Implant Therapy: Clinical Approaches and Evidence of Success, Second Edition

By Myron Nevins and Hom-Lay Wang

Since the publication of the first edition of this book 20 years ago, the landscape of implant dentistry has changed dramatically. Both the industry and patient demand have expanded exponentially, leaving the clinician with many decisions to make (and often as many questions to ask) regarding patient selection, surgical timing and techniques, implant types, and restorative approaches. This volume brings together the knowledge of the foremost leaders in implant dentistry, covering all aspects of the treatment process, from decision-making and treatment planning through imaging, surgical techniques, bone and soft tissue augmentation, multidisciplinary approaches, loading protocols, and finally strategies for preventing and treating complications and peri-implantitis as well as providing effective implant maintenance therapy. Filled with expert knowledge based on decades of research and clinical experience as well as abundant illustrations and clinical case presentations, this book is an indispensable resource for clinicians seeking to provide implant treatment at the highest standard of care.

• Language: English
• Publisher: Quintessence Publishing Co, Inc
• Release date: Jan 13, 2020
• ISBN: 9781647240059

Book preview

1

MYRON NEVINS • RICHARD I. HERMAN • YOSHIHIRO ONO

A Clinical Decision: Save the Tooth or Place an Implant?

Treatment Planning Considerations

Treating Periodontally Compromised Teeth

The Endodontic Treatment Option

Treating Patients with Sound Periodontium and a Localized Problem

Periodontal Regeneration

Decision Making for Saving the Natural Dentition

Esthetic Considerations

The contemporary hallmark of a superior clinician is the ability to select therapies that are predictable and have long-lasting results. The question of whether to save a tooth or replace it with a dental implant is multifaceted, and the assessment requires a multidisciplinary approach to dental care. Giannobile and Lang have reported a trend over the past two decades toward a reduced emphasis in clinical practice to save compromised teeth. 1 They suggest that clinicians should revisit the long and successful history of tooth maintenance, preserving the natural dentition without the rush to extract teeth and replace them with implants. Dental practitioners do a disservice to their patients and themselves when they fail to carefully weigh the advantages and disadvantages of such options in providing optimal oral health care delivery to patients.

TREATMENT PLANNING CONSIDERATIONS

Decisions made in treatment planning often determine the value of the result for the patient. Contemporary dentistry has benefited from the predictability of osseointegration,2–10 periodontal regeneration,11–29 successful endodontics,30 and prosthodontics, four compelling areas in which the clinician must be knowledgeable in order to make an informed decision regarding when to save the tooth or place an implant.

Nearly every patient asks the same questions during consultations. They are the following:

•How much discomfort will I endure?

•How many visits will be required?

•What will be the total treatment time?

•How will this affect my appearance?

•What is the financial commitment?

•What is the expected longevity of the treatment outcome?

There is minimal information available in evidence-based dentistry to assist in making many clinical decisions because of the number of variables that challenge the recruitment of populations for randomized controlled trials. As a result, when considering the prospect of replacing a maxillary first premolar with two roots, for example, clinicians eventually resort to their own clinical experience or case report publications. Considerations that must be made include the following:

•What is the distance from the apex of the tooth to an anatomical obstacle, and will it be necessary to augment the bone in the floor of the sinus ( Figs 1-1a and 1-1b )?

Fig 1-1 (a and b) It is impossible to have just one protocol for a maxillary first premolar. There is ample bone on the left side to accept an osseointegrated implant; however, if the maxillary first premolar were extracted on the right side it probably would be necessary to augment bone to receive an implant. (c and d) Cadaver material demonstrating the difference in bone levels between a patient with a healthy dentition and a patient who is severely compromised periodontally. The prime dictating factor relates to the length of the clinical root rather than the length of the anatomical root.

•What is the position of the roots of the tooth relative to each other and to the neighboring teeth?

•Is the tooth vital, and how intact is the tooth structure and the occlusal level of bone ( Figs 1-1c and 1-1d )?

•What type of lip line and dental display does the patient have, and how will it affect the esthetics?

•Could the tooth be treated endodontically? (A 2009 report by Morris et al 31 concluded that implants require more postoperative treatment than endodontically treated teeth, possibly a result of contemporary advancements. In addition, many endodontic complications, with the exception of fractured teeth, are resolvable.)

