|Year : 2019 | Volume
| Issue : 2 | Page : 49-50
Peri-implant bone loss: Unavoidable or can it be slowed?
Editor-in-Chief, Journal of Dental Implants, ProSmile Dental Clinic and Implant Centre, Dr. L. H. Hiranandani Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||13-Jan-2020|
Dr. Sharat Shetty
Editor-in-Chief, Journal of Dental Implants, ProSmile Dental Clinic and Implant Centre, Dr. L. H. Hiranandani Hospital, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Shetty S. Peri-implant bone loss: Unavoidable or can it be slowed?. J Dent Implant 2019;9:49-50
The number of implant placements for missing natural teeth are increasing every year across the globe. This can be attributed to the increasing age of the living population and associated increase in partial and total edentulism. Since implant treatment is a customized and not objective therapy, there are many factors which may lead to uncontrolled complications and failures specially in the hands of unthinking clinicians. Of these, peri-implant bone loss (PIBL) still has been the most common and intriguing failure around osseointegrated implants specially as it is site specific. Though some loss of 1mm in the first year and 0.2 mm per year after that is expected according to old standards, it is essential to reduce and prevent it by knowing the physio-pathogenesis of the bone loss. Since regenerative treatment for rebuilding the lost hard and soft tissues still remains a challenge, it's expected that the clinicians ensure adequate care to avoid and slow the process.
Though implant-abutment-prosthesis attempts to imitate natural tooth, it lacks the similar mode of attachment and inherent defence mechanism and also the site-specific shape. These make functional osseointegrated system susceptible to easy and faster breakdowns like bone loss under unfavourable oral conditions. Hence it is imperative for clinicians to be aware of the possible causes of this dreaded disease and take steps to minimize iatrogenic contributions and identify early signs through regular clinical and radiological appraisals. Bleeding on blunt probing, inflamed to hyperplastic soft tissues, gingival recession, purulent exudates, sinus tracts, increasing probing depths and regressive crestal bone changes on radiographs are some of them. And if left undiagnosed or untreated, it will lead to early crestal bone loss to progressive and/or rapid attachment loss and many times loss of the implant.
Some of important factors contributing to the peri-implant bone loss need attention and they are
- Pre implant assessment: “Following the herd” philosophy has led to immediate placement of implants in all situations without analysing the existent conditions by many clinicians as there are no objective criteria. Even healed sites are managed for their bone volumes only. This haphazard modality has led to unquantified prevalence of the bone loss and less information of post-failure interventions. Pre-existing periodontal and periapical diseases has been the Achilles Heel in early placement of implants and extensive antimicrobial medication have only delayed the real outcome. Other contributing factors are the nature of current systemic disorders, hygiene maintenance and smoking habits. Adequate objective assessment need to be taken for each of them and control measures initiated to reduce the risks of bone loss
- Surgical protocols: Surgical trauma go unnoticed during placement as it depends on the skill and experience and “learning from the past attitude” of the clinician but could be the biggest causative factor of bone loss. Unrespectful elevation of flap tissue, excessive pressure and heat generated during drilling and placement of implants and eventual active closure of incised flaps contribute immensely to the preservation and loss of the labile bone. Sharp drills, low drilling speeds as per the quality of bone, use of cooling irrigants, minimum torque achieved for placement of implants will avoid many thermal and pressure necrosis of bone specially the crestal bone. Temperature of 470 C for 1 minute and 410 C for 7 minutes are well tolerated by bone. Standard operating procedures for implant surgery will prevent these mishaps as prospective investigations are impossible to relate these events and bone loss in a particular case later
- Frequency of exposure of healed bone and disruption of peri-implant soft tissue attachment: Multiple inevitable exposures of the bone after implant placement leads to transient loss of blood supply and ingress of undesirable pathogens and salivary products which may lead to some bone loss. Also soft tissue barrier/seal once achieved cannot be ensured due to surface contamination. Options like the one-time one-transmucosal abutment, one piece implant abutment and transgingival implants can be availed of to ward of this contributing factor
- Microgap between the implant and abutment: Literature is filled with the advantages and limitations of the various types of implant abutment connection but the important aspect is the dimension of microgap under static and functional oral conditions. The change in microgap leads to pumping of the gap microflora in and out which leads to bone loss. Initial torque, screw loosening and components fracture influence the microgap and eventually the crestal bone. Adequate mechanical considerations are necessary to be understood and implemented to manage microgaps and motions under load specially when long span prosthesis are fabricated
- Quality of the soft tissues around the implant-prosthesis: The peri-implant soft tissues consisting of the sulcus depth, epithelial attachment and connective tissues which constitute the health biologic width should be at least 3 mm in length and 1.5 mm in thickness. These tissues are more vulnerable to oral insults when the dimensions reduce and hence periodic appraisals and re-establishing them through innovative grafting strategies are necessary
- Residual cement around cement-retained restorations: Cement-retained prosthesis are the most preferred implant prosthesis as it overcomes most of the inaccuracies of laboratory fabrication. But it leads to accumulation of the residual cement in the implant gingival sulcus which is inferior to the tooth gingival sulcus and progressive peri-implantitis sets in and in turn crestal bone loss. Avoiding deep sulcular margins, use of minimal cements and ensuring adequate cleaning of residual cement with regular recall checks should be undertaken to prevent this iatrogenic failure
- Active fit of the implant prosthesis: Nonpassive fit of the implant prosthesis leads to strain on the screwassembly and on the implant-crestal bone junction leading to slow but progressive bone loss. Precision in clinical and laboratory steps can ensure to passive fit
- Occlusal overloads on implants: The ankylosed implants lack the periodontal ligaments and are deprived of the proprio-mechanoreceptors making them vulnerable to overload. Progressive loading as described by Dr Carl Misch could be employed to ensure adequate remodelling and maturation of bone under less to high occlusal loads over time. Also the two-piece implants have fulcrum of movement at the crestal bone and nonaxial bending forces cause the concentrated forces at the crest of bone leading to early and continuous loss of bone at the crest. Both vertical and horizontal cantilevers could aggravate this slow progression of bone loss. Appropriate choice and designing of the prosthesis with channelizing the occlusal contact loads can minimize the ill-effects of overload
- Parafunctional forces: Continuous, excessive and uncontrolled loads from parafunctional forces are detrimental to osseointegrated junctions and can cause mechanical failures increasing the potential of crestal bone loss. Careful selection of cases for implants and overengineering the suprastructures to withstand these loads are recommended.
Considering the unfortunate events of physiological and pathological crestal bone loss around implants, it's now imperative to evaluate the possible causes contributing to the same in every case during every step of implant planning and execution and take appropriate preventive and corrective interventions to ensure long-term survival as well as success of the implant-prosthesis assembly. Later, periodic assessment allows identification of unexpected causes and address them at the earliest. Else bone loss will remain a sore point in the success of implant practice.
“What is crucial in dealing with loss is not to lose the lesson. That makes you a winner in the most profound sense.”