A systematic review of the incidence of biological and technical complications in implant dentistry reported in prospective longitudinal studies of at least 5 years

OBJECTIVE

To systematically review the incidence of biological and technical complications in implant therapy reported in prospective longitudinal studies of at least 5 years.

METHODS

A MEDLINE search was conducted for prospective longitudinal studies with follow-up periods of at least 5 years. Screening and data abstraction were performed independently by multiple reviewers. The types of complications assessed were as follows: implant loss, sensory disturbance, soft tissue complications, peri-implantitis, bone loss >or=2.5 mm, implant fracture and technical complications related to implant components and suprastructures.

RESULTS

The search provided 1310 titles and abstracts, out of which 159 were selected for full-text analysis. Finally, 51 studies were included. Meta analysis of these studies indicated that implant loss prior to functional loading is to be expected to occur in about 2.5% of all implants placed in implant therapy including more than one implant and when routine procedures are used. Implant loss during function occurs in about 2-3% of implants supporting fixed reconstructions, while in overdenture therapy >5% of the implants can be expected to be lost during a 5-year period. Few studies (41% of those included) reported data on the incidence of persisting sensory disturbance >1 year following implant surgery. Most of the studies that provided such data reported on the absence or a low incidence (1-2%) of this complication beyond this interval. A higher incidence of soft tissue complications was reported for patients treated with implants supporting overdentures. There is limited information regarding the occurrence of peri-implantitis and implants exhibiting bone loss >or=2.5 mm. Implant fracture is a rare complication and occurs in <1% of all implants during a 5-year period. The incidence of technical complications related to implant components and suprastructures was higher in overdentures than in fixed reconstructions.

CONCLUSION

Implant loss was most frequently described (reported in about 100% of studies), while biological complications were considered in only 40-60% and technical complications in only 60-80% of the studies. This observation indicates that data on the incidence of biological and technical complications may be underestimated and should be interpreted with caution.

[The surgical complications of dental implants]

Replacing missing teeth with osseointegrated dental implants is a predictable technique as evidenced by the overall five-year implant survival rates ranging 93% to 97%. Few studies, however, address systematically the frequency or natural history of complications related to the use of dental implants. Reported complication rates range so widely, i.e. 1%-40%, as to be rendered clinically meaningless. Differences in reported rates may be attributable to differing definitions of complications. Even less has been written about risk factors for developing surgical complications related to the use of dental implants. Knowledge regarding the type and frequency of complications that can occur with implants is an important aspect of treatment planning, surgeon-patient communication, informed consent and post-treatment care. The purposes of this chapter are to: 1) summarize the reported types and frequencies of implant-associated complications, 2) identify risk factors for developing complications associated with the use of dental implants, and 3) to suggest strategies to avoid complications.

[Nerve injury following implant placement: prevention, diagnosis and treatment modalities]

Nerve injury is a well-known complication following oral and maxillofacial surgery. Direct trauma, inflammation and infection are postoperative neural disturbances main causes. The most inflicted nerves associated with endosseous implant placement are those innervating the mandible: the inferior alveolar nerve, the mental nerve and the lingual nerve. Evaluation of the nerve injury characteristics and severity as early as possible has always imposed a great challenge for clinicians. We demonstrate a reliable yet simple way of dealing with this kind of problem in conjunction with comparing preoperative and postoperative sensation of the chin, the tongue and the lower lip. On the other hand, it is considerably important to take preventive measures for such injuries by using appropriate radiographic images. If a nerve damage has occurred, best prognosis is to be expected by early and appropriate treatment. It is imperative to treat such injuries in four months following the injury, otherwise a permanent nerve damage may occur. Further investigation of nerve damage risks following implant placement should be performed in order to enable patient to decide whether having implants dependent rehabilitation or choosing an alternative.

[Differential diagnosis and treatment strategies for peri-implant diseases]

The aim of this article is to discuss the requirements to prevent, intercept and treat the peri-implant diseases at different stages. The ethiology and pathogenesis of peri-implant disease is presented, followed by definition and characteristics of the two main entites: peri-implant mucositis and peri-implantitis. Data and concepts regarding various evaluation parameters, such as pocket probing depth, bleeding on probing, gingival and plaque scores, radiographic and mobility which should be used to assess the clinical status of the peri-implant environment are discussed. The detection and treatment of early pathogenic changes during regular recall maintenance visits can prevent peri-implant soft tissue inflammation and progressive bone loss. The biologic rationale and guidelines for therapeutic procedures aimed to prevent and arrest the Peri-implant Disease according to a maintenance system termed Comulative Interceptive Supportive Therapy (CIST) is presented. The CIST protocol includes as a first sequence mechanical antiseptic and antibiotic treatment to control ongoing infection. Following this, peri-implant bony lesion may be corrected by regenerative or resective surgical techniques.

