Oral Maxillofac Surg DOI 10.1007/s10006-016-0551-8
REVIEW ARTICLE
Complications related to bone augmentation procedures of localized defects in the alveolar ridge. A retrospective clinical study Anders Torp Jensen 1 & Simon Storgård Jensen 1 & Nils Worsaae 1
Received: 13 August 2015 / Accepted: 8 February 2016 # Springer-Verlag Berlin Heidelberg 2016
Abstract Purpose This retrospective clinical study aims to evaluate complications after augmentation of localized bone defects of the alveolar ridge. Methods From standardized registrations, the following complications related to bone augmentation procedures were recorded: soft tissue dehiscence, infection, sensory disturbance, additional augmentation procedures needed, and early implant failure. Results A total of 223 patients (132 women, 91 men; mean age 23.5 years; range 17–65 years) with 331 bone defects had bone augmentation performed into which 350 implants were placed. Soft tissue dehiscence occurred in 1.7 % after GBR procedures, 25.9 % after staged horizontal ridge augmentation, and 18.2 % after staged vertical ridge augmentation. Infections were diagnosed in 2 % after GBR procedures, 12.5 % after sinus floor elevation (SFE) (transcrestal technique), 5 % after staged SFE, 11 % after staged horizontal ridge augmentation, and 9 % after staged vertical ridge augmentation. Additional augmentation procedures were needed in 2 % after GBR procedures, 37 % after staged horizontal ridge augmentation, and 9 % after staged vertical ridge augmentation. A total of six early implant failures occurred (1.7 %), four after GBR procedures (1.6 %), and two (12 %) after staged vertical ridge augmentation.
* Anders Torp Jensen [email protected]
1
Department of Oral and Maxillofacial Surgery, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark
Conclusions Predictable methods exist to augment localized defects in the alveolar ridge, as documented by low complication rates and high early implant survival rates. Keywords Bone augmentation . Complications . Retrospective clinical study
Introduction Bone augmentation procedures are often indicated to allow implant placement in an optimal three-dimensional position to attain long-term function and predictable esthetic outcome for the later prosthetic restoration. The extent of atrophy of the alveolar crest dictates whether the bone augmentation procedures may be performed simultaneous with the implant placement or as a separate procedure [1, 2]. Atrophy of the alveolar crest may be the result of tooth agenesis, dental and maxillofacial trauma, periodontal disease, tooth extractions, tumor surgery, etc. and may take place in the horizontal as well as in the vertical dimension. Bone augmentation procedures may be performed with autogenous bone grafts, bone substitute materials, or combinations thereof so-called composite grafts. Autogenous bone grafts are still considered the gold standard in bone regeneration procedures [3, 4]. However, drawbacks of autografts include donor site morbidity, unpredictable resorption, and limited available volume [5]. Especially, extraorally harvested bone grafts are associated with clinically significant morbidity and risk of complications [6–9]. Therefore, whenever possible, intraoral donor sites are preferred. The most frequently applied bone augmentation techniques related to implant dentistry are guided bone regeneration (GBR) procedures [10]. In GBR procedures, a barrier membrane is utilized to allow bone to form without the interference
Oral Maxillofac Surg
of fibrous and epithelial tissues. The space created beneath the membrane may be grafted with autogenous bone, bone substitute materials, or composite grafts. In general, GBR procedures are performed simultaneously with implant placement in case of a thin facial bone wall, dehiscence-type defect, or fenestration-type defects. Staged GBR procedures are indicated in case of substantial horizontal and/or vertical ridge atrophy and most often include transplantation of an autogenous bone block to add additional mechanical support to the membrane and the covering soft tissues [10]. An alternative method to gain additional width of the alveolar crest is the ridge split procedure [11]. Ridge height may be increased by a vertical sandwich osteotomy [12] or by distraction osteogenesis [13]. Sinus floor elevation (SFE) is a well-documented technique to gain bone height in the atrophic posterior maxilla. The traditional SFE procedure includes preparation of a lateral window through which the sinus membrane is carefully elevated. If the residual bone height is 5 mm or more and the course of the sinus floor is relatively horizontal, the transcrestal technique—also known as the osteotome technique—can be used [14, 15]. The different bone augmentation techniques are well described in the literature. However, the range and rate of complications related to these procedures is less thorough documented. Complications related to bone augmentation procedures can arise intraoperatively, in the early, or in the late healing phase and may be located at augmented site or at the donor site if autogenous bone is used in the grafting protocol. The most frequently encountered postoperative complications include infections and soft tissue dehiscences, which may result in the need for additional grafting at a later surgical intervention or to implant failure. We hypothesize that predictable methods exist to augment localized bone defects of the alveolar ridge, characterized by low complication rates and providing sufficient conditions for simultaneous or staged implant placement. Therefore, the aim of the present retrospective study was to report on the complications after bone regeneration procedures of localized defects of the alveolar ridge performed simultaneously with implant placement or in a separate procedure and of implant survival rate before loading.
disability is offered free treatment. All surgeries were performed by two of the authors, both oral and maxillofacial surgeons (N.W. and S.S.J.) The following exclusion criteria were applied: patients with medical conditions that compromised general bone or soft tissue healing (i.e., diabetes, irradiation, antiresorptive agents), patients who also had orthognathic surgery, patients without follow-up data before prosthetic loading of the implants, and patients whose records lacked information about the study variables listed below. Local exclusion criteria included active periodontal disease, poor oral hygiene, and heavy smokers (>10 cigarettes daily). Finally, augmentations counted fewer than 5 were excluded. The distribution of included and excluded patients can be seen in Fig. 1. Based on standardized registration sheets for each patient, the following data were recorded: Age and gender of the patients. Number and survival of implants placed in the augmented bone. Two implant systems were used: Astra Osseospeed implants (Astra Tech AB, Mölndal, Sweden) and Straumann SLA implants (Institut Straumann AG, Basel, Switzerland). Type of bone augmentation procedure.
