Keeping dental implants healthy
One of the most important factors for long-term success of dental implants is the maintenance of healthy peri-implant tissues.
In today’s market, patients are more keen to have implant-borne prostheses than a conventional fixed or removable prosthesis. Therefore it is very important that all underlying dental disease is treated or stabilised before implant therapy can commence. This is of great importance when dealing with patients who are susceptible to periodontal disease – this group of patients has an increased susceptibility to peri-implantitis (1).
Peri-implantitis has been associated with oral pathogens, which are comparable to those associated with periodontal disease (2). Placing dental implants in partially dentate patients leads to the formation of a biofilm which has a different ecology to that of edentulous patients. Placing implants in untreated periodontally susceptible patients has been shown to increase the risk of peri-implantitis, therefore indicating spread of periodontal pathogens from untreated periodontal pockets (3).
It is essential to be methodical when monitoring the peri-implant tissues at review appointments to spot the early signs of peri-implantitis. The clinical markers that are used to assess the presence and severity of inflammation around the implant are:
• Plaque and calculus accumulation
• Inflammation of the peri-implant tissues
• Increase in peri-implant probing depths
• Bleeding on probing
• Suppuration from the peri-implant pocket
• Implant mobility
• Radiographic changes
• Resonance frequency analysis changes.
When probing peri-implant tissues a light force must be used (0.25Ncm) to avoid trauma to the tissues. There is no evidence to show that this light force will damage the implant surface or the junctional epithelium (4). There is a parallel attachment of the junctional epithelium around the implant surface, therefore there is less resistance when probing around the implant. This will result in deeper peri-implant probing depths compared to probing around natural teeth.
Peri-implant probing depths of implants are placed in sites excluding the aesthetic zone range between 2-4mm under healthy conditions. In the aesthetic zone where the implant is usually placed deeper, the probing depths are greater than the normal range. Therefore it is essential to record the initial baseline values should there be any change at a later date. Probing depths need to be recorded from a fixed landmark such as the abutment implant junction, so that if any changes do occur they can be noted from the previous record (5).
It is important to establish a baseline radiograph to record the bone levels at the time of the prosthesis placement. It has been suggested that long cone radiographs taken annually for the first three years of the implant in function is seen as reasonable. Thereafter the indications for further radiographs should be made following methodical clinical assessment.
It is accepted that most implant systems show evidence of a small amount of marginal bone loss within the first year of function (6). Smoking has been shown to be a risk factor to affect the long-term prognosis of dental implants. A high failure rate was noted in smokers compared to non-smokers in a six-year follow-up study (7). It is essential to monitor any clinical changes around dental implants and to act promptly.
If there is evidence of on-going bone loss it is important to ascertain the cause. The causes of progressive bone loss are occlusal overload and bacterial induced inflammation.
Bacterial induced inflammation is initially treated non-surgically but depends on the initial clinical presentation. This involves the removal of dental plaque with or without the use of locally delivered or systemic adjuncts. Lesions with probing depth of 5mm or more and bone loss of greater than 2mm would need surgical intervention, as recommended by the ITI consensus report (Figure 1).
Resective or regenerative surgeries are proposed for the treatment of peri-implantitis, depending on the anatomy of the bone defect surrounding the implant (8). If a site has a suprabony defect or a one-walled defect, it has been suggested that resection with osseous surgery and apically repositioned flaps should be performed (9).
The main aims of resective surgery are:
• To eliminate the inflammatory tissues
• To stop the disease from progressing further
• To maintain the implant in function with healthy peri-implant tissues
• To reduce the peri-implant pocket depths
• To gain a soft tissue morphology that allows cleansiblity for the patient and leads to healthy peri-implant tissues. At present there is no reliable evidence for preferring one type of treatment modality over another for failing implants (10).
It is important that good oral hygiene is performed to maintain healthy peri-implant tissues. The use of toothbrushes, either manual or electric, helps reduce the amount of plaque biofilm. Floss including superfloss and interdental brushes is essential for access interproximally. In the aesthetic zone, if the implants have been placed in the ideal position, a cross over flossing technique can be used (figure 5).
A poor flossing technique, or no flossing at all, can lead to subgingival inflammation of the peri-implant tissues (Figure 6), and a good subgingival flossing technique will result in formation of epithelialised sulcular tissue down to the implant neck (Figure 7). It is essential that, if a cement retained crown is placed, then all the cement is removed as subgingival irritants such as excess cement can provoke an acute peri-implantitis which can lead to soreness, swelling, bleeding on probing and bone loss (11).
It is important to watch the patient perform the oral hygiene technique and to review the patient two weeks after the final fit of the prosthesis, as they could be heavy handed, causing damage to the peri-implant tissues (Figure 8). If so, the technique needs to be modified. In some instances the patient can produce a self-induced peri-implantitis.
If the implant placement is not in an ideal position, this can lead to some difficulty in cleaning as the prosthesis may have a ridge-lap profile. In these cases, modification of the oral hygiene is necessary and the use of a tufted brush or superfloss is often indicated. In premolar and molar areas, the use of floss in the case of single unit implant, and in fixed-bridge prosthesis the use of superfloss and interdental brushes, is indicated.
Calculus formation on dental implants is very similar to that found on teeth, the only difference being that the abutment and the porcelain are very highly polished so the calculus is not tenacious. When removing supragingival calculus from the implant crowns, it is very important not to use stainless steel scalers as this will damage the titanium surfaces. Therefore it is recommended that you use a material that is softer than titanium – either gold-plated or reinforced plastic instruments.
Good oral hygiene performed by the patient has a significant effect on the stability of the marginal bone around dental implants. Poor oral hygiene in edentulous patients can lead to increased bone loss around dental implants, which is significantly higher in smokers (12).
Previously treated patients who were susceptible to periodontitis have experienced significantly lower success rates for implant therapy and a higher incidence of peri-implantitis after 10 years than patients without a history of periodontitis (90.5% vs. 96.5%) (13). It has been shown that mean alveolar bone loss around dental implants in periodontally susceptible patients is very low as the patients were part of a routine supportive periodontal programme.
It would seem reasonable that all partially dentate patients should receive appropriate periodontal screening and treatment prior to implant placement and are well maintained on a recall schedule for supportive periodontal therapy.
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