IN CONCLUSION

By continuing diagnosis during maintenance, developing peri-implant infections can be controlled successfully by providing mechanical, antiseptic, antibiotic and surgical supportive therapy, individually or combined.

Treatment of peri-implant infections: a literature review

OBJECTIVES

The purpose of the present paper is to review available information on the treatment of peri-implant mucositis and peri-implantitis.

MATERIALS AND METHODS

The results of animal research and human studies are presented. Proposed strategies for the treatment of peri-implantitis presented in the literature are also included.

RESULTS

Most of the information accessible at this time derives from case reports. The reports provide evidence that efforts to reduce the submucosal infection may result in short-term improvements of the peri-implant lesion. They also indicate that regenerative procedures in intrabony peri-implant defects can result in the formation of new bone.

CONCLUSIONS

Several uncertainties remain regarding the treatment of peri-implantitis. Properly conducted long-term follow-ups of consecutively treated cases would seem to be a realistic avenue for accumulation of more information. This may assist in establishing the predictability, magnitude and stability of improvements that can be achieved.

Bone contact around acid-etched implants: a histological and histomorphometrical evaluation of two human-retrieved implants

The surface characteristics of dental implants play an important role in their clinical success. One of the most important surface characteristics of implants is their surface topography or roughness. Many techniques for preparing dental implant surfaces are in clinical use: turning, plasma spraying, coating, abrasive blasting, acid etching, and electropolishing. The Osseotite surface is prepared by a process of thermal dual etching with hydrochloric and sulfuric acid, which results in a clean, highly detailed surface texture devoid of entrapped foreign material and impurities. This seems to enhance fibrin attachment to the implant surface during the clotting process. The authors retrieved 2 Osseotite implants after 6 months to repair damage to the inferior alveolar nerve. Histologically, both implants appeared to be surrounded by newly formed bone. No gaps or fibrous tissues were present at the interface. The mean bone-implant contact percentage was 61.3% (+/- 3.8%).

Osteoclast activity around loaded and unloaded implants: a histological study in the beagle dog

The mechanisms of bone loss around dental implants are poorly understood. The osteoclast is the most important bone-resorbing cell. Humoral factors seem able to stimulate the differentiation of osteoclasts from mononuclear phagocytes. Bacterial lipopolysaccharides seem to be directly involved in inflammatory bone loss by stimulation of the survival and fusion of preosteoclasts. Excessive load seems to be able to cause bone loss. The aim of this paper was to evaluate the presence and number of osteoclasts in peri-implant bone in control (unloaded) and test (loaded) implants in order to determine if loading per se could be a contributing factor in peri-implant bone resorption. Forty-eight implants were inserted in the mandibles of 4 beagle dogs. After 3 months, a prosthetic superstructure was inserted on 24 implants, whereas in 24 implants only the healing screws were positioned. Twenty-four implants (12 test and 12 control) were retrieved at 6 months, and 24 implants (12 test and 12 control) were retrieved at 12 months. All implants were osseointegrated. The number of osteoclasts found in the crestal bone in the first 3 mm from the implant surface was evaluated. The mean number of osteoclasts were the following: control implants (6 months), 5.66 +/- 0.81; control implants (12 months), 2.55 +/- 1.05; test implants (6 months), 5.25 +/- 1.55; and test implants (12 months), 2.5 +/- 1.0. No statistically significant differences were observed between the control and test implants. According to our data, loading does not seem to have a relevant importance on the osteoclast activation in peri-implant bone.

Ailing and failing endosseous dental implants: a literature review

Although the overall success rate of implant dentistry is very high, dental implants occasionally fail. It is essential for the clinician to recognize unhealthy implants and to determine whether they are ailing, failing, or failed prior to beginning any salvage efforts. Ailing and failing implants are amenable to therapy. Implants diagnosed as failed should be removed. This review provides the reader with information on non-surgical and surgical therapies available for managing ailing and failing implants. Undoubtedly, the best steps to avoid encountering ailing or failing implants involve proper case selection, excellent surgical technique, placing an adequate restoration on the implant, educating the implant patient to maintain meticulous oral hygiene, and evaluating the implant both clinically and radiographically at frequent recall visits.