Material and methods
6) Staged vertical ridge augmentations included vertical sandwich osteotomies.
All patients were consecutively included in this study and had besides bone augmentations also dental implants inserted at the District Dental Care Unit, Capital Region, at the Department of Oral and Maxillofacial Surgery, University Hospital (Rigshospitalet), Copenhagen, Denmark, from January 1, 2004, to October 31, 2011. Since 2001, when a new law was passed in Denmark, patients with tooth agenesis and early trauma related tooth loss causing functional
1) GBR procedure performed simultaneously with the implant placement included grafted autogenous bone, bone substitute materials, and a resorbable membrane. 2) SFE (transcrestal technique) performed simultaneously with the implant placement performed when the residual bone height was between 5 and 7 mm and primary stability of the implant could be obtained. 3) SFE (lateral window technique) performed simultaneously with implant placement when residual bone height was below 8 mm, and primary stability of the implant could be obtained. 4) Staged SFE (lateral window technique) performed when primary stability of the implant could not be obtained simultaneously with the augmentation. 5) Staged horizontal ridge augmentation included a) On-lay bone block augmentations b) GBR procedures
The biomaterials used for the GBR procedures were deproteinized bovine bone mineral (DBBM) (BioOss, Geistlich, Wohlhusen, Switzerland) and a resorbable collagen membrane (BioGide, Geistlich, Wohlhusen, Switzerland), and for sandwich osteotomies, a coralderived hydroxyapatite block (ProOsteon 500, Biomet, Warsaw, IN, USA.)
Oral Maxillofac Surg
Fig. 1 Distribution of included and excluded patients
All bone augmentation procedures were performed using autogenous bone alone or in combination with DBBM. No allogenic bone was used. In GBR and SFE procedures, we aimed at a 1:1 ratio of autogenous bone and DBBM. All surgical procedures were performed using local anesthesia. Some patients in addition received oral sedation and some procedures were done in general anesthesia. All patients received prophylactic antibiotics (penicillin, clindamycin, or amoxicillin with clavulanic acid) initiated 1 h preoperatively with doses ranging from a one-shot prophylaxis up to 6 days postoperatively. Clorhexidine 0.12 % mouth rinse were instituted immediately before surgery and continued until suture removal 10 to 21 days postoperatively.
5. Implant failure in case of lack of osseointegration before loading.
Intraoperative perforation of the Schneiderian membrane during SFE (Fig. 5) was recorded but not characterized as a complication per se. The size of the bony defects and the quantitative success of the bone augmentation is not measured in this study. Due to the retrospective design of this study and the use of resorbable membranes and since all implants were inserted nonsubmerged, no reentry procedure was indicated to allow clinical evaluation of the augmented hard tissue volume.
Complications
Results Locations of complications were registered and were categorized as early if appearing within 21 days postoperatively, or late if they appeared after that period. Complications related to augmentation and implant procedures were registered using the following definitions: 1. Soft tissue dehiscence, when a separation of the suture line with exposure of the barrier membrane and/or the grafting material occurred (Figs. 2, 3, and 4) 2. Infection, characterized by pain, swelling, redness, fever, and/or purulent discharge that required additional antibiotic treatment. 3. Sensory disturbance if altered sensation of the facial skin was recorded more than 6 months after surgery. 4. Additional augmentation procedures needed at the time of implant placement to obtain sufficient implant stability and/or to create an optimal esthetic result after loss of graft or inadequate primary augmentation. If additional augmentation was planned initially as staged augmentations, it was not considered a complication.
Two hundred twenty-three patients, 132 women and 91 men, mean age 23.5 years (range 17–65 years) with 331 bone defects had bone augmentation procedures performed simultaneous with or prior to placement of 350 implants. Distribution of the patients, implant survival, and complications related to the augmentation procedures are listed in Table 1. 240 GBR procedures were performed in 171 patients simultaneous with insertion of 246 implants. Four implants placed in the augmented bone were lost. In five cases, an additional bone augmentation was necessary. Five infections (one early and four late) and four dehiscences were recorded (two early and two late). Three infections were directly correlated to three implant failures. SFE (transcrestal technique) was performed in eight patients with simultaneous placement of eight implants. No additional augmentations were made, and all implants survived. One early infection in a case with perforation was treated successfully with antibiotics.
