1. INTRODUCTION
The scientific knowledge associated with the constant advancement of biomaterials has provided dentistry with a wide range of rehabilitation options in the past decades. Implants and the advancement of tissue engineering have allowed the replacement of one or more missing teeth with high biologic and esthetic predictability. Developments in science and medicine have increased the longevity of human beings.
Before Brånemark established osseointegration, the survival rate of implants was much lower than today. Additionally, the indication for implants was restricted to complete edentulous patients. However, different treatment modalities today have variable survival and success rates for total, partial, and single rehabilitation ranging above 90%.
Nevertheless, new technologies have been employed to reduce the number of surgical and restorative procedures, often concerned only with short-term outcomes. The longevity of dental treatment and possible future changes that may occur, both biologically and technically, must be considered during a treatment plan. It is also necessary to consider how the patient ages and the systemic and local repercussions caused over time.
The focus of implantology has evolved from mainly achieving osseointegration and not considering soft tissues to contemporary implantology, which encompasses both the functional and esthetic aspects of treatment. Implant-supported restorations should mimic the natural dentition associated with longevity. However, there are no systematic studies that present consistent data on follow-up, survival, and success rates after 10 or 20 years of masticatory function. This raises the following question: What should we expect from our treatments after this time?
OBJECTIVES
At the end of the chapter the reader should be able to:
-
Understand the long-term success and survival rate of implants.
-
Characterize the types of failures in implant-supported prostheses.
-
Identify possible tissue modifications around teeth and implants.
2. SCIENTIFIC BACKGROUND
2.1. LONG-TERM SURVIVAL AND SUCCESS RATES OF IMPLANTS
Currently, the option of restoring function and esthetics with the use of implants is routine in dental offices; therefore, patients and clinicians should expect complications from the biologic behavior of these implants as well as mechanical responses of the materials used. Success in implant dentistry initially characterized by Albrektsson et al1 consisted of a clinical and radiographic evaluation of an asymptomatic implant (Table 01). The exclusive analysis of these characteristics is now considered as assessment of survival. The concept of success encompasses broader aspects of the implant system, prosthesis, and peri-implant tissues, in addition to patient satisfaction (Table 02). Figures 01A–C to 04A–D, respectively show implants classified as unsuccessful and successful.
|
SURVIVAL CRITERIA |
|---|
|
Clinically stable implant |
|
Absence of pain, infection, discomfort, or paresthesia |
|
Absence of radiolucent image around the implant |
|
Bone loss < 0.2 mm annually after first year |
Table 01. Success criteria initially proposed by Albrektsson et al1, which are now considered as implant survival criteria
|
SUCCESS CRITERIA2 |
|
|---|---|
|
IMPLANT |
– No pain, mobility, or suppuration – Bone loss < 1.5 mm in the first year – Bone loss < 0.2 mm annually after the first year – No radiolucent imaging around the implant |
|
PERI-IMPLANT SOFT TISSUES |
– Probing depth < 3 mm – No bleeding, suppuration, edema, or recession – Plaque index < 20% – Thickness of keratinized mucosa > 1.5 mm |
|
IMPLANT-SUPPORTED RESTORATION |
– No complications or prosthetic failures – Adequate esthetics and function |
|
PATIENT SATISFACTION |
– No discomfort and paresthesia – Satisfaction with esthetics – Adequate chewing and gustatory function – Overall satisfaction |
Table 02. Criteria commonly used to define success after implant rehabilitation. Adapted from Papaspyridakos et al2
01. A–C This patient had an immediate implant placed in the anterior maxilla that did not osseointegrate. Six months after the surgical procedure, the implant and provisional presented mobility, presence of a facial fistula, and the patient reported pain (A). Radiographically, it was possible to verify a radiolucent image around the implant, indicating failure (B, C).
02. A–J Implant in the anterior region with 10 years of follow-up in a 21-year-old patient. Initial clinical aspect of facial defect (A–C). Aspect of the remaining bone tissue (D). Fixation of autogenous bone fragment removed from the ascending ramus of the mandible (E). Covering of autogenous graft with synthetic graft and collagen membrane (F). After 6 months, it was possible to observe the improvement of the defect with (G) and without the provisional (H). Periapical radiograph after the healing period (I); note full integration of the autogenous graft (J).
03. A–J A 4.1 × 13 mm implant placed with nano-topography (A). Three-dimensional positioning (B). Silk suture (C). After 4 months of healing (D, E). Occlusal aspect with considerable increase in facial volume (F). Removal of healing abutment and healthy conditions of peri-implant tissues (G). Placement of the metal-ceramic abutment (H). Abutment control radiograph (I). Try-in of the zirconia copings (J).
04. A–D Placement of ceramic crowns (A). Clinical aspect of the 1-year follow-up (B). Lateral view of the 5-year follow-up with maintenance of the facial contour (C). Peri-implant bone crest after 5 years. Tooth-implant diastema after 10 years (D).
Longevity rates and biologic and technical risks should be considered for the treatment planning of unitary, partial, or total arches3. The durability of treatments is not based in how many years implants remain in the oral cavity, but how they work, remain esthetic, and allow proper maintenance and hygiene. Longitudinal studies evaluating survival rates of osseointegrated implants show rates above 85% in the first 5 years and 80% after 10 years of function. These data are based on the absence of mobility, clinically apparent disease, and bone loss of 0.2 mm radiographically detected annually1.