[Proposed solution after complications with an immediately loaded implant supported cantilever bridge. A case report]

As an effort to reduce the treatment time in dental implantology, immediate loading has received increasing attention during the past years. The success of early and immediate loading of implants in the interforaminal region is well documented in the dental literature. However, early loading of implants still bears an increased risk. Therefore, strict patient selection is needed. In this case report the rehabilitation of a patient with an immediately loaded implant-supported cantilever fixed partial denture in the mandible is presented. The occurrence of complications few weeks after loading lead to the explantation of two of the five implants. As a consequence, the patient was restored with an implant-retained overdenture.

Patient's informed consent prior to implant-prosthetic treatment: a retrospective analysis of expert opinions

PURPOSE

The purpose of this retrospective analysis of expert opinions was to optimize the level of patient information prior to implant-prosthetic treatment.

MATERIALS AND METHODS

Twenty-eight expert opinion reports on implant treatment cases compiled between 1996 and August 2001 were analyzed.

RESULTS

Seventy-five percent of all cases subjected to expert opinion reports revealed generally inadequate patient information. Significant associations were found between diagnostic mistakes and a lack of or inadequate information about complications that occurred (P = .04). Inadequate prosthetic or periodontal pretreatment of the patient prior to implant treatment was associated with a lack of information concerning implant and periodontal maintenance (P = .023) as well as insufficient oral hygiene status (P = .001).

DISCUSSION

In addition to a general lack of patient information, a lack of information about possible complications and inadequate information about treatment risks, treatment costs, and treatment alternatives were also found.

CONCLUSION

Optimization of pretreatment information for patients, as well as improvement of communication with patients throughout the whole treatment and maintenance period, seem to be necessary.

A study of dental implants in medically treated hypothyroid patients

PURPOSE

The purpose of this study was to investigate the success outcomes of implants and prosthodontic treatment placed in patients with a previous history of hypothyroidism that was being controlled with medications.

MATERIALS AND METHODS

Twenty-seven female patients with a medically confirmed history of primary hypothyroid disease who were on replacement medications at the time of implant surgery were selected as the study group. They were matched with 29 control patients by age, gender, location (jaw and zone) of implants, type of prosthesis, and dental status of the opposing arch. Additional factors studied were medical history, medications, smoking habits, and bone quality and quantity.

RESULTS

There was no statistical difference in the number of implant failures between the two groups (p = .781). The hypothyroid patients had more soft tissue complications (p = .018) following stage 1 surgery. More bone loss around implants in the hypothyroid patients was recorded after year 1 of loading when compared with loss in their matched controls (p = .017).

CONCLUSIONS

This study suggests that medically controlled hypothyroid female patients treated with dental implants are not at higher risk of implant failure when compared with matched controls, and that a history of controlled hypothyroidism does not appear to be a contraindication for implant therapy with endosseous implants.

The segmental osteotomy in the management of malposed implants: a case report and literature review

BACKGROUND

The segmental osteotomy provides an important treatment approach for the correction of skeletal-dental malocclusions that would otherwise be unmanageable with conventional orthodontic care. The combined use of orthodontics and orthognathic surgery also has been adapted for use in the correction of developmental and traumatic deformities. Severely malpositioned implant fixtures may not permit restorative correction even with custom prosthetic appliances. As an alternative to implant removal, which can be associated with significant alveolar destruction, orthognathic surgery may offer a treatment modality to improve fixture alignment, thereby enabling a more favorable esthetic and functional prosthesis. This paper presents a case report and review of the segmental osteotomy procedure.

METHODS

A 32-year-old female with congenitally missing maxillary lateral incisors underwent implant surgery for prosthetic replacement of these teeth. Due to severe labial positioning of the implant fixtures, acceptable prosthetic treatment was not possible. A segmental osteotomy procedure was used to reposition the implants. The implants were splinted using a ridged interim suprastructure during the 4-month healing period. An occlusal appliance also was worn during the initial 8 weeks of this healing period.

RESULTS

The surgical procedure permitted intrusion and palatal repositioning of the implants. Healing proceeded with no untoward effects. Clinical findings at second-stage surgery were consistent with complete osseous repair and integration of the fixtures. Successful prosthetic treatment was subsequently completed for the patient.

CONCLUSION

The segmental osteotomy may provide an alternative treatment to the removal of severely malposed implants or their compromised prosthetic restoration.

Clinical classification of bone defects concerning the placement of dental implants

The goal of this classification of bone defects related to dental implant placement is to help clinicians accurately discuss proposed treatment regimens and organize treatment for clinical correction. A further goal of this effort to categorize bone defects requiring bone augmentation for implant placement is to standardize terminology to allow for more accurate dental communication. The five most encountered categories of bony defects are described.