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Fig. 2 Dehiscence 2 weeks after GBR of the lower anterior alveolar ridge using a combination of autogenous bone chips and deproteinized bovine bone mineral simultaneous with placement of two implants
SFE (lateral window technique) was performed in 21 patients with simultaneous placement of 26 implants in 25 augmentations. No implants were lost, and no additional grafting was needed. Six sinus membrane perforations and no postoperative infections were recorded. Staged SFE (lateral window technique) was performed in 20 sinuses in 17 patients. At second stage, 24 implants were inserted. No additional augmentation procedures were required, and all implants survived. Four perforations of the Schneiderian membrane were recorded. One early infection in a case with perforation was treated successfully with antibiotics. Staged horizontal ridge augmentation was performed in 23 patients with 27 bone defects. Autogenous bone blocks were utilized in 12 cases (with 15 blocks) and staged GBR was performed in 11 patients. At second stage, 29 implants were placed in the augmented bone. An additional bone augmentation procedure was indicated around ten of the implants (37 %). Seven dehiscences occurred (two early and five late). Infections developed at three sites (two early and one late). One patient suffered a temporary sensory disturbance (at the recipient site). No early implant failures were recorded. Staged vertical ridge augmentation using sandwich osteotomy was performed in 11 patients. A total of 17 implants were inserted at the 11 augmented sites. Two implants were lost. One patient needed an additional bone augmentation in the vertical dimension before implant placement. As
Fig. 3 Dehiscence of autogenous bone block 4 weeks after staged augmentation in the lower right first molar region
Fig. 4 Late exposure of coral-derived block used for sandwich osteotomy in the upper anterior region
preplanned, four patients required a supplemental GBR in the horizontal dimension simultaneous with the implant placement. One case of infection and two augmentations with dehiscences were recorded. The infection was correlated to one implant failure, and the two dehiscences were correlated to two additional augmentations in the vertical dimension. The complications rates for the different augmentation procedures ranged from 7.5 % when GBR was performed simultaneous with the implant placement to 74 % in the staged horizontal group. The dominating type of complication was the need of additional augmentation. Implant survival rates before loading were 100 % in the three SFE groups. In GBR performed simultaneous with the implant placement 98.4, and 100 %, and 88 % in staged horizontal and sandwich osteotomy, respectively. In total, six implants failed yielding an overall implant survival rate of 98.3 %. All failed implants were lost before prosthetic loading (mean 6 weeks postoperatively) five of the six
Fig. 5 Perforation of the Schneiderian membrane during sinus floor elevation using the lateral window technique
2/88 %
4/26 %
1 (4b)/9 %
failed implants were inserted in the upper anterior region, and no patients lost more than one implant. Nineteen of 21 additional augmentations were located in the anterior alveolar process, 16 in the maxilla and 3 in the mandible. The distribution of augmentations is listed in Table 2.
Discussion
Early, ≤21 days postoperatively; late, >21 days postoperatively
Additional horizontal augmentation b
a
Staged vertical ridge augmentation (Sandwich)
11
11
17
0
2/18 %
0
1/9 %
0
0/100 %
0/100 %
6/50 %
1
0 0
1/6.7 % 2/1.3 %
0 0
5/33 % 2/1.3 %
0 14
15 15
12 11
12 Bone block
0/100 % 10/37 % 27 23
29
2/7.4 %
5/18.5 %
2/7.4 %
1/3.7 %
1
0/100 % 0 0 0 1/5 % 0 0 20 17
24
0/100 % 0 0 0 0 0 0 25 21
26
0/100 % 0 0 0 1/12.5 % 0 0 8 8
8
4/98.4 % 5/2 % 0 4/1.7 % 1/0.4 % 2/0.8 %
Earlya
2/0.8 % 246 240 171
GBR procedure performed simultaneous with the implant placement SFE simultaneous with implant placement (transcrestal technique) SFE simultaneous with implant placement (lateral window technique) Staged SFE (lateral window technique) Staged horizontal ridge augmentation Particulate
Table 1
Complications
Patients
Augmentations
Implants
Late Earlya
Late
No.
