has been the subject of debate; however, the PTV of an implant seems to provide an acceptable level of objectivity for diagnosing initial implant stability.26,57 It has been suggested that a PTV of −5 to +5 is required for proper osseointegration.26 Based on this, the mean PTV at T1 of −0.1 (range −2 to +5) reported in this study suggested that primary stability of some implants was not optimal. The high PTV may be related to the density/quality of the maxillary bone as well as to the immediate implant placement in an extraction site where implant stability relies mainly on the engagement of the apical and the palatal aspects of the anterior extraction socket.5 In addition, a statistically significant lower mean PTV was noted at T3 (−2; range −3 to −1), suggesting that osseointegration is a dynamic process and that the implant stability in this study improved over time.

While it is generally agreed that plaque accumulation can potentially induce a negative mucosal response,7 the relationship between compromised oral hygiene and implant failure has been contentious.58–63 The mPI scores observed throughout the duration of this study were either 0 or 1, implying that the patients were able to maintain a good level of oral hygiene (Table 3). To minimize the peri-implant gingival tissue disturbance following immediate tooth replacement and SCTG, the patients were advised to refrain from brushing the surgical site for 1 month. Meanwhile, the oral hygiene was adequately maintained through light swabbing of the surgical area with a cotton-tipped applicator soaked in 0.12% chlorhexidine gluconate (Peridex).

The PIS in the present study ranged from 0 to 3, at T1, T2, T3, and T4. There were no statistically significant differences in the PIS among different time intervals (Table 4; P > .05) when immediate tooth replacement with SCTG was performed, even when necrosis of the SCTG in 2 patients was observed. This validates the idea that the implant papilla level is dictated by the proximal bone level of the adjacent teeth,64,65 and the best way to maintain the papilla is to provide support immediately after tooth removal.4,5,7,66 

Although useful information was found in this study, due to the small sample size, its limitations should be acknowledged. Future studies involving a larger sample size with a control group and long-term follow-up will undoubtedly provide more useful information on the viability of this particular procedure.

When proper 3-dimensional implant position is achieved and bone graft is placed into the implant-socket gap, favorable success rate and peri-implant tissue response of platform switching implants can be achieved following immediate tooth replacement in conjunction with subepithelial connective tissue graft.

FGL

facial gingival level

IIPP

immediate implant placement and provisionalization

MBL

marginal bone level

mPI

modified plaque index

PIS

papilla index score

PTV

Periotest values

RL

reference line

SCTG

subepithelial connective tissue graft

This research was in partial fulfillment of an MS degree for the primary author.

The authors thank Biomet 3i, Warsaw, Ind, for providing the implants and related prosthetic components related to this research.