Formulating a Global Prognosis and Treatment Plan for the Periodontally Compromised Patient: A Reconstructive Vs. an Adaptive Approach

Weiqiang Loke, BDS; Angela M. Coomes, DDS; Adam Eskow, DDS; Matthew Vierra, DDS; Brian L. Mealey, DDS, MS; and Guy Huynh-Ba, DDS, MS

When treating a periodontally compromised patient with restorative needs, clinicians are often faced with a dilemma of retaining teeth with questionable periodontal prognosis or extracting them and providing tooth replacement. Addressing these types of periodontal–restorative treatment planning issues is often predicated on the dental philosophy, background, and training of the practitioner.

Oftentimes, treatment planning is limited by a tooth-by-tooth prognosis rather than a global prognosis; this is due mainly to patient financial constraints and, at times, limited expertise on the part of the practitioner. This limitation may result in compromised esthetics, phonetics, and/or function.

The multidisciplinary global-level philosophy, which the authors call the “reconstructive” treatment approach, is a restoratively driven approach that takes into account tooth-, arch-, and patient-level prognoses. With this approach hierarchal considerations are made in formulating a global prognosis and comprehensive treatment plan. That is, at 1) tooth-level, findings are important for establishing restorative and periodontal stability in patients with limited restorative needs in a relatively intact dental arch; 2) arch-level, findings help establish occlusal stability in patients with high restorative needs in a compromised dental arch; and 3) patient-level, findings are key for establishing stomatognathic stability and longevity of reconstructions in patients with a severely compromised dentition. With the widespread use of dental implants, a global treatment planning approach is necessary to fulfill the long-term restorative needs of the patient.

Problems arise when the reconstructive approach is disregarded, whereby some periodontally questionable teeth are maintained and others are extracted and replaced with dental implant-supported restorations without appropriate regard for the long-term potential problems that may occur if more teeth eventually require extraction. If further tooth extraction and replacement with implants is needed and is done on a tooth-by-tooth basis, discrepancies in the anterior-posterior and apico-coronal implant locations, inappropriate prescription in the number of implants, use of multiple implant systems, compromised occlusal schemes, and questionable prognosis of the remaining dentition may complicate future treatment planning.

But, when the focus is mainly set on a tooth-level, arresting the breakdown of the periodontium of the individual teeth and associated restorations becomes the primary goal. This well-documented treatment approach has successfully demonstrated that the periodontally compromised dentition can be maintained over the long term with appropriate patient control of local and systemic factors in conjunction with regular professional evaluation and maintenance. This approach offers the patient much therapeutic value and would less likely complicate restorative treatment planning for patients who only require conventional non-implant–based restorative therapy. The authors refer to this as the “adaptive” treatment approach, as it generally adapts restorative care to the patient’s existing teeth and arch form.

Case Presentation

A patient scenario is presented that offers thought-provoking treatment considerations. Treatment could easily follow either the adaptive or reconstructive approach to satisfy the patient’s desires and result in the best long-term solution.

The patient presented at the University of Bern in the Department of Periodontology and Fixed Prosthodontics in May 2003. Upon comprehensive initial examination of the 58-year-old Caucasian male, a diagnosis of generalized severe chronic periodontitis was assigned (Figure 1 and Figure 2). The patient’s medical history was non-contributory. The patient reported smoking a pack of cigarettes per day for the past 30 years. Oral hygiene was extremely poor; the patient had neglected his oral health for many years.

Teeth Nos. 1 through 3, 14 through 16, and 25 were missing. Probing depths ranged from 2 mm to 10 mm, while attachment levels ranged from 3 mm to 12 mm, with significant bleeding on probing. Class 2 Miller’s mobility¹ was noted for teeth Nos. 18, 23, 24, and 26. All teeth tested vital to cold, and Grade 3 Glickman furcation involvement² was noted on teeth Nos. 17 through 19 and 30 through 32. An assessment of the patient’s systemic health, age, behavioral/psychological status, socioeconomic status, and esthetic and functional goals was completed and taken into account in the prescribed treatment plan.

Clinical Approaches

This patient scenario presents a common treatment planning dilemma. In cases of generalized severe chronic periodontal destruction, differences in treatment methodology may be highlighted through two somewhat antagonistic approaches: reconstructive versus adaptive.