Implant failures No./survival rate Infections No./% Dehiscences No./%
Sensory disturbances
Additional augmentation No/%
Oral Maxillofac Surg
The results from the present retrospective study indicate that localized bone defects in the alveolar ridge can be augmented predictably with high implant survival rates and few complications. However, larger defects requiring staged augmentation procedures in the horizontal and/or vertical dimensions seem to be associated with an increased number of complications. A GBR procedure was performed simultaneous with implant placement whenever primary stability of the implant could be accomplished in an ideal 3D position for the later prosthetic rehabilitation. At the preprosthetic examination, 3 to 6 months postoperatively, the periimplant hard tissue conditions were judged satisfactory in 98 % of the cases. This is in accordance with a previous systematic review reporting 5 % soft tissue complications after augmentation of fenestration- and dehiscence-type bone defects using resorbable membranes [16]. Soft tissue dehiscences or infections in the early postoperative phase preceded three (43 %) of the five cases in our study where additional bone grafting in a separate surgical procedure was indicated. Early implant failure was recorded in four of the remaining 246 implants insertions yielding an implant survival rate of 98.4 %, which is comparable to previous systematic reviews on implants with a textured implant surface placed in grafted or nongrafted bone [10, 17]. This supports the assumption that when primary implant stability can be attained, the implant is very likely to osseointegrate. GBR procedures were performed using DBBM with a low substitution rate in combination with autogenous bone particles and a collagen membrane. This procedure is documented clinically, by cone beam CT, and histologically to sustain long-term stability of the augmented volume [18, 19]. However, since resorbable membranes were utilized and implants were inserted nonsubmerged, no reentry procedure was indicated to allow clinical evaluation of the augmented hard tissue volume. The low percentage of cases that needed additional grafting may thus be a reflection of sufficient case selection and predictable surgical technique. However, the present retrospective clinical dataset does not allow firm conclusions to be drawn on this aspect. No early implant failures were observed after SFE using the lateral window technique or transcrestal approach, confirming SFE to be a safe and predictable method to in-
Oral Maxillofac Surg Table 2 Distribution of augmentations GBR procedure performed simultaneous with the implant placement Staged horizontal ridge augmentation Particulate Bone block Staged vertical ridge augmentation (Sandwich)
Anterior maxilla
Posterior maxilla
Anterior mandible
Posterior mandible
198/83 %
11/5 %
15/6 %
18/8 %
18/67 %
0
5/19 %
4/15 %
9/75 %
0
1/8 %
2/17 %
9/60 % 4/36 %
0 3/27 %
4/27 % 1/9 %
2/13 % 3/27 %
Anterior: incisors and canines; posterior: premolars and molars
crease vertical bone height in the posterior maxilla [10, 15]. Two early postoperative infections (4.3 %) where observed— one after transcrestal SFE and one after SFE using the staged lateral window technique. This is comparable to previously reported infection rates after SFE [20, 21]. Both infections were successfully treated with antibiotics alone. Perforation of the Schneiderian membrane was observed intraoperatively in ten cases (22.2 %) during SFE using the lateral window technique, which is in line with previous reports of perforation rates in systematic reviews [10, 22]. Any perforation of the Schneiderian membrane was repaired with a collagen membrane. The incidence of sinus membrane perforations in the staged SFE and SFE with simultaneous implant placement was 20 and 24 %, respectively, which is in agreement with another retrospective clinical study that reported a perforation rate of 19 % for staged and 32 % SFE with simultaneous implant placement [23]. It has been debated whether intraoperative perforation of the Schneiderian membrane increases the risk of postoperative infection, loss of grafting material and implant [20, 21, 24]. No such tendency could be identified in the present material. Most of the staged horizontal ridge augmentations needed substantial additional hard tissue and was therefore performed using onlay autogenous bone blocks harvested from intraoral donor sites. The most frequently encountered complication was the need for additional augmentation at the time of implant placement. Additional augmentation was necessary in 50 % of the cases where a mixture of particulated autogenous bone and DBBM was used and 26 % of the bone block cases. A systemic review reported additional augmentation in 26.6 % of cases using a particulate augmentation protocol and in 4.7 % of the bone block cases [10]. The tendency of more stable conditions using cortical bone blocks from intraoral donor sites as compared to an augmentation protocol using particulate grafting materials alone was thus confirmed. The explanation has mainly been attributed to the instability of the particulate graft due to mucosal pressure and mechanical load [25, 26]. All staged augmentations included the use of
DBBM particles and a resorbable collagen membrane, which has been documented predictably to reduce but not eliminate surface resorption [27, 28]. Dehiscence and/or postoperative infection preceded three out of four cases where additional augmentation procedures were needed in the bone block group. The increased risk of bone block resorption in case of dehiscence is well described [29], which underlines the importance of meticulous soft tissue handling and tension free soft tissue closure. An early implant survival rate of 100 % found in the present material is in accordance with previous systematic reviews reporting survival rates between 96.8 and 100 % after staged horizontal ridge augmentation [10, 30]. Localized ridge augmentation in the vertical dimension is reported to be one of the most challenging procedures with a high complication rate [10, 16]. Especially in cases of previous dento-alveolar trauma, the partially edentulous alveolar process may present atrophy in both height and width. Onlay block grafts may augment both dimensions. However, compromised soft tissue conditions often makes this approach less feasible, and a sandwich osteotomy or distraction osteogenesis may be indicated. By these procedures, two separate surgeries are usually planned to correct the vertical and horizontal component of the defects, respectively. Four additional augmentations in the horizontal dimension at the time of implant placement in the present material, is, therefore, an expected finding confirmed by other studies and is not considered a complication [12]. On the other hand, one of 11 patients (9 %) needed an additional vertical augmentation before implant insertion was possible. Three patients developed a late dehiscence or infection, which is in accordance with complication rates reported in previous studies [31, 32]. Two out of 18 implants failed before final prosthetic restoration yielding an early implant survival rate of 88 %, which is relatively low compared to previous studies [32]. In summary, the present data confirms vertical ridge augmentation to be a challenging clinical procedure in which a higher risk of complications and implant failure should be anticipated.
Oral Maxillofac Surg
In general, predictable methods exist to augment localized defects in the alveolar ridge, as documented by low complication rates and high early implant survival rates, especially in cases where the extent of atrophy allows implant placement with simultaneous bone augmentation. In cases where staged horizontal and/or vertical augmentations are indicated, an increased complication rate should be anticipated. SFE, staged or simultaneous with implant placement, is documented to be a safe and predictable method to increase vertical bone height in the posterior maxilla accompanied by few complications and high implant survival rates.