Implant patients fall into two general categories. The first includes individuals with teeth that are congenitally missing or damaged by trauma or root resorption (Fig 1-2). The second group has demonstrated susceptibility to inflammation that is evidenced by radiographic bone loss (Fig 1-3). Those in the first category require only tooth structure correction or replacement, whereas the second group presents the additional challenge of preventing or minimizing recurrent inflammation. The primary factor dictating decision making becomes the length of the clinical root, ie, that portion of the tooth that resides in the alveolar process (see Figs 1-1c and 1-1d). With a susceptible patient, it is advisable to eliminate the periodontal disease and provide a carefully constructed periodic maintenance program to reduce the risk of active inflammatory disease.32 The therapeutic result has to provide an environment that the patient and dental hygienist can maintain (see Fig 1-3).

Fig 1-2 (a to c) A young woman with root resorption on the distal surface of the right central incisor. An esthetic dental display is very important to the patient. (d to f) The clinical and radiographic postoperative result after replacing the damaged tooth with an osseointegrated implant.

Fig 1-3 (a) The patient presented for a periodontal regeneration procedure. The radiographic examination demonstrated intrabony defects that were not contained, therefore eliminating the possibility of periodontal regeneration. The two premolars were removed, the alveolar process underwent reconstruction, and two dental implants were placed. (b) A 3-year posttreatment radiograph illustrates significant recovery and no evidence of bone loss. (c) The bone-implant contact remains steady after 14 years. This demonstrates that patients susceptible to disease can accept osseointegrated implants successfully.

It is of paramount importance to recognize at the outset that it is possible, and in some instances preferable, to use the time-honored therapeutic approaches of conventional restorative dentistry. Although there is a lack of controlled studies in the discipline of periodontal prostheses, there is a paucity of significant randomized controlled human studies to support the clinical application of many periodontal and prosthetic approaches. There is, however, overwhelmingly positive clinical evidence gathered through the observation of treated patients to be considered. Periodontally compromised patients with mobile, drifting, or missing teeth have been successfully rehabilitated with or without implants (Figs 1-3 to 1-5). Such patients require a treatment plan that provides predictability over an extended time frame.

Fig 1-4 (a) The patient presented with generalized advanced periodontitis. (b) A radiographic survey 1 year after the placement of many dental implants. Red circles indicate post and core risk. (c and d) Radiographic and clinical observation after 7 years. The maxillary left canine suffered a vertical root fracture and was replaced by a third 18-mm implant. The molar was removed and replaced with a cantilever. (e and f) Clinical presentation after 17 years. (g) A radiographic survey after 25 years. Once again, this demonstrates that people susceptible to periodontal disease can be treated successfully with osseointegrated implants.

Fig 1-5 (a and b) Before and after radiographic surveys of a patient clearly susceptible to inflammatory periodontal disease. (c) A 13-year radiographic survey demonstrating the replacement of the maxillary first molars with fixed restorative dentistry. (d) The radiographic survey after 34 years. Red circles indicate loss of supporting bone. (e) A 50-year posttreatment radiographic survey. Treatment has been provided in an incremental fashion as additional areas required treatment.

In patients with few missing teeth or those with obvious periodontal disease, total extraction of the dentition and replacement with implants is frequently unnecessary (Figs 1-6 and 1-7). There are many examples of positive long-term results with maintenance of the dentition, while at the same time there are increasing complications with implants. It is unfortunate that the dental profession frequently is unaware of the positive results of traditional periodontal, endodontic, and prosthetic care.10,33,34

Fig 1-6 This patient first presented in the year 1962 (a). Finances prevented the extraction of the maxillary first premolars and the construction of fixed partial dentures. These radiographs taken at 12 (b), 21 (c), and 37 (d) years show that the first premolars remained in the patient’s mouth for 37 years with no corrective therapy. The recall interval was 3 months, and the patient continued to be punctual until her death. This is an example that must be looked at as an outlier.

Fig 1-7 (a) This patient presented with significant loss of the periodontium in 1968. Her chief complaint was that the teeth were too mobile to masticate food. The initial therapy included nonsurgical treatment and splinting of the teeth. After this was successful, bone was harvested from the edentulous maxilla to regain periodontium where possible. (b) The patient retained all 10 teeth for 10 years. (c) Radiographs at 20 years. Her restorative dentist restored all of the teeth with fixed crowns in 1997. (d) The 2016 radiographic survey demonstrates 9 of the 10 teeth still functioning. The original endodontic treatment for the left central incisor was questionable and became problematic (green arrow).

