Current Concepts in Dental Implants: Clinical Assessment in the Prevention of Peri-implant Mucositis, Peri-implantitis, and Implant Failure
Course Number: 514
Post-treatment Clinical Evaluation and Care
A strict prophylaxis recare schedule should be established and maintained to monitor any changes. The patient is seen for comprehensive oral hygiene instructions and soft-tissue examination after the prosthesis is placed. Follow-up visits are scheduled as appropriate. At this appointment, the dental team reviews the adequacy of self-care procedures and re-evaluates the health of the peri-implant tissues. A three-month recare schedule is suggested for a one-year duration. Depending on the patient’s self-care and the individual’s current periodontal status, the patient may then be placed on a six-month recare schedule after the first year. During the first two years, no more than six months should elapse between recare visits.
The early detection, prevention, and treatment of peri-implant diseases are imperative for implant success. Peri-implant maintenance includes the proper placement of the dental implant, patient preventive self-care, and professional care by the dental team. The post-treatment goal is successful healing of the soft tissues and bone layers by creating a fibrous layer interposed between the implant and bone. Continual comprehensive clinical assessment and diagnoses of the post-treatment peri-implant tissues is key. This process includes identifying any current risk factors that may affect dental implants.9 The recare clinical examinations include questioning the patient about any pain or concerns, review of their medical status, and the evaluation of soft tissues and dental implant. The appropriate interval for the next appointment is determined based on a new clinical examination. At recare appointments, dental implants are examined for plaque and calculus accumulation around the implant and natural dentition, signs of inflammation and edema, peri-implant soft tissue color, consistency, and contour are also evaluated. Examination also includes palpation and percussion.9
In patients with healthy peri-implant tissues, the probing attachment levels are consistently found coronal to the alveolar crest. This indicates the presence of direct connective tissue contact to the dental implant surface. With healthy tissues, the probing depth measurement will be approximately 1.5 mm higher above the bone level.2 At inflamed sites, increased probing depths and reduced attachment levels may occur. Note that probing measurements can be inaccurate due to probe placement. The limitations in probing leads clinicians to depend on radiographic images and other forms of clinical assessment.23-24
Peri-implant soft tissues are similar in structure and clinical appearance as periodontal soft tissues. The soft tissues consist of epithelial and connective tissues. Implants have a gingival/mucosal sulcus, a long junctional epithelial attachment, with connective tissue above the supporting bone. However, dental implants do not have a periodontal ligament or inserting collagen fibers. Clinically, the thickness of the peri-implant soft tissues will vary from 2 mm or more.29 As with natural dentition, there is continuous epithelium around the implant with a sulcular epithelium that lines the inner surface of the gingival sulcus. The apical portion of the gingival sulcus is lined with long junctional epithelium. The zone of the supracrestal connective tissue fibers provides a seal to the outside oral environment.6The bone-to-implant interface with its rigidity can lead to biomechanical issues, as well as the healing of the soft tissue-to-implant interface influence long-term success of the dental implant.28
The presence of keratinized gingiva is not necessarily correlated to long-term stability. However, dental implants surrounded by nonkeratinized mucosa only may be more susceptible to peri-implant complications. Keratinized mucosa tends to be more firmly anchored to the periosteum by collagen fibers than nonkeratinized mucosa that has more elastic fibers making the tissue slightly mobile."26-27 When there is nonkeratinized tissue, patients may complain about pain while performing preventive self-care. The symptoms can be alleviated by increasing the amount of keratinized tissue around the implant with soft tissue grafting.29
Soft tissues surrounding dental implants also have the same inflammatory response to plaque accumulation as natural dentition. Polymorphonuclear and mononuclear cells transmigrate through peri-implant sulcular epithelium as does natural dentition. It is expected that 1.2 mm marginal bone loss occurs the first year after implant placement and 0.1 mm per year afterwards. However, higher levels of bone loss is abnormal. Pathologic bone loss can occur along the entire dental implant or around the crestal portion of the dental implant, indicating poor osseointegration, peri-implantitis, or occlusal stress.26-27,29
Dental implant movement impairs the differentiation of osteoblasts resulting in fibrous scar tissue forming between the implant and bone.26-27 It is imperative to avoid excessive forces, including occlusal loading during the early stages of healing. Multiunit implant restorations may be splinted to distribute the occlusal load maximizing implant support.2 Mobility of soft tissues, due to nonkeratinized tissue surrounding the dental implant is also associated with a higher incidence of implant failure.29 Occlusion should be checked at each recall appointment examination. Implant patients who brux or clench should receive an occlusal guard.