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REVIEW ARTICLE
Complications related to bone augmentation procedures of localized defects in the alveolar ridge. A retrospective clinical study Anders Torp Jensen 1 & Simon Storgård Jensen 1 & Nils Worsaae 1
Received: 13 August 2015 / Accepted: 8 February 2016 # Springer-Verlag Berlin Heidelberg 2016
Abstract Purpose This retrospective clinical study aims to evaluate complications after augmentation of localized bone defects of the alveolar ridge. Methods From standardized registrations, the following complications related to bone augmentation procedures were recorded: soft tissue dehiscence, infection, sensory disturbance, additional augmentation procedures needed, and early implant failure. Results A total of 223 patients (132 women, 91 men; mean age 23.5 years; range 17–65 years) with 331 bone defects had bone augmentation performed into which 350 implants were placed. Soft tissue dehiscence occurred in 1.7 % after GBR procedures, 25.9 % after staged horizontal ridge augmentation, and 18.2 % after staged vertical ridge augmentation. Infections were diagnosed in 2 % after GBR procedures, 12.5 % after sinus floor elevation (SFE) (transcrestal technique), 5 % after staged SFE, 11 % after staged horizontal ridge augmentation, and 9 % after staged vertical ridge augmentation. Additional augmentation procedures were needed in 2 % after GBR procedures, 37 % after staged horizontal ridge augmentation, and 9 % after staged vertical ridge augmentation. A total of six early implant failures occurred (1.7 %), four after GBR procedures (1.6 %), and two (12 %) after staged vertical ridge augmentation.
* Anders Torp Jensen [email protected]
1
Department of Oral and Maxillofacial Surgery, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark
Conclusions Predictable methods exist to augment localized defects in the alveolar ridge, as documented by low complication rates and high early implant survival rates. Keywords Bone augmentation . Complications . Retrospective clinical study
Introduction Bone augmentation procedures are often indicated to allow implant placement in an optimal three-dimensional position to attain long-term function and predictable esthetic outcome for the later prosthetic restoration. The extent of atrophy of the alveolar crest dictates whether the bone augmentation procedures may be performed simultaneous with the implant placement or as a separate procedure [1, 2]. Atrophy of the alveolar crest may be the result of tooth agenesis, dental and maxillofacial trauma, periodontal disease, tooth extractions, tumor surgery, etc. and may take place in the horizontal as well as in the vertical dimension. Bone augmentation procedures may be performed with autogenous bone grafts, bone substitute materials, or combinations thereof so-called composite grafts. Autogenous bone grafts are still considered the gold standard in bone regeneration procedures [3, 4]. However, drawbacks of autografts include donor site morbidity, unpredictable resorption, and limited available volume [5]. Especially, extraorally harvested bone grafts are associated with clinically significant morbidity and risk of complications [6–9]. Therefore, whenever possible, intraoral donor sites are preferred. The most frequently applied bone augmentation techniques related to implant dentistry are guided bone regeneration (GBR) procedures [10]. In GBR procedures, a barrier membrane is utilized to allow bone to form without the interference
Oral Maxillofac Surg
of fibrous and epithelial tissues. The space created beneath the membrane may be grafted with autogenous bone, bone substitute materials, or composite grafts. In general, GBR procedures are performed simultaneously with implant placement in case of a thin facial bone wall, dehiscence-type defect, or fenestration-type defects. Staged GBR procedures are indicated in case of substantial horizontal and/or vertical ridge atrophy and most often include transplantation of an autogenous bone block to add additional mechanical support to the membrane and the covering soft tissues [10]. An alternative method to gain additional width of the alveolar crest is the ridge split procedure [11]. Ridge height may be increased by a vertical sandwich osteotomy [12] or by distraction osteogenesis [13]. Sinus floor elevation (SFE) is a well-documented technique to gain bone height in the atrophic posterior maxilla. The traditional SFE procedure includes preparation of a lateral window through which the sinus membrane is carefully elevated. If the residual bone height is 5 mm or more and the course of the sinus floor is relatively horizontal, the transcrestal technique—also known as the osteotome technique—can be used [14, 15]. The different bone augmentation techniques are well described in the literature. However, the range and rate of complications related to these procedures is less thorough documented. Complications related to bone augmentation procedures can arise intraoperatively, in the early, or in the late healing phase and may be located at augmented site or at the donor site if autogenous bone is used in the grafting protocol. The most frequently encountered postoperative complications include infections and soft tissue dehiscences, which may result in the need for additional grafting at a later surgical intervention or to implant failure. We hypothesize that predictable methods exist to augment localized bone defects of the alveolar ridge, characterized by low complication rates and providing sufficient conditions for simultaneous or staged implant placement. Therefore, the aim of the present retrospective study was to report on the complications after bone regeneration procedures of localized defects of the alveolar ridge performed simultaneously with implant placement or in a separate procedure and of implant survival rate before loading.
disability is offered free treatment. All surgeries were performed by two of the authors, both oral and maxillofacial surgeons (N.W. and S.S.J.) The following exclusion criteria were applied: patients with medical conditions that compromised general bone or soft tissue healing (i.e., diabetes, irradiation, antiresorptive agents), patients who also had orthognathic surgery, patients without follow-up data before prosthetic loading of the implants, and patients whose records lacked information about the study variables listed below. Local exclusion criteria included active periodontal disease, poor oral hygiene, and heavy smokers (>10 cigarettes daily). Finally, augmentations counted fewer than 5 were excluded. The distribution of included and excluded patients can be seen in Fig. 1. Based on standardized registration sheets for each patient, the following data were recorded: Age and gender of the patients. Number and survival of implants placed in the augmented bone. Two implant systems were used: Astra Osseospeed implants (Astra Tech AB, Mölndal, Sweden) and Straumann SLA implants (Institut Straumann AG, Basel, Switzerland). Type of bone augmentation procedure.