TREATING PERIODONTALLY COMPROMISED TEETH

Favorable results can be accomplished when implants are placed in patients with a chronic history of periodontal disease. There are many publications that have demonstrated long-term healthy and functional implants in place after the loss of periodontally compromised teeth.9,10,35–39 It has been recognized that two very important factors are the elimination of periodontal disease before implants are placed and the availability of oral hygiene programs.32,40

Implants have provided an opportunity to greatly reduce the necessity for periodontal heroics by taking advantage of osseointegration. However, there is overwhelming evidence that periodontally compromised teeth can survive indefinitely.41–43 Esthetics and masticatory function may become compromised over time for some patients, but this is not usually the case. Osseointegrated implants have been one of the most significant improvements of the 20th century, and when appropriate, provide solutions heretofore unavailable. It is important that the dentist weigh the success of saving a tooth using the capabilities of contemporary periodontal regeneration and/or endodontics against the success of an implant. This presents a significant conflict for the knowledgeable dentist, while practitioners with minimal knowledge of the success of periodontics and endodontics generally find it easier to place an implant. The most important question for the dentist is, What would I do if this problem were in the mouth of a friend or loved one?

Before peri-implantitis was encountered, it was believed that implant success would exceed 90%.2–4,11 Several studies have demonstrated the error of thinking that implants always have a better long-term prognosis than teeth with treatable problems.44 Recent studies show that peri-implantitis and mucositis are frequent complications that challenge the future health of an implant.45,46 Therefore, the decision has to be carefully considered before treatable teeth are removed.

Conversely, there are routine treatment plan objectives for which tooth replacement with implants offers a better prognosis. When teeth are mobile because of significant loss of bone, esthetics may be greatly affected, even in a posterior quadrant. If there is horizontal bone loss beyond 50%, the bone level of adjacent teeth will contribute to vertical bone reconstruction, allowing implant placement to be favorable and providing a more acceptable result than resorting to pocket elimination surgery (see Fig 1-3).

THE ENDODONTIC TREATMENT OPTION

Recent literature demonstrates that endodontics and single-tooth implant therapy have similar success rates. Hannahan and Eleazer found that 95% to 97% of teeth with treated root canals were retained after a period of 8 years compared with implant retention rates of 85% to 90% over a similar time span.47 Postoperative intervention, an indication of treatment failure, was noted for 12.4% of implants compared with 1.3% of endodontically treated teeth. A more recent report studied the 10-year success rate of 1,175 endodontically treated teeth.48 The life-table analysis demonstrated that 93% of the teeth survived 10 years after endodontic treatment. However, it is critical to determine the criteria for success used when discussing implants.

Endodontic procedures are best performed under the surgical operating microscope, as it enhances the clinician’s ability to locate and navigate canals.49 It has been shown that with the microscope the ability to locate second mesiobuccal canals has increased from 53% to 93%.50,51 The success rates of periapical surgery have also demonstrated significant improvement (Figs 1-8 to 1-10). In such procedures, it is imperative to prepare the crypt and the canals as well as place the retroseal.52

Fig 1-8 (a) A preoperative apical pathosis accompanied by lateral periodontal breakdown. (b) After treatment with bioceramic sealer and a lateral canal adjacent to the cervical periodontal bone loss. The red arrow designates loss of bone on the mesial surface of the molar. (c) Postoperative radiograph showing healing periapically and periodontally. The green line indicates the lateral canal. The red arrow designates loss of bone on the mesial surface of the molar. (c) Postoperative radiograph showing healing periapically and periodontally. The green line indicates the lateral canal. The red arrow shows the regeneration of bone adjacent to the root.

Fig 1-9 (a) Preoperative radiograph of a nonvital mandibular molar with periapical pathosis. (b) Following obturation with biocompatible bioceramics. (c) Healed periapical pathosis at 6 months.

Fig 1-10 (a) Preoperative periapical lesion with a post present in the distal canal. (b) Following microsurgery using compatible bioceramics with an ultrasonic retrograde preparation. (c) Complete resolution of periapical pathosis at 6-month recall.

The introduction of nickel titanium instrumentation allows the clinician to shape the canal, which increases the ability of the irrigation protocol to clean the complex anatomy of the root canal system. In addition, new advancements in material science related to obturation have developed. It is now possible to have a biocompatible sealer that bonds to dentin, as well as gutta-percha, which provides a fluid yet impermeable and tight seal.52

However, this should not be perceived as a competition between endodontics and implant treatment; rather, they should complement each other. On the basis of survival rates, it appears more than 95% of single-tooth implants and teeth that have undergone endodontic treatment remain functional over time50 (see Figs 1-8 to 1-10).