An adaptive approach is characterized by conservative retention of teeth deemed to have a good-to-questionable prognosis and utilizing limited restorative therapy that may consist of removable and/or fixed conventional/implant-based restorative prostheses. The reconstructive approach, on the other hand, is typically characterized by a more interceptive and prosthetically driven therapy whereby questionable teeth are extracted early to make way for implant-based restorative prostheses. The differences between the adaptive and reconstructive approaches are summarized in Table 1.

On one side, the reconstructive approach calls for a more occlusally and biomechanically stable therapeutic endpoint through prosthetically driven therapies, including total odontectomy with alveoloplasty for prosthetic rehabilitation. On the other side, an adaptive and more conservative approach aims at arresting disease progression through traditional periodontal surgical intervention and maintenance of the existing dentition. These two treatment approaches illustrate different paths to common goals: oral health and occlusal stability. The proven clinical success of periodontal therapy and maintenance supports the adaptive treatment approach that is often overlooked by practitioners seeking to establish an arch-level implant-restorative solution at the cost of salvageable teeth, which, at best, may achieve similar long-term outcomes. There are merits to both arguments, as will be discussed in the following paragraphs. It should be noted that, depending on the complexity of a case, both treatment approaches may require a multidisciplinary team strategy involving different specialties (eg, periodontics, orthodontics, endodontics, and oral surgery) to ensure a comprehensive assessment of the case prior to treatment planning.

An adaptive approach to treatment consists of comprehensive periodontal therapy, extraction of hopeless teeth, followed by restorative therapy. In the present case, based on the clinical examination (including patient’s full-mouth periodontal chart), radiographs, and clinical photographs (Figure 1 and Figure 2) obtained, it was evident that teeth Nos. 17 through 19 and 30 through 32 had a hopeless prognosis due to severe bone loss, thorough furcation involvements, and dento-alveolar extrusion. All other teeth were considered to have a fair-to-poor prognosis with periodontal therapy. The restorative options given to the patient included extraction of all remaining maxillary teeth and reconstruction with an implant-retained or implant-supported fixed or removable prosthesis. Instead, the patient elected to retain all questionable teeth in both arches and extraction of his hopeless teeth, choosing to maintain as many of his natural teeth as possible; he elected not to have any replacement for his posterior teeth. This restorative plan was based on the shortened dental arch philosophy.³ Periodontal therapy for the patient included four quadrants of scaling and root planing, extraction of teeth Nos. 17 through 19 and 30 through 32 due to hopeless periodontal prognosis. Periodontal re-evaluation at 8 weeks showed dramatic improvements in oral hygiene efforts, with minimal gingival erythema and bleeding on probing only at sites with deeper probing depths. Periodontal surgery followed, which included open-flap debridement with limited osteoplasty and regeneration using the principles of guided tissue regeneration at site No. 10.

The patient was then seen for periodontal maintenance at 3-month intervals, which demonstrated maintainable pockets of 3 mm to 4 mm, although mobility of Nos. 24 and 26 increased. Upon re-evaluation at the maintenance phase, a second-phase restorative treatment plan was accepted by the patient, which included extractions of Nos. 24 and 26 and implant placement at these corresponding sites. Restorative treatment ensued and the patient eventually received implant-supported fixed dental prostheses to replace teeth Nos. 23 through 26 (Figure 3).

Support for this approach in treating the patient is provided by research showing that periodontal treatment of a periodontally compromised dentition has relatively predictable outcomes overall. Classic studies have shown that 62% to 83% of teeth are well-maintained with minimal tooth loss over 15 to 22 years in chronic periodontitis patients who receive periodontal treatment and maintenance every 4 to 6 months.^4-6 Each of these long-term studies demonstrates that a small number of patients exhibit progression of periodontal destruction despite optimal therapy and maintenance (4% extreme downhill patients who lost 10 to 23 teeth, 13% downhill patients who lost 4 to 9 teeth). It is this risk for progressive disease that may cause clinicians to re-evaluate the traditional approach to managing such patients, especially when dental implants become part of the restorative treatment plan.

An alternative approach to treating the same patient who desires fixed restorative solutions or implant-retained/supported therapy would be to initiate the treatment planning process using a reconstructive approach that prioritizes the most efficient and effective restorative solutions for the patient as the primary consideration. This approach takes into account the prognoses at each of the three aforementioned levels (ie, tooth-level, arch-level, and patient-level). These tooth-level (ie, endodontics, periodontics, prosthodontics, orthodontics) and arch-level (ie, periodontics-prosthodontics, oral surgery-orthodontics) prognostic assessments may include the presenting tooth anatomy, tooth structure, periodontium, pulpal system, arch form, arch relation, space distribution, alignment of teeth, and status of existing restorations or defects. These assessments should then be correlated with patient-level assessments, largely centered on the patient’s biologic, biomechanical, social, environmental, esthetic, financial, and psychological risk profiles.