Material and methods
6) Staged vertical ridge augmentations included vertical sandwich osteotomies.
All patients were consecutively included in this study and had besides bone augmentations also dental implants inserted at the District Dental Care Unit, Capital Region, at the Department of Oral and Maxillofacial Surgery, University Hospital (Rigshospitalet), Copenhagen, Denmark, from January 1, 2004, to October 31, 2011. Since 2001, when a new law was passed in Denmark, patients with tooth agenesis and early trauma related tooth loss causing functional
1) GBR procedure performed simultaneously with the implant placement included grafted autogenous bone, bone substitute materials, and a resorbable membrane. 2) SFE (transcrestal technique) performed simultaneously with the implant placement performed when the residual bone height was between 5 and 7 mm and primary stability of the implant could be obtained. 3) SFE (lateral window technique) performed simultaneously with implant placement when residual bone height was below 8 mm, and primary stability of the implant could be obtained. 4) Staged SFE (lateral window technique) performed when primary stability of the implant could not be obtained simultaneously with the augmentation. 5) Staged horizontal ridge augmentation included a) On-lay bone block augmentations b) GBR procedures
The biomaterials used for the GBR procedures were deproteinized bovine bone mineral (DBBM) (BioOss, Geistlich, Wohlhusen, Switzerland) and a resorbable collagen membrane (BioGide, Geistlich, Wohlhusen, Switzerland), and for sandwich osteotomies, a coralderived hydroxyapatite block (ProOsteon 500, Biomet, Warsaw, IN, USA.)
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Fig. 1 Distribution of included and excluded patients
All bone augmentation procedures were performed using autogenous bone alone or in combination with DBBM. No allogenic bone was used. In GBR and SFE procedures, we aimed at a 1:1 ratio of autogenous bone and DBBM. All surgical procedures were performed using local anesthesia. Some patients in addition received oral sedation and some procedures were done in general anesthesia. All patients received prophylactic antibiotics (penicillin, clindamycin, or amoxicillin with clavulanic acid) initiated 1 h preoperatively with doses ranging from a one-shot prophylaxis up to 6 days postoperatively. Clorhexidine 0.12 % mouth rinse were instituted immediately before surgery and continued until suture removal 10 to 21 days postoperatively.
5. Implant failure in case of lack of osseointegration before loading.
Intraoperative perforation of the Schneiderian membrane during SFE (Fig. 5) was recorded but not characterized as a complication per se. The size of the bony defects and the quantitative success of the bone augmentation is not measured in this study. Due to the retrospective design of this study and the use of resorbable membranes and since all implants were inserted nonsubmerged, no reentry procedure was indicated to allow clinical evaluation of the augmented hard tissue volume.
Complications
Results Locations of complications were registered and were categorized as early if appearing within 21 days postoperatively, or late if they appeared after that period. Complications related to augmentation and implant procedures were registered using the following definitions: 1. Soft tissue dehiscence, when a separation of the suture line with exposure of the barrier membrane and/or the grafting material occurred (Figs. 2, 3, and 4) 2. Infection, characterized by pain, swelling, redness, fever, and/or purulent discharge that required additional antibiotic treatment. 3. Sensory disturbance if altered sensation of the facial skin was recorded more than 6 months after surgery. 4. Additional augmentation procedures needed at the time of implant placement to obtain sufficient implant stability and/or to create an optimal esthetic result after loss of graft or inadequate primary augmentation. If additional augmentation was planned initially as staged augmentations, it was not considered a complication.
Two hundred twenty-three patients, 132 women and 91 men, mean age 23.5 years (range 17–65 years) with 331 bone defects had bone augmentation procedures performed simultaneous with or prior to placement of 350 implants. Distribution of the patients, implant survival, and complications related to the augmentation procedures are listed in Table 1. 240 GBR procedures were performed in 171 patients simultaneous with insertion of 246 implants. Four implants placed in the augmented bone were lost. In five cases, an additional bone augmentation was necessary. Five infections (one early and four late) and four dehiscences were recorded (two early and two late). Three infections were directly correlated to three implant failures. SFE (transcrestal technique) was performed in eight patients with simultaneous placement of eight implants. No additional augmentations were made, and all implants survived. One early infection in a case with perforation was treated successfully with antibiotics.