A one-stage approach for nonsubmerged implants using a xenograft in narrow ridges: report on seven cases

In narrow alveolar ridges, dehiscences can occur at the time of implant placement. This report describes several cases in which buccal dehiscences at one-stage, nonsubmerged ITI implants were covered with deproteinized bovine bone mineral (Bio-Oss) and a nonresorbable e-PTFE membrane. The dehiscences ranged from 5 to 8.5 mm. The head of the implant perforated the membrane and was not covered by the mucoperiosteal flap. Membranes were removed after 12 to 20 weeks. One of the seven implants failed to osseointegrate. In four cases, no residual defect was found (100% coverage). In two cases, 63.5% and 87.5% coverage was obtained, respectively. At follow-up, 1 year and 5 months to 4 years and 7 months after placement and after loading, clinical probing depth never exceeded 3.5 mm. Radiographically, no resorption was found. In selected cases, dehiscences at the time of placement of nonsubmerged one-stage implants can be successfully treated using deproteinized bovine bone in combination with stiff, nonresorbable membranes.

Maxillary bone growth and implant positioning in a young patient: a case report

The literature supports the efficacy of osseointegrated implants for partially edentulous patients, but care must be exercised in adolescents with incomplete bone formation. Implants do not follow the normal growth of the jaws, and they behave like ankylosed teeth. They may also interfere with the normal growth of the alveolar process and jeopardize the germs of the adjacent permanent teeth or alter eruption. This case report analyzes the unfavorable clinical and radiographic findings of a single-tooth replacement in a young male over a 15-year period.

Delayed onset of altered sensation following dental implant placement and mental block local anesthesia: a case report

A case of a delayed-onset post-operative altered sensation of the mental nerve is reported with speculations as to etiology. There is a discussion concerning intraoperative radiographs and osteotomy positioning. When postoperative altered sensation occurs, etiologic considerations should always include local anesthetic administration technique. The importance of pulp testing from the first molar to the contralateral lateral incisor is key to determining whether the deficit is in the mandibular nerve or only the mental nerve, which may be a result of mental block local anesthetic administration and not implant placement. This differentiation may be important in treatment and/or legal exposure. The altered sensation was probably caused by the mental block anesthetic technique. The partial anesthetic area in this case was probably a result of crossover innervation from the contralateral mental nerve.

Effect of barrier membranes and autologous bone grafts on ridge width preservation around implants

BACKGROUND

The purpose of this study was to explore the effect of barrier membranes and autologous bone grafts on the preservation of ridge width around implants.

MATERIALS AND METHODS

Sixty-one patients were chosen from a database of case series; treatment assignment was based on clinical judgment. The patients received a total of 76 implants: 34 implants with guided tissue regeneration procedures, 27 with autologous bone grafts, and 15 without ridge preservation procedures (control group).

RESULTS

The ridge width around the 76 implants decreased an average of 1.4 mm (95% CI, -1.9 to -1.1 mm). Implants placed with autologous bone grafts or membranes tended to have worse outcomes. When compared to the no augmentation group, implants placed with guided tissue regeneration and autologous bone grafts resulted in 0.1 mm of additional bone loss (95% CI, -1.7 to -1.5 mm; p < .93) and 0.8 mm of additional bone loss (95% CI, -2.3 to 0.7 mm; p < .28), respectively.

CONCLUSIONS

Autologous graft procedures or barrier membranes do not appear to improve crestal ridge preservation around implants.

[Bioresorbable barrier membranes for guided bone regeneration around dental implants]

The aim of this study was to evaluate the efficacy of two bioresorbable barriers especially produced for guided bone regeneration. Six beagle dogs were used in this investigation. At the beginning of the study, all mandibular premolars were extracted and after a healing period of three months three screw-type machined implants were inserted in each side of the mandible. At the buccal aspect of each implant bed a dehiscence type defect with a coronoapical and mesiodistal extension of 5 mm was created. Then, one of the following four methods for defect treatment was applied: 1) guided bone regeneration (GBR) with a bioresorbable barrier (poly-L/DL-lactide) (test group 1), 2) GBR with a bioresorbable composite barrier [poly-L/DL-lactide reinforced with tricalciumphosphate (TCP)] (test group 2), 3) GBR with an expanded polytetrafluoroethylene barrier (GTAM) (control group 1), and 4) no treatment (control group 2). The animals were sacrificed six months after implant installation. During the healing period the most common problems encountered in the test groups 1 and 2 were soft tissue dehiscences and bioresorbable membrane exposures. Retrieved tissue specimens were processed for histological and histometric evaluation. The mean amount of vertical bone regeneration at the defect areas was 1.75 mm for test group 1, 1.82 mm for the test group 2, 2.38 mm for control group 1, and 1.93 mm for control group 2. When the amount of bone regeneration in contact to the implant surface was evaluated, the regeneration result was 1.45 mm for test group 1, 1.49 mm for test group 2, 2.08 mm for control group 1, and 0.91 mm for control group 2. For both measurements, no statistically significant differences could be observed between the different groups. The present animal experiment showed that the treatment of dehiscence type defects around machined implants with the two bioresorbable barriers showed only slightly superior results compared to the treatment without barriers (control group 2). The best results--although not statistically significant different from the other treatment groups--were obtained when nonresorbable barriers were used.