TREATING PATIENTS WITH SOUND PERIODONTIUM AND A LOCALIZED PROBLEM

There are frequently situations in which a tooth in the esthetic region can be saved, but the patient would benefit from its replacement with an implant. When both conventional and surgical endodontics have failed, extraction and site reconstruction allow the clinician to place an implant or a three-unit fixed partial denture. It is then possible to consider the length of the restoration and predict the likelihood of interproximal black triangles. It is also an advantage to replace one tooth without altering adjacent teeth (Fig 1-11).

Fig 1-11 (a and b) A fistula (yellow arrows) remains at the maxillary right central incisor root after apical surgery. (c) The tooth was extracted, and the area was grafted to repair the osseous damage. (d) Six months later, a dental implant was placed. (e) The result satisfied the patient. (f) There is scar evidence of the previous endodontic surgery.

PERIODONTAL REGENERATION

Not every tooth with reduced alveolar support is a candidate for extraction, especially if it would result in loss of continuity of the natural dental arch.53–56 These defects may be identified in patients with either a localized problem or advanced generalized periodontal disease. Variables such as age, medical history, esthetic expectations, and finances may influence the selection of treatment, but it is appropriate for practitioners to consider what they would do if this was their own mouth.

Treatment may include barrier membranes, autografts, allografts, xenografts, and alloplasts17–23 (Fig 1-12). The introduction of recombinant human platelet-derived growth factor BB (rhPDGF-BB) together with any of the previously mentioned materials has significantly improved the ability to achieve a successful outcome.23–29 Once again, it is necessary to consider the stability of the tooth and the morphology of the defect. The containment of the defect provided by remaining osseous structure provides the protection of the blood clot while it becomes organized and provides space maintenance for regeneration to occur. It is generally impossible to achieve periodontal regeneration when the defect morphology is completely horizontal, but it is possible for vertical osseous defects. The stability of the tooth is critical to accomplishing regeneration; therefore, stabilization of the tooth may be required before regeneration. It is necessary to consider the type of defect and identify the source of the progenitor cells and vascularity. Since almost every defect is a combination of one, two, and three walls, contained versus noncontained seems to be more meaningful terminology. What is important is to recognize the possibility of regenerating the lost periodontium rather than removing the tooth to place an implant when this is not necessary.22–28

Fig 1-12 (a) Presurgical evaluation demonstrates a probing depth of 9 mm with no bleeding and pink gingiva. (b) The intrabony defect is almost completely devoid of a buccal wall. (c) The radiograph demonstrates severe loss of osseous support, although the tooth is stable. (d) The graft material and recombinant human platelet-derived growth factor are placed into the osseous defect. (e) The clinical appearance after 3 days demonstrates initial healing. (f) The flap is reflected after 1 year and demonstrates regeneration of the osseous defect. (g) A 1-year radiograph demonstrates the premolar in contact with the canine and significant bone response. (h) A 6-year postoperative radiograph. (i) A 10-year postoperative radiograph. (j) The 10-year postoperative clinical appearance.

Since the definition of periodontal regeneration is a histologic demonstration of new cementum and bone as well as a periodontal ligament connecting them, it is important to select the appropriate grafting materials (Figs 1-13 and 1-14), whose predictability should be supported by clinical studies.26,28,29 There is abundant evidence to suggest long-term success with and without surgical treatment.

Fig 1-13 (a) An 8-mm probing depth with pink, non-bleeding tissue. (b) The histologic block section after 8 months. (c) Note the new cementum (NC), new periodontal ligament (PDL), and the new bone (NB). Very little graft material remains. Clinical enlargement of the middle block is observed. (d) The apical position of the junctional epithelium (JE) was prohibited by the connective tissue (CT) attachment. Note two small pink pieces occlusal to the new bone. This is the only evidence of the biologic after healing. (e) This is the result of conventional periodontal regeneration without rhPDGF. (f) This implant demonstrates osseointegration. (g) This regenerative result demonstrates new cementum and a strong periodontal ligament. However, the bone-to-implant contact is limited. OB, old bone; TR, trunk.

Fig 1-14 (a) There is a lingual Class II furcation involvement of the mandibular molar. (b) This is grafted with a bone allograft combined with rhPDGF-BB. (c) An overall histologic section of the molar following treatment of the Class II furcation. The green line demonstrates the difference between the very thin eruption cementum and the regenerative cellular cementum, which is broader. (d) A magnified view of the notch made at the level of bone. Once again, it is obvious that there is new cementum (NC), new periodontal ligament (PDL), and new bone (NB). The arrow demonstrates the thin, eruptive cementum and the thick, new cellular cementum to show periodontal regeneration. TR, trunk. (e) A magnified view focusing on the furcation regeneration.