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Fig. 2 Dehiscence 2 weeks after GBR of the lower anterior alveolar ridge using a combination of autogenous bone chips and deproteinized bovine bone mineral simultaneous with placement of two implants
SFE (lateral window technique) was performed in 21 patients with simultaneous placement of 26 implants in 25 augmentations. No implants were lost, and no additional grafting was needed. Six sinus membrane perforations and no postoperative infections were recorded. Staged SFE (lateral window technique) was performed in 20 sinuses in 17 patients. At second stage, 24 implants were inserted. No additional augmentation procedures were required, and all implants survived. Four perforations of the Schneiderian membrane were recorded. One early infection in a case with perforation was treated successfully with antibiotics. Staged horizontal ridge augmentation was performed in 23 patients with 27 bone defects. Autogenous bone blocks were utilized in 12 cases (with 15 blocks) and staged GBR was performed in 11 patients. At second stage, 29 implants were placed in the augmented bone. An additional bone augmentation procedure was indicated around ten of the implants (37 %). Seven dehiscences occurred (two early and five late). Infections developed at three sites (two early and one late). One patient suffered a temporary sensory disturbance (at the recipient site). No early implant failures were recorded. Staged vertical ridge augmentation using sandwich osteotomy was performed in 11 patients. A total of 17 implants were inserted at the 11 augmented sites. Two implants were lost. One patient needed an additional bone augmentation in the vertical dimension before implant placement. As
Fig. 3 Dehiscence of autogenous bone block 4 weeks after staged augmentation in the lower right first molar region
Fig. 4 Late exposure of coral-derived block used for sandwich osteotomy in the upper anterior region
preplanned, four patients required a supplemental GBR in the horizontal dimension simultaneous with the implant placement. One case of infection and two augmentations with dehiscences were recorded. The infection was correlated to one implant failure, and the two dehiscences were correlated to two additional augmentations in the vertical dimension. The complications rates for the different augmentation procedures ranged from 7.5 % when GBR was performed simultaneous with the implant placement to 74 % in the staged horizontal group. The dominating type of complication was the need of additional augmentation. Implant survival rates before loading were 100 % in the three SFE groups. In GBR performed simultaneous with the implant placement 98.4, and 100 %, and 88 % in staged horizontal and sandwich osteotomy, respectively. In total, six implants failed yielding an overall implant survival rate of 98.3 %. All failed implants were lost before prosthetic loading (mean 6 weeks postoperatively) five of the six
Fig. 5 Perforation of the Schneiderian membrane during sinus floor elevation using the lateral window technique
2/88 %
4/26 %
1 (4b)/9 %
failed implants were inserted in the upper anterior region, and no patients lost more than one implant. Nineteen of 21 additional augmentations were located in the anterior alveolar process, 16 in the maxilla and 3 in the mandible. The distribution of augmentations is listed in Table 2.
Discussion
Early, ≤21 days postoperatively; late, >21 days postoperatively
Additional horizontal augmentation b
a
Staged vertical ridge augmentation (Sandwich)
11
11
17
0
2/18 %
0
1/9 %
0
0/100 %
0/100 %
6/50 %
1
0 0
1/6.7 % 2/1.3 %
0 0
5/33 % 2/1.3 %
0 14
15 15
12 11
12 Bone block
0/100 % 10/37 % 27 23
29
2/7.4 %
5/18.5 %
2/7.4 %
1/3.7 %
1
0/100 % 0 0 0 1/5 % 0 0 20 17
24
0/100 % 0 0 0 0 0 0 25 21
26
0/100 % 0 0 0 1/12.5 % 0 0 8 8
8
4/98.4 % 5/2 % 0 4/1.7 % 1/0.4 % 2/0.8 %
Earlya
2/0.8 % 246 240 171
GBR procedure performed simultaneous with the implant placement SFE simultaneous with implant placement (transcrestal technique) SFE simultaneous with implant placement (lateral window technique) Staged SFE (lateral window technique) Staged horizontal ridge augmentation Particulate
Table 1
Complications
Patients
Augmentations
Implants
Late Earlya
Late
No.