Considering other elements of evaluation of effectiveness and esthetic excellence, such as papillary height and the color of the peri-implant mucosa, single implants are an efficient treatment method, with survival rates of 98% over 5 years and 95% over 10 years4. It is necessary to consider the differences between the definitions of survival and success. Gallucci et al5 demonstrated 95.5% survival in a group of patients. When considering the success criteria regarding peri-implant tissue, prosthetic aspects, and subjective parameters, the same index dropped to 86.7%. The treated sites must be biologically prepared and healthy. Implant-supported restorations should have designs favorable to long-term maintenance, that is, the presence of interproximal contact points, hygiene areas, and an adequate emergence profile. Prior planning, mastery of the restorative techniques and materials employed (Figs 05A–D), as well as periodic maintenance, are crucial to achieving longevity in implant-supported rehabilitations.
05. A–D Adequacy of the vertical occlusion dimension concomitantly with placement of an implant-supported complete denture. Note the large discrepancy between before (A, B) and after the rehabilitation (C, D).
This chapter describes the problems most frequently reported in systematic reviews that address a follow-up period of 5–10 years and clinical observations of the authors with a follow-up of 10–20 years. First, the preventive procedures before implant placement are addressed, then the biologic risks and technical complications. Finally, the biologic role of residual maxillomandibular growth and occlusal changes in areas with previously placed implants is considered (Table 03).
Table 03. Aspects covered in this chapter
2.2. PREVENTION BEFORE IMPLANT PLACEMENT
2.2.1. SOFT TISSUE-RELATED ASPECTS
The gingival biotype is directly related to the longevity and stability of the tissue around the implants because they react differently to inflammatory aggression. A thin biotype around implants increases the risk of peri-implant margin recession. A thick biotype has excellent tissue stability in long-term follow-up6; therefore, in the anterior region, the presence of a thick biotype is essential to maintain soft tissue architecture over time (Figs 06A–C).
06. A–C Patient without attached gingiva and vestibule depth (A), without attached gingiva and with adequate vestibule depth (B), and with attached gingiva and adequate vestibule depth (C).
Many implants are placed in regions that have only alveolar mucosa, which differs from the attached gingiva in several ways. In addition to the absence of keratinized epithelium, this mucosa is frail, in part because of its low collagen content and the presence of large amounts of elastic fibers7,8. The parallel orientation of the fibers in the peri-implant tissue favors the rapid progression of peri-implant disease, affecting bone tissue and promoting its resorption.
Numerous studies argued that the presence or absence of keratinized tissue does not interfere with the health of peri-implant tissues provided that there is good hygiene9–11. On the other hand, our clinical experience shows that the presence of keratinized mucosa facilitates biofilm control around peri-implant tissues, especially the junctional epithelium, which remain free of inflammation. If all fresh sockets were submitted to regenerative procedures to maintain bone and gingival contour before being rehabilitated with implants, a high number of reconstructions could be avoided (Figs 07A–H to 11A–H).
07. A–H Single implant and temporary unit with tissue regeneration to maintain tissue architecture: initial clinical aspect (A); initial tomographic images, with sagittal (B), frontal (C), and axial (D) cuts. Clinical aspect after removal of the provisional (E). Oblique and longitudinal root fracture with a history of amalgam retrograde filling (F). Probing after the extraction; the depth (G) and presence of a defect on the buccalaspect are verified (H).
08. Position of a guide pin to check the depth and inclination of the perforation (A). A 3.5 × 13 mm tapered implant, with Morse connection (B). Occlusal view after implant installation (C). Immediate provisional screwed in after tissue regeneration (D). Clinical aspect 6 months after surgery (E). Removing the temporary abutment (F) and installing a zirconia abutment (G). Radiographic image of the abutment in position (H) and 12 months after surgery (I).
09. A–H Patient with loss of maxillary teeth and the entire structure of the maxillary ridge. Initial aspect of the patient’s smile (A), who had undergone orthognathic surgery, extraoral graft, and implant installation (B, C). Lip muscle insertion at the implant level due to the previous procedures (D–F). Due to the present condition, the prosthesis was not made. There was an indication of the deepening of the vestibule associated with the epithelial graft. For higher stability of the vestibule deepening procedure, and protection of the donor and recipient areas, a surgical drain was constructed. An impression of the distal implants was taken (G). A reduction was madeon the plaster model (H).
10. A–H Two UCLA abutments were placed in the distal implants (A, B) to make the surgical drip where the cement could flow through; this device was fixed by the distal implants (C, D). The muscle insertion was then removed, the vestibule was deepened (E, F), and the epithelium was removed from the tissue adjacent to the implants (G). A free gingival graft was removed from the hard palate and received vertical cuts to increase its extension (H).
11. A–H Due to the large extent of the area to be grafted, the graft was divided into two and stabilized at the buccal surface of the implants (A). The surgical drip was loaded with surgical cement and screwed into the distal implants to protect the recipient and donor regions (B). Tissue aspect at 15 (C) and 30 (D) days postoperatively. Note the increased attached gingiva around the implants 4 months after surgery (E, F). Appearance after maxillary rehabilitation: due to peri-implant problems, removal of the left mandibular implants was recommended (G). Control radiograph 3 years after the gingival graft (H). Gingival graft procedure: Dr Fausto Frizzera; rehabilitation procedure: Oral Surgery Residency Program at FOAr-UNESP.
Soft tissues around single implants are more stable and predictable than around multiple contiguous implants. In single implants, the position of soft tissue in proximal areas is maintained by the periodontal support of the adjacent tooth. In multiple implants, papillary formation only becomes predictable and with better esthetic results where there is a broad section of keratinized tissue.
2.2.2. OCCLUSION-RELATED ASPECTS
Stay updated, free dental videos. Join our Telegram channel
VIDEdental - Online dental courses