Before arriving at a decision whether to extract or retain a tooth or teeth, the clinician should develop a global prognosis of the patient, taking into account the projected future needs and risks that may affect long-term treatment outcomes. Allocating an accurate prognosis for each individual tooth and for the entire dentition is a difficult task, and research demonstrates that prognostication is an imprecise process that often leads to erroneous conclusions.^7-9 However, when restorative therapy includes implants, it is paramount that the clinician bases prognostic decisions on patient-level risk profiles (biologic, esthetic, biomechanical, caries, etc.) that may directly impact the future of the patient’s final restorative scheme. Implants placed in one position today to replace a single tooth may end up being in a completely incorrect location in the future should further tooth loss occur and a more extensive restorative plan be required (Figure 4). The undesirable results of a tooth-by-tooth replacement strategy, including inappropriate number and poor distribution of implants, can be avoided if patient-level and arch-level considerations override tooth-level considerations.

Hence, the reconstructive treatment approach is built upon the pertinent regional tooth-related and arch-related issues in restoring the patient back to health, rather than being focused on the tooth-level prognoses (Table 1). The overriding patient-level considerations and restorative needs, being above those of arch-level and tooth-level assessments, drives the clinician to consider and anticipate alternative restorative solutions needed for the patient (reconstructive therapy versus adaptive therapy). This treatment planning approach satisfies the rationalization for tooth extraction or retention while at the same time affording critical biomechanical considerations, such as optimal implant distribution (anterior-posterior spread, minimizing distal cantilever) and positioning, to be factored into treatment planning for the eventual implant-based restorative needs of patients with a severe periodontally compromised dentition. The reconstructive approach would result in total odontectomy of the maxillary arch with retention of the posterior mandibular teeth and mandibular canines. A full-arch, fixed, implant-retained maxillary hybrid prosthesis combined with an implant-retained mandibular fixed dental prosthesis for Nos. 23 through 26 would restore the patient’s esthetics, health, and function.

The approach utilizing a full-arch implant-supported fixed dental prosthesis (Figure 5 through Figure 7) is well-evidenced in the literature. Malo et al,^10,11 who has published a series of articles on maxillary reconstructions based on an all-on-4 concept, has demonstrated that this can be a successful treatment approach. The cumulative 10-year success rates for such prostheses in the edentulous mandible were 93.8% and 94.8% for patient-related and implant-related success, respectively.¹⁰ Interestingly, the use of this treatment modality in edentulous patients with a previous history of periodontal disease yielded a decreased 5-year success rate to 91%.¹¹ Therefore, if extractions are due to previous periodontal disease, the clinician must consider that the prognosis of implant-supported fixed dental prostheses does not compare as favorably.

Full-arch implant-retained prostheses utilizing more than four implants have similar prosthesis success and survival rates. A recent systematic review and meta-analysis reported the 5-year and 10-year survival rates and associated complications of implant-retained prostheses in partial or totally edentulous patients.¹² For full-arch implant-retained prostheses in the maxilla with four to six implants, the survival rate was 97.5% at 5 years, while the 10-year survival rate was 95%. A restored mandibular arch reported similar survival rates (98% and 95.9% at 5 and 10 years, respectively).¹² Furthermore, an 8-year prospective study following subjects with full-arch implant-retained prostheses in the maxilla supported by six implants reported an implant survival rate of 99% and a prosthesis survival rate of 100%.¹³

Discussion

The aforementioned clinical approaches are common treatment considerations for a patient with generalized severe chronic periodontitis. One approach—the adaptive approach—utilizes conventional periodontal, endodontic, and restorative therapy while maintaining as many natural teeth as possible. The other approach—reconstructive—focuses particularly on the prognosis of the teeth and arch over the long term and uses primarily implant-based fixed restorations. Philosophically, the two approaches share a sincere attempt to prevent breakdown of the stomatognathic system. One focuses on the preservation of teeth and stability of periodontium (bone, periodontal ligament, and cementum) while the other focuses on establishing long-term stability of the occlusion. Both are likely to enable the optimal function of the stomatognathic system comprising the temporomandibular joints, neuromusculature, teeth, and periodontium, with the major difference between approaches being the restorative complications that may occur over time. With the adaptive approach, further periodontal destruction and loss of teeth in the future may result in significant restorative needs and may render existing implant-borne prosthesis useless due to inappropriate platform location or poor angulation (Figure 4). Implants placed when teeth were still present may no longer be in the correct location for more extensive prostheses, and, in some cases, previously placed implants may have to be removed in order to allow for proper reconstruction of the dentition. 