At each recare visit, the dental professional should perform a clinical assessment of peri-implant soft tissues by examining the color, surface texture, and note any bleeding and inflammation. When probing, the use of a non-metal periodontal probe will not contaminate the titanium surface, is gentle to tissue, and safe against damaging dental implant surfaces. Some clinical researchers suggest that periodontal probing be performed at infrequent intervals at one site (the same site each time) with light pressure. As with natural dentition, the dental professional must be careful not to contaminate the dental implant sulcus with bacteria from a diseased periodontal sulcus. It is recommended that the periodontal probe be dipped in chlorhexidine gluconate between periodontal probing measurements to avoid contamination.
When examining the implant, the dental professional must chart the presence of plaque and calculus deposits around the implant surfaces. The bacteria responsible for periodontitis are the same for peri-implantitis. These pathogenic bacteria are gram-negative anaerobic bacteria, including: Bacteroides forsythus, actinobacillus actinomycetemcomitans, porphyromonas gingivalis, and Treponema denticola shown to contribute to failing implant sites. After the soft tissue has been examined, the next step is to evaluate mobility of the implants, transmucosal abutments, and prosthetic superstructure. Seventy-eight percent of failing implants have excess mobility. Mastication or lack of tissue stability at the junction of the dental implant and connective tissue can cause apical migration of the junctional epithelium which in turn causes gingival recession, alveolar bone loss, and pocketing. The occlusion should be monitored at recare appointments to detect occlusal changes. Occlusal equilibration may be needed.
One of the most important pre and post-operative tools to evaluate the health and success of the dental implant is radiographic images. It is a reliable periodontal indices for evaluating failing implants. A mobile implant may display a narrow, radiolucent space surrounding the implant-bone interface. Radiographic images can assess bone height and density and show the functional relationship between the prosthesis, implant, and abutment components. It is suggested that radiographic images, excluding the baseline radiographic image taken one week post-surgery, be taken every three months after initial placement of the implant. After the first year, radiographic images should be taken once each year. It is recommended that CBCT imaging be used for measuring cortical bone thickness, as well as being utilized in post-operative imaging. However, past studies acknowledge its limitations such as overestimating the vertical distance between the top of the implant and the crestal bone.36
For dental implant plaque and calculus removal, only instruments that do not damage the implant surfaces may be used. In commercial use and form, pure is soft, non-magnetic, and passive. These metallic surfaces develop a layer of titanium oxide that does not undergo any further breakdown under physiologic situations. Damage can lead to changes in the surface chemistry of the material, resulting in corrosion. Surface roughness and corrosion facilitate plaque retention, ultimately compromising the implant. It is therefore imperative that no oral health maintenance procedure directly affect this titanium oxide surface layer.25
Conventional metal curettes cause considerable changes to the implant surface. Only instruments made of plastic, graphite, nylon, or those with a Teflon®-coating should be in contact with the implant. The use of a dissimilar metal (such as stainless steel) on titanium may lead to corrosion. The use of these dissimilar metals on implant surfaces have been studied *in vitro*, comparing the number of human gingival fibroblasts attaching to the surface of a commercially pure titanium-alloy curette. Results showed a significant reduction in the number of fibroblasts attaching to titanium implants that had been scaled with the stainless-steel curette when compared to the plastic and titanium scalers.33-34,39 Ultrasonic instrumentation continues to be contraindicated with dental implants. Ultrasonic scalers may severely disrupt the titanium dioxide surface, leading to a multitude of grooves and a roughened surface, which can lead to further plaque retention and a compromised implant. A study utilizing a modified ultrasonic instrument with a custom-designed delvin plastic tip showed that the standard ultrasonic instrument caused considerable scratching and gouging to the titanium implant.6 Shallow scratches made with the metal ultrasonic could be polished smooth, but the deeper scratches could not. The modified ultrasonic instrument produced noticeable but minimal changes that when polished did not appear to be microscopically different from the polished control. The modified ultrasonic instrument may be a promising device for maintenance of the dental implant. No definite answer can be made concerning ultrasonic use for implants at this time."7,22,25 Although air polishing on implant surfaces was controversial in the past, recent studies have shown air polishing to be effective and safe for maintenance procedures.
After calculus deposits have been removed, the prosthesis and abutments may be selectively polished with a rubber cup and a nonabrasive fine polishing paste. Rubber cup polishing alone appears to be the least abrasive treatment using a prophylaxis paste, commercial implant pastes, or tin-oxide. However, paste deposits will be left on the implant surfaces. A rubber point may also be used. After polishing, the implant, surfaces should be gently irrigated with water to avoid any adverse tissue healing. An antimicrobial solution should be applied to the peri-implant tissues.39
If a dental implant is displaying increased probing depths, bleeding, or any other indication of the onset of failure, a controlled drug delivery system can be applied. Applying slow-release minocycline hydrochloride spheres has shown clinical improvement within 12 months, including positive results with early cases of peri-implantitis.37