The bone morphology will frequently dictate decision making in esthetic areas. Unfortunately, experience is required to make the decision, and even then it may be a compromise. The availability and efficacy of methods and materials available have expanded the possibilities of both successful implant placement and periodontal regeneration, which can complicate decision making. Results are achievable today that were unlikely to be seen in the past.

DECISION MAKING FOR SAVING THE NATURAL DENTITION

In the posterior dentition in which there is damage to tooth structure, periodontal disease associated with significant loss of alveolar structure, and/or the need for endodontic therapy, the most frequent clinical decisions are to treat and retain the natural dentition or place osseointegrated implants. Let us first consider the loss of bone support for multirooted teeth with furcation involvement. A Class I furcation should be addressed with the mindset of stopping the progress before it becomes a Class II furcation. This can be confidently achieved with reduction of the sulcus and perhaps minor osseous surgery. There is human histologic evidence to demonstrate periodontal regeneration in Class II furcations21–24 (see Fig 1-14). However, these were proof-of-principle studies and do not guarantee the goal will be achieved 100% of the time.

There is no clear human histologic evidence that the regeneration of Class III furcations can be expected using any current treatment regimens. Therefore, the next consideration is whether the tooth can be preserved with root resections over an extended period of time. The prognosis of root resection has been clearly demonstrated in previous publications.57–60 The dictating factors for this decision are the length of the clinical root and the size of the edentulous span. When there is a combination of a long root and a small edentulous distance, the likelihood for success is high (Figs 1-15 and 1-16). Conversely, short roots and long edentulous spans will have a much worse prognosis. The stopgap decision is crown-lengthening surgery to address the loss of tooth structure. However, the distance from the cementoenamel junction to the furcation is frequently no more than 4 to 5 mm. It is not wise to open the furcation by removing bone for crown lengthening, and extraction and replacement with an implant is logical.61,62 Of course, the saving grace is the rare instance when the roots are fused (Figs 1-17 and 1-18). Essentially, root resection converts furcated molars to single-rooted teeth with a favorable environment for oral hygiene.

Fig 1-15 (a) This mandibular molar had significant mesial caries and furcation involvement (arrow) in 1969. (b) The result after 25 years demonstrates the success of root resection of a multirooted tooth. Note the bone level (arrow).

Fig 1-16 (a) Both mandibular molars have Class III furcation invasion. (b) The finished prosthetic restoration. The retention of the apical portion of the mesial roots remains after 21 years. (c) Definitive restoration.

Fig 1-17 (a and b) This case predates osseointegration, and crown lengthening was necessary to construct a restoration with margins on healthy tooth structure. (c) The sutured position of the flaps. (d to g) Radiographs from 1976, 1977, 1980, and 2000, respectively. The tooth has served the patient’s masticatory needs for 24 years.

Fig 1-18 (a) Crown lengthening was performed with screws and composite. The gutta-percha cone (yellow arrow) demonstrates that the lingual cusps of the tooth fractured. It was decided that no further therapy should be performed for this tooth, and it would be replaced by dental implants. (b) The restored implants in 1992. (c) An updated radiograph in 2017, after 25 years.

Decisions for anterior single-rooted teeth are greatly influenced by esthetics. Mandibular intrabony defects can be successfully managed over a long period of time without encountering esthetic disappointment from the patient.63,64

There is significant evidence that teeth with reduced periodontium can provide successful mastication and patient satisfaction for many decades. As previously mentioned, the uninvited problem of peri-implantitis challenges earlier beliefs that implant success was expected to be in the 95th percentile.44,46,65–67 It is of utmost importance for the clinician to be cognizant of all therapeutic opportunities to arrive at the best solution for the patient.

Similar decisions are involved in endodontic treatment of single-rooted mandibular teeth or defects in tooth structure that require crown lengthening. It is necessary to become knowledgeable about contemporary endodontic therapy supported by evidence-based dentistry in order to be successful when compromised teeth are saved and remain part of the natural dentition (Figs 1-19 and 1-20).

Fig 1-19 (a) Preoperative view showing previous endodontic treatment failure accompanied by a lateral periodontal lesion. (b) Following retreatment with biocompatible bioceramics. Notice the lateral canals. (c) Complete resolution of the lesion.

Fig 1-20 (a) Preoperative view of periapical pathosis. (b) Following endodontic treatment with biocompatible bioceramics. (c) Postoperative view of complete resolution of periapical pathosis.

Some of the technologic advancements that enable us to save teeth include the surgical operating microscope, nickel-titanium instrumentation, apex locators, ultrasonics, mineral trioxide aggregate, hydrodynamic irrigation, bioceramics, and cone beam computed tomography.