The adaptive and reconstructive approaches presented for this patient each offers distinct advantages and disadvantages. Maintaining natural teeth, as would be the case with the adaptive treatment approach, has potential advantages over extraction. Esthetics of natural teeth is more predictable, while prosthetic teeth are subject to greater patient criticism. Extraction of multiple teeth at once may also have psychological implications, with many patients unwilling to accept this course of treatment. Finally, avoiding implant placement will prevent the possibility of peri-implant bone loss and subsequent treatment for potential peri-implant disease.

Disadvantages also exist when considering long-term maintenance of questionable teeth. Keeping teeth with advanced attachment loss and pathologic tooth migration may not be esthetically acceptable to the patient. In patients with a history of advanced periodontal disease, maintenance procedures on a reduced periodontium may slow the progression of bone loss. However, recurrence of periodontitis is possible in the future and, as a consequence of increased bone loss, unpredictable tooth loss pattern and abutment tooth loss, increased costs for prosthetic conversions, increased in-office visits, and eventual implant placement may be more complicated.

Implant placement in periodontally compromised patients has been evaluated in the literature. Treating and maintaining periodontally diseased teeth of questionable prognosis has to be put in perspective with the increased risk for future peri-implantitis and possible implant failure, which could jeopardize prosthetic success. Emerging periodontal literature strongly associates an increased risk of peri-implantitis in patients with a history of periodontal disease.^14,15 In a systematic review by Heitz-Mayfield et al, an implant survival rate of > 90% was reported in patients with a previous history of periodontitis.¹⁴ While this figure seems encouraging, the corresponding odds ratio for developing peri-implantitis in those patients with a previous history of periodontitis compared to a healthy population was 3.1 to 4.7.¹⁴

Similar findings were described in a prospective cohort study following periodontally healthy and periodontally compromised patients with implants over 10 years.¹⁵ More peri-implant bone loss and lower implant survival rates were reported in periodontally compromised patients, especially in those who were not as compliant with periodontal maintenance.

In most cases, a few years are needed following implant placement to detect peri-implant bone loss and peri-implant disease. A study by Levin et al demonstrated that an increased risk for peri-implantitis in patients with a history of periodontitis when compared to those without a history of periodontitis is often not evident until approximately 5 years after implant placement.¹⁶ This increase in risk of peri-implant disease over time is important when considering the retention of periodontally compromised teeth versus extraction of the remaining teeth and placement of implant-supported restorations. Short-term success rates for the latter type of therapy may not accurately reflect long-term prognosis for the implants in these patients. Levin et al suggest that the limited evidence for an increase in implant failure or complication rates over time in patients with a previous history of periodontitis is due to the fact that very few studies have examined such patients over long enough time periods, ie, decades.¹⁶ Is it possible that patients who have their periodontally compromised dentition removed and reconstructed with implants rather than have their natural dentition retained, treated, and maintained periodontally may be at high risk of one day developing a similar disease condition affecting their implants and associated restorations? There is currently little evidence on which to base an answer to this question.

In a recent review by Donos, treatment options for periodontally compromised patients were considered.¹⁷ The review favored the long-term maintenance of periodontally compromised teeth over replacement with dental implants. Tooth-borne prostheses were shown to have similar functional capacity and survival rate compared to implant-retained restorations in a patient with periodontal disease. Also, well-maintained periodontally compromised teeth had a similar 10-year survival rate as implants placed in patients with a history of periodontal disease. Not only is there evidence for increased risk of peri-implantitis in previously periodontally diseased patients, but also evidence that treatment of peri-implantitis is unpredictable at this time.¹⁷ Various therapeutic modalities for the treatment of peri-implantitis lesions have been suggested.^18-21 Treatment outcomes were encouraging but long-term evidence of stability is still lacking.