Persistent acute inflammation at the implant-abutment interface

The inflammatory response adjacent to implants has not been well-investigated and may influence peri-implant tissue levels. The purpose of this study was to assess, histomorphometrically, (1) the timing of abutment connection and (2) the influence of a microgap. Three implant designs were placed in the mandibles of dogs. Two-piece implants were placed at the alveolar crest and abutments connected either at initial surgery (non-submerged) or three months later (submerged). The third implant was one-piece. Adjacent interstitial tissues were analyzed. Both two-piece implants resulted in a peak of inflammatory cells approximately 0.50 mm coronal to the microgap and consisted primarily of neutrophilic polymorphonuclear leukocytes. For one-piece implants, no such peak was observed. Also, significantly greater bone loss was observed for both two-piece implants compared with one-piece implants. In summary, the absence of an implant-abutment interface (microgap) at the bone crest was associated with reduced peri-implant inflammatory cell accumulation and minimal bone loss.

Comparative analysis of collagen membranes for the treatment of implant dehiscence defects

Guided bone regeneration (GBR) evolved from the concept of guided tissue regeneration (GTR) and has been used for reconstructing sites with bone deficiencies associated with dental implants. For GBR, the use of absorbable collagen membranes has been increasing, but, at present, scientific information on the use of collagen membranes for GBR is limited. This study was aimed to clinically and histomorphometrically compare two collagen membranes, Bio-Gide(R) and BioMend ExtendTM, for the treatment of implant dehiscence defects in eight mongrel dogs. Implant dehiscence defects were surgically created in edentulous ridges, followed by the placement of three endosseous implants bilaterally in the mandible. Each implant dehiscence defect was randomly assigned to one of three treatment groups: (1) control (no membrane), (2) porcine dermis collagen barrier (Bio-Gide) or (3) bovine tendon collagen barrier (BioMend Extend). Dogs were sacrificed at 4 and 16 weeks (four dogs each) after treatment. Histomorphometric analysis included percentage linear bone fill (LF), new bone-to-implant contact (BIC) and area of new bone fill (BF). The results of the study revealed no significant differences among groups for any parameter at 4 weeks. However, at 16 weeks, more LF, BIC, and BF were noted in the membrane-treated groups than controls. BioMend Extend-treated defects demonstrated significantly greater BIC than control (P < 0.05) at this time point. BIC at 16 weeks was significantly greater than 4-week BIC (P < 0.05). Membrane exposure occurred in 9 out of 15 sites examined, resulting in significantly less LF and BIC than the sites without membrane exposure (P < 0.05). The results of this study indicate that: (1) GBR treatment with collagen membranes may significantly enhance bone regeneration, manifested at late stage (16 weeks) of healing; and (2) space maintenance and membrane coverage were the two most important factors affecting GBR using bioabsorbable collagen membranes.

Management of an implant case that required retreatment: a case report

The presented case represents how the lack of a preoperative panoramic radiograph or any radiograph contributed to incorrect case planning, poor implant selection, and the careless surgical placement of an implant into or dangerously close to the lower left mental foramen, resulting in a paresthesia of 9 months duration. Two implants were surgically removed and the bone defects were grafted with a mixture of irradiated cancellous bone plus Biogran. One implant was sectioned and intentionally "put to sleep." The case was successfully completed with a lower bar overdenture supported by 4 screw implants placed in alternate sites, opposing a custom fabricated maxillary denture with a lingualized occlusal scheme.

[Medical rehabilitation of patients with atrophic jaws]

The results of this study indicate that subperiosteal implants extend the potentialities of treatment for patients with significant maxillary bone atrophy fitted with permanent dentures.

Implant complications and failures: the fixed prosthesis

The implant-retained fixed prosthesis has been advocated as an effective restoration offering significant benefits over conventional prosthetics. The success of treatment depends on careful pre-surgical planning and prosthesis design. This paper outlines some common complications encountered during the planning, fabrication and maintenance of both large and small fixed prostheses and suggests how these complications can be minimized.