ESTHETIC CONSIDERATIONS

Many contemporary patients identify esthetic improvement as their motivating factor to seek dental care. Although the esthetic region includes the maxillary and mandibular anterior teeth, most individuals’ display area focuses on the maxillary region. It is important for the dentist to be cognizant of the patient’s wishes and whether or not they are realistic and to explain the difficulty of the procedure and the need to satisfy both esthetic and biologic goals for long-term success, as this may be the discerning factor. Every effort should be made to provide clinical and radiographic documentation that will enhance the diagnosis and planning of an optimal result.

The esthetic restoration of a single tooth is identified by the patient as one that matches the shade and size of the adjacent teeth (see Figs 1-2 and 1-11). Patients are generally dissatisfied with interproximal black triangles, which may be present with a single tooth- or implant-supported restoration. Esthetic restoration is a realistic goal when a tooth is lost to fracture from trauma or endodontic failure. A fractured tooth may require a crown-lengthening procedure to provide sound tooth structure for the cervical margin of a new crown. This may be accomplished with soft tissue excision but usually requires some removal of bone. In these instances, esthetics may be optimized by preserving the bone, extracting the damaged tooth, and replacing it with an implant (see Fig 1-2).

All patients would prefer the restoration to re-create their natural, younger appearance, and all dentists would like to accommodate this request. Therefore, it can be helpful to ask the patient to provide a photograph from the past to help in planning the restoration.

The conflict between the desire for longevity and the desire for esthetics can complicate treatment. Perhaps the most difficult treatment plan involves the patient with a large dental display and a significant loss of supporting structure for the remaining teeth (Fig 1-21). However, esthetic goals can be realized even with a high lip line. It is important to create a prosthesis that allows access for oral hygiene. A primary goal is to preserve the bone-implant contact, and this can be accomplished with the use of pink ceramics to effectively emulate the papillae. The evidence of success can be established radiographically by comparing the bone-implant contact over a period of years (Fig 1-22).

Fig 1-21 (a) The patient’s chief complaint centers on esthetics, but she is unaware of her advanced loss of periodontium. (b) It is evident that there has been a significant loss of supporting bone for these teeth. (c) If implants are placed without significant successful regenerative therapy, the implant- abutment junction will be too apical to allowing cleaning by the patient or the hygienist. The decision was made to remove the teeth and place a provisional partial denture. (d) Radiographs showing the loss of bone. (e) If a patient is susceptible to inflammation, it is important to have structures in a position where the hygienist and patient can decontaminate the components of the restoration, such as the implant abutment and prosthetic restoration.

Fig 1-22 When a patient has a high lip line and significant loss of periodontium, esthetic treatment is of prime importance. It is necessary to construct a prosthesis that will allow oral hygiene access for the patient and the hygienist. (a to c) This patient always had spaces between her teeth, so she met with the dental technician to create a solution. She has a high lip line with significant dental display. (d and e) Intraoral and smile views 22 years later. (f) Radiograph from 1992. Note within the red circle the preservation of all of cervical bone because the patient has adequate oral hygiene access. (g) Radiograph taken 24 years later. (h) The patient’s esthetic display due to her high lip line in 2018. (i) The patient performing using dental floss in 2018.

If periodontally compromised maxillary incisors are to be removed, an alternative to implants may be constructing a fixed partial denture from canine to canine (Fig 1-23). This will preserve the soft tissue papillae and prevent the need to place implants at the level of bone, which would result in the implant-abutment junction being placed significantly subgingivally. A prosthesis with limited oral hygiene access would be a poor choice for the patient who has lost periodontium because of susceptibility to inflammation. In addition, not every patient is an appropriate candidate for distraction osteogenesis or guided bone regeneration.

Fig 1-23 (a) The patient presented with esthetic and phonetic complaints. All four maxillary incisors were replaced with pontics. (b) The solution to the problem was prosthetic reconstruction with no dental implants.

SUMMARY

It is important for dental practitioners to expand their horizons if and when patients demand to preserve their remaining dentition. It is critical to provide an outcome that allows adequate access for daily oral hygiene and a personalized maintenance program based on the patient’s demonstrated susceptibility to inflammatory disease. It is equally important to have the ability to deliver even the most challenging esthetic and functional prostheses (Fig 1-24).

Fig 1-24 (a to d) This 45-year-old man presented with advanced periodontal disease and all of his teeth were mobile. However, he did not want implant treatment. The maxillary molars were beyond treatment and the remaining teeth had very short clinical roots. The mandibular molars had Class 3 furcation invasions. The lateral views demonstrates gingival recession on all of the teeth. On the left side, the teeth were splinted to stabilize them during initial debridement treatments.

(e and f) Clinical view and radiographic survey after treatment was concluded. The patient wanted to keep this status for 5 years. (g and h) Clinical view and radiographic survey 26 years later demonstrating the possibility of long-term benefits for the patient.

The most alluring part of the dental profession is that treatment regimens continue to improve and benefit the patient. There is no factor in treatment more important than developing the treatment plan. Dental practitioners have the opportunity for a rewarding career when they use their knowledge to create a satisfied patient.

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2

From Osseointegration to Predictable Long-Term Implant Stability: Clinicians’ Perspectives

The Development and Predictability of Osseointegrated Implants

MYRON NEVINS

Long-Term Results of Implants in Native and Regenerated Bone

MASSIMO SIMION

Connective Tissue Attachment to a Laser-Microtextured Surface

CARY A. SHAPOFF

Long-Term Implant Success: Part I

JEFFREY GANELES • FREDERIC J. NORKIN • LILIANA ARANGUREN • SAMUEL ZFAZ

Long-Term Implant Success: Part II

DAVID M. KIM • WONBAE PARK

Long-Term Implant Success: Part III

TAMSIN J. CRACKNELL • DEON FERREIRA • PETER HAWKER • ANDREW ACKERMANN

The Development and Predictability of Osseointegrated Implants

MYRON NEVINS

Although dental implants were first introduced to the profession in the 1950s, they were not readily accepted by the profession because of a lack of investigations and questionable predictability. This author’s experience with dental implants has involved three distinct eras:

1. 1966 to 1984: Subperiosteal implants, blade implants, and a variety of intrabony implants.

2. 1984 to 2000: A high percentage of implants with machined surfaces. There were significant advances as a result of clinical investigations and biologic research. A transition occurred, with a change from edentulous reconstruction to implants being used to treat the partially dentate patient. Most clinicians placing implants had extensive surgical credentials, resulting in extraordinarily high success rates. 1–3

3. 2000 to 2018: Expansion of the industry with many new companies emerging and implants being placed by clinicians with varied levels of surgical training.

The author’s experience with subperiosteal implants ended in 1984. They were most predictable with advanced atrophy of the edentulous mandible. When successful, patients reported an enhanced lifestyle with comfort, a return of long-lost mastication, and improved personal confidence4 (Fig 2-1). Success was later experienced in treating partial edentulism, but not at a high level of predictability4 (Fig 2-2). They served to provide support for fixed prosthetic restorations and greatly reduced the use of removable partial dentures.

Fig 2-1 A mandibular subperiosteal implant placed in 1968. The patient died in 2010. This implant restoration provided 42 years of masticatory function and improved personal confidence.

Fig 2-2 (a) This pseudo-Class III malocclusion with a loss of vertical height required occlusal support in the mandibular left posterior quadrant. (b) Provisional restorations reestablished an acceptable occlusion. (c) The extension of the mandibular left quadrant would require a removable partial denture or a dental implant in 1971. (d) The subperiosteal implant. (e) The definitive fixed prostheses. (f) The left lateral view demonstrating a full gold crown on the implant. A screw was placed on the mesial surface into a small slot on the implant to prevent it from becoming loose. (g) The full-mouth radiographic survey at the completion of treatment. (h) A full-mouth radiographic survey after 21 years.

Likewise, osseointegrated implant treatment was somewhat limited to addressing complete edentulism at the time of introduction, but it rapidly became useful and predictable for replacement of a single tooth or quadrant5–8 (Figs 2-3 and 2-4). From the year 2000 to the present, much research has been focused on modifications to implant surfaces and abutments. Another focus of research has been peri-implantitis, which has been addressed in periodical publications, textbooks, and at the podium of every dental meeting.

SUCCESS AND SURVIVAL

Criteria for success were recognized in 1986 and have not yet been significantly updated by the dental community.9 There is some conflict between these criteria for success and the demonstration of survival. It is truly believed that success can be accomplished, and every effort should be made to implement this goal. The radiographic measurement of success is bone-implant contact with little or no change in bone level over time (Figs 2-3 to 2-5). Clinical success includes continued support not only of the implant but also of the restorations, an issue that is of great concern for the patient. Esthetics are important to most patients, who generally are not satisfied if interproximal black triangles or gingival recession occur. The final evidence of success would be histologic, ie, evidence of bone-implant contact. This path begins with optimal preclinical results that can be translated into clinical research for patient treatment, which will later be translated to exceptional patient benefits.