The reconstructive approach has its own advantages and disadvantages, too. Its primary disadvantage is that some teeth that actually have a relatively good prognosis on a tooth-by-tooth basis may be prematurely removed. Conversely, a major advantage of the reconstructive approach is the ability to plan the implant-based prosthesis from a foundation that has no remaining teeth. Implants can be placed in the ideal positions to support the prosthesis, with appropriate anterior-posterior spread and ideal implant platform locations in the apico-occlusal dimension. If alveolar ridge reduction is needed to provide appropriate restorative space for the prosthesis, alveoloplasty can be done without regard to its effect on any remaining natural teeth. This allows the implant platforms to be placed at a position that facilitates the space requirements of the final prosthesis. It has been reported in the literature that patients restored with conventional therapy on natural teeth are at increased risks for biological and technical complications.²² In a review article by Goodacre et al, the failure rates for conventional fixed dental prostheses were 26%; conventional single crowns, 11%; posts and cores, 10%; and all-ceramic crowns, 8%.²² On the other hand, implant failures for the various implant-based restorations were reportedly lower, with failure rates of 10% for maxillary fixed complete dentures and 3% for mandibular fixed complete dentures.²²

Another advantage for reconstructive treatment consists of psychological and functional improvements for the patient. Implant therapy has been shown to have a positive effect on the oral health-related quality of life (OHQOL).^23,24 Studies comparing implant-based therapy with tooth-borne removable dental prostheses in partially edentulous patients showed higher OHQOL scores with implant-supported fixed partial dentures compared to tooth-borne removable prostheses.^23,24 Finally, perhaps the most perceptible advantage of the reconstructive approach would be that of better esthetics and the negation of common issues of black triangles and tooth sensitivity following surgical periodontal therapy. This advantage, however, needs to be weighed against the high probability of prosthetic complications that may continuously arise during the life-cycle of the prosthesis, where biologic and technical complications are known to occur due to fatigue loading and stress, the most common being bone loss, soft-tissue hyperplasia, implant screw fractures, and chipping or fracture of prosthetic material.²⁵

Conclusion

With all of the previously discussed factors taken into account, the clinician and patient must make a finalized informed treatment decision. The patient must be told of the necessity for long-term maintenance of the dentition following comprehensive periodontal therapy or following rehabilitation with a full-arch implant-retained hybrid restoration or other implant-borne restorations. In either case, the patient must be motivated to continue improving his or her oral health. As general dentists and specialists move further toward dental implant treatment as essential to dental therapy, it is critical to remain mindful of the need for maintenance of implants as well as teeth. All too often, the patient’s periodontal problem is considered “solved” with implants, disregarding the similar problem that dental implants present to patients with poor oral hygiene, sporadic dental care, and a history of inflammatory disease around the teeth.

It is also important to discuss with the patient the 10-year outlook of the dentition in order for the patient to make an informed decision regarding the course of restorative treatment. Dental professionals know from long-term periodontal maintenance studies that it is possible to adequately maintain teeth, but they are also aware of the consequences of peri-implantitis and the limitations of treatment for peri-implantitis. The decision to extract a periodontally compromised patient’s entire dentition and subsequently replace the teeth with implants and a full-arch implant-retained prosthesis must be carefully thought out, and the long-term concerns need to be reviewed with the patient. A close working relationship with a restorative dentist to help direct treatment is critical in order to provide the best multidisciplinary care for a patient with a compromised dentition.

ABOUT THE AUTHORS

Weiqiang Loke, BDS
Department of Periodontics, University of Texas Health Science Center at San Antonio Dental School, San Antonio, Texas

Angela M. Coomes, DDS
Department of Periodontics, University of Texas Health Science Center at San Antonio Dental School, San Antonio, Texas

Adam Eskow, DDS
Department of Periodontics, University of Texas Health Science Center at San Antonio Dental School, San Antonio, Texas

Matthew Vierra, DDS
Department of Periodontics, University of Texas Health Science Center at San Antonio Dental School, San Antonio, Texas

Brian L. Mealey, DDS, MS
Professor and Graduate Program Director, Department of Periodontics, University of Texas Health Science Center at San Antonio Dental School, San Antonio, Texas

Guy Huynh-Ba, DDS, MS
Associate Professor, Department of Periodontics, University of Texas Health Science Center at San Antonio Dental School, San Antonio, Texas

REFERENCES

1. Miller SC. Textbook of Periodontia. 1st ed. Philadelphia, PA: P. Blakiston’s Son; 1938.

2. Glickman I. Clinical Periodontology. 1st ed. Philadelphia, PA: WB Saunders Co.; 1953.

3. Käyser AF. Shortened dental arches and oral function. J Oral Rehabil. 1981;8(5):457-462.

4. Hirschfeld L, Wasserman B. A long-term survey of tooth loss in 600 treated periodontal patients. J Periodontol. 1978;49(5):225-237.