Implant failures No./survival rate Infections No./% Dehiscences No./%
Sensory disturbances
Additional augmentation No/%
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The results from the present retrospective study indicate that localized bone defects in the alveolar ridge can be augmented predictably with high implant survival rates and few complications. However, larger defects requiring staged augmentation procedures in the horizontal and/or vertical dimensions seem to be associated with an increased number of complications. A GBR procedure was performed simultaneous with implant placement whenever primary stability of the implant could be accomplished in an ideal 3D position for the later prosthetic rehabilitation. At the preprosthetic examination, 3 to 6 months postoperatively, the periimplant hard tissue conditions were judged satisfactory in 98 % of the cases. This is in accordance with a previous systematic review reporting 5 % soft tissue complications after augmentation of fenestration- and dehiscence-type bone defects using resorbable membranes [16]. Soft tissue dehiscences or infections in the early postoperative phase preceded three (43 %) of the five cases in our study where additional bone grafting in a separate surgical procedure was indicated. Early implant failure was recorded in four of the remaining 246 implants insertions yielding an implant survival rate of 98.4 %, which is comparable to previous systematic reviews on implants with a textured implant surface placed in grafted or nongrafted bone [10, 17]. This supports the assumption that when primary implant stability can be attained, the implant is very likely to osseointegrate. GBR procedures were performed using DBBM with a low substitution rate in combination with autogenous bone particles and a collagen membrane. This procedure is documented clinically, by cone beam CT, and histologically to sustain long-term stability of the augmented volume [18, 19]. However, since resorbable membranes were utilized and implants were inserted nonsubmerged, no reentry procedure was indicated to allow clinical evaluation of the augmented hard tissue volume. The low percentage of cases that needed additional grafting may thus be a reflection of sufficient case selection and predictable surgical technique. However, the present retrospective clinical dataset does not allow firm conclusions to be drawn on this aspect. No early implant failures were observed after SFE using the lateral window technique or transcrestal approach, confirming SFE to be a safe and predictable method to in-
Oral Maxillofac Surg Table 2 Distribution of augmentations GBR procedure performed simultaneous with the implant placement Staged horizontal ridge augmentation Particulate Bone block Staged vertical ridge augmentation (Sandwich)
Anterior maxilla
Posterior maxilla
Anterior mandible
Posterior mandible
198/83 %
11/5 %
15/6 %
18/8 %
18/67 %
0
5/19 %
4/15 %
9/75 %
0
1/8 %
2/17 %
9/60 % 4/36 %
0 3/27 %
4/27 % 1/9 %
2/13 % 3/27 %
Anterior: incisors and canines; posterior: premolars and molars
crease vertical bone height in the posterior maxilla [10, 15]. Two early postoperative infections (4.3 %) where observed— one after transcrestal SFE and one after SFE using the staged lateral window technique. This is comparable to previously reported infection rates after SFE [20, 21]. Both infections were successfully treated with antibiotics alone. Perforation of the Schneiderian membrane was observed intraoperatively in ten cases (22.2 %) during SFE using the lateral window technique, which is in line with previous reports of perforation rates in systematic reviews [10, 22]. Any perforation of the Schneiderian membrane was repaired with a collagen membrane. The incidence of sinus membrane perforations in the staged SFE and SFE with simultaneous implant placement was 20 and 24 %, respectively, which is in agreement with another retrospective clinical study that reported a perforation rate of 19 % for staged and 32 % SFE with simultaneous implant placement [23]. It has been debated whether intraoperative perforation of the Schneiderian membrane increases the risk of postoperative infection, loss of grafting material and implant [20, 21, 24]. No such tendency could be identified in the present material. Most of the staged horizontal ridge augmentations needed substantial additional hard tissue and was therefore performed using onlay autogenous bone blocks harvested from intraoral donor sites. The most frequently encountered complication was the need for additional augmentation at the time of implant placement. Additional augmentation was necessary in 50 % of the cases where a mixture of particulated autogenous bone and DBBM was used and 26 % of the bone block cases. A systemic review reported additional augmentation in 26.6 % of cases using a particulate augmentation protocol and in 4.7 % of the bone block cases [10]. The tendency of more stable conditions using cortical bone blocks from intraoral donor sites as compared to an augmentation protocol using particulate grafting materials alone was thus confirmed. The explanation has mainly been attributed to the instability of the particulate graft due to mucosal pressure and mechanical load [25, 26]. All staged augmentations included the use of
DBBM particles and a resorbable collagen membrane, which has been documented predictably to reduce but not eliminate surface resorption [27, 28]. Dehiscence and/or postoperative infection preceded three out of four cases where additional augmentation procedures were needed in the bone block group. The increased risk of bone block resorption in case of dehiscence is well described [29], which underlines the importance of meticulous soft tissue handling and tension free soft tissue closure. An early implant survival rate of 100 % found in the present material is in accordance with previous systematic reviews reporting survival rates between 96.8 and 100 % after staged horizontal ridge augmentation [10, 30]. Localized ridge augmentation in the vertical dimension is reported to be one of the most challenging procedures with a high complication rate [10, 16]. Especially in cases of previous dento-alveolar trauma, the partially edentulous alveolar process may present atrophy in both height and width. Onlay block grafts may augment both dimensions. However, compromised soft tissue conditions often makes this approach less feasible, and a sandwich osteotomy or distraction osteogenesis may be indicated. By these procedures, two separate surgeries are usually planned to correct the vertical and horizontal component of the defects, respectively. Four additional augmentations in the horizontal dimension at the time of implant placement in the present material, is, therefore, an expected finding confirmed by other studies and is not considered a complication [12]. On the other hand, one of 11 patients (9 %) needed an additional vertical augmentation before implant insertion was possible. Three patients developed a late dehiscence or infection, which is in accordance with complication rates reported in previous studies [31, 32]. Two out of 18 implants failed before final prosthetic restoration yielding an early implant survival rate of 88 %, which is relatively low compared to previous studies [32]. In summary, the present data confirms vertical ridge augmentation to be a challenging clinical procedure in which a higher risk of complications and implant failure should be anticipated.
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In general, predictable methods exist to augment localized defects in the alveolar ridge, as documented by low complication rates and high early implant survival rates, especially in cases where the extent of atrophy allows implant placement with simultaneous bone augmentation. In cases where staged horizontal and/or vertical augmentations are indicated, an increased complication rate should be anticipated. SFE, staged or simultaneous with implant placement, is documented to be a safe and predictable method to increase vertical bone height in the posterior maxilla accompanied by few complications and high implant survival rates.
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