Fig 2-3 (a) Full-mouth radiographic survey in 1988. (b) It was necessary to replace both fixed prostheses in the mandible and maxilla. (c) Left lateral view of implants replacing the maxillary left premolars.

(d) Note the metal residue from the previous apicoectomy. (e) The clinical picture demonstrating a good keratinized gingiva level after 28 years. (f) Radiograph taken in 2016. The position of the metal artifact documents the stability of the bone. The sectioned molar was replaced with two additional implants.

Fig 2-4 (a) An implant was placed at bone level in 1989. (b) A clinical photograph demonstrating a high lip line. (c) The 25-year radiograph demonstrates no bone loss over this period of time. (d) Clinical observation after 25 years. The interdental papillae are in place (green arrows), so it was not necessary to place the implant further apically to achieve an esthetic result.

Fig 2-5 (a) Intraoral view of a 32-year-old man with a history of periodontal disease and previous periodontal surgery. (b) A 1991 full-mouth radiographic survey. The decision was made to replace the maxillary teeth with a fixed implant prostheses. Every effort was made to retain the mandibular posterior teeth, and the mandibular incisors were replaced with a fixed partial denture. (c) A 2006 full-mouth radiographic survey demonstrating an excellent level of implant support. The remaining mandibular posterior teeth were mobile and demonstrated continuing loss of bone. (d) Full-mouth radiographs after 26 years. All four premolars and the left first molar were replaced with implant prostheses. The excellent level of crestal bone continued. (e) The clinical prostheses in place. (f) The maximum tooth display in the patient’s smile.

SURGICAL VARIABLES

The surgical variables in implant treatment include the following:

•Selection of implants

•The level of the implant shoulder in relation to the bone

•Tooth position in the dental arch

•Appropriate preparation of osteotomy

•Amount of compression at placement

In terms of implant selection, most implant companies have manufactured their products carefully and upgraded consistently. There is no effort on the part of this chapter’s authors to guide the reader to use any particular implant system. Rather, the goal is to show how clinical success has been achieved using many different systems, and the choice of implant depends on clinician preference and experience as well as the specific needs of a given patient.

Once the implant has been selected, there are other factors that greatly influence the result. One of these is the position of the implant as it relates to the volume of bone, and cone beam computed tomography (CBCT) has provided the opportunity to investigate the proposed implant position prior to placement10 (Fig 2-6). The introduction of digital dentistry allows this information to be transferred to surgery via surgical stents. Such guided surgery may not be necessary for every implant, but the digital planning process can help guide surgical decisions11,12 (Fig 2-7). This is especially important in cases of thin ridges in nonsurgical implant placement in which the diameter of the implant is barely contained by the volume of bone. Preclinical studies have suggested three possible locations of the implant’s coronal surface in bone: at, above, or below the level of bone13 (Fig 2-8). Clinical experience suggested that the collar of the implant should be placed at the bone level (see Figs 2-3 and 2-4). Considering information from preclinical studies,13 one might even place the polished collar of an implant above the cervical bone level (Figs 2-9 and 2-10). In clinical practice, it is very unusual to place an implant in completely level bone without performing bone reduction, which may be done according to the lingual/palatal and interproximal levels of bone (Fig 2-11).

Fig 2-6 (a) Example of a tooth whose extraction would allow implant placement in an appropriate position. (b) Example of a tooth position that would not allow successful implant placement. (c) Patient presents with maxillary and mandibular protrusion. (d) The mandibular left canine shown in c appears to be buccal to the alveolar process.

Fig 2-7 (a) Imaging demonstrates extreme bone loss around the mandibular anterior teeth. Lack of patient diligence in maintaining the teeth led to a situation in which it was imperative to remove the remaining anterior mandibular teeth and place implants. A navigation system produced a stent that dictated the position of the implants. (b) The extraction sockets after all granulation tissue was removed. (c) Implant placement dictated by the stent. (d) The implants in place prior to regenerative procedures. (e) Radiographs taken 4 years after the implants were placed.

Fig 2-8 A 1997 preclinical study13 compared implants placed at the bone level (a), 1 mm above the bone level (b), or 1 mm below the bone level (c). For all two-piece implants, whether nonsubmerged or submerged, the most coronal bone-implant contact was located approximately 2 mm below the microgap. The result is that the least amount of bone loss occurred when the implant was placed above the bone level (b), and the most loss of bone occurred when it was placed below the level of bone (c).

Fig 2-9 (a) The maxillary right lateral incisor is a candidate for extraction. (b) The lateral incisor was extracted, after which a provisional partial denture was placed. Vertical and horizontal bone augmentations were performed. (c) The result of the regeneration procedure