5. McFall WT Jr. Tooth loss in 100 treated patients with periodontal disease. A long-term study. J Periodontol. 1982;53(9):539-549.

6. Goldman MJ, Ross IF, Goteiner D. Effect of periodontal therapy on patients maintained for 15 years or longer. A retrospective study. J Periodontol. 1986;57(6):347-353.

7. McGuire MK. Prognosis versus actual outcome: a long-term survey of 100 treated periodontal patients under maintenance care. J Periodontol. 1991;62(1):51-58.

8. McGuire MK, Nunn ME. Prognosis versus actual outcome. II. The effectiveness of clinical parameters in developing an accurate diagnosis. J Periodontol. 1996;67(7):658-665.

9. McGuire MK, Nunn ME. Prognosis versus actual outcome. III. The effectiveness of clinical parameters in accurately predicting tooth survival. J Periodontol. 1996;67(7):666-674.

10. Malo P, de Araujo Nobre M, Lopes A, et al. A longitudinal study of the survival of All-on-4 implants in the mandible with up to 10 years of follow-up. J Am Dent Assoc. 2011;142(3):310-320.

11. Malo P, de Araujo Nobre M, Rangert B. Implants placed in immediate function in periodontally compromised sites: A five-year retrospective and one-year prospective study. J Prosthet Dent. 2007;97(6 suppl):S86-S95.

12. Heydecke G, Zwahlen M, Nicol A, et al. What is the optimal number of implants for fixed reconstructions: a systematic review. Clin Oral Implants Res. 2012;23(suppl 6):217-228.

13. Mertens C, Steveling HG. Implant-supported fixed prostheses in the edentulous maxilla: 8 year prospective results. Clin Oral Implants Res. 2011;22(5):464-472.

14. Heitz-Matfield LJ, Huynh-Ba G. History of treated periodontitis and smoking as risks for implant therapy. Int J Oral Maxillofac Implants. 2009;24(suppl):39-68.

15. Roccuzzo M, De Angelis N, Bonino L, Aglietta M. Ten-year results of a three arms prospective cohort study on implants in periodontally compromised patients. Part I: implant loss and radiographic bone loss. Clin Oral Implants Res. 2010;21(5):490-496.

16. Levin L, Ofec R, Grossman Y, Anner R. Periodontal disease as a risk for dental implant failure over time: a long-term historical cohort study. J Clin Periodontol. 2011;38(8):732-737.

17. Donos N, Laurell L, Mardas N. Hierarchical decisions on teeth vs. implants in the periodontitis-susceptible patient: the modern dilemma. Periodontol 2000. 2012;59(1):89-110.

18. Renvert S, Samuelsson E, Lindahl C, Persson GR. Mechanical non-surgical treatment of peri-implantitis: A double-blind randomized longitudinal clinical study. I: Clinical results. J Clin Periodontol. 2009;36:604-609.

19. Heitz-Mayfield LJ, Salvi GE, Botticelli D, et al. Anti-infective treatment of peri-implant mucositis: a randomized controlled clinical trial. Clin Oral Implants Res. 2011;22(3):237-241.

20. Froum SJ, Froum SH, Rosen PS. Successful management of peri-implantitis with a regenerative approach: A consecutive series of 51 treated implants with 3-to 7.5-year follow-up. Int J Periodontics Restorative Dent. 2012;32(1):11-20.

21. Serino G, Turri A. Outcome of surgical treatment of peri-implantitis: results from a 2-year prospective clinical study in humans. Clin Oral Implants Res. 2011;22(11):1214-1220.

22. Goodacre CJ, Bernal G, Rungcharassaeng K, Kan JY. Clinical complications with implants and implant prostheses. J Prosthet Dent. 2003;90(2):121-132.

23. Nickenig HJ, Wichmann M, Andreas SK, Eitner S. Oral health-related quality of life in partially edentulous patients: assessments before and after implant therapy. J Craniomaxillofac Surg. 2008;36(8):477-480.

24. Furuyama C, Takaba M, Inukai M, et al. Oral health-related quality of life in patients treated by implant-supported fixed dentures and removable partial dentures. Clin Oral Implants Res. 2012;23(8):958-962.

25. Papaspyridakos P, Chen CJ, Chuang SK, et al. A systematic review of biologic and technical complications with fixed implant rehabilitations for edentulous patients. Int J Oral Maxillofac Implants. 2012;27(1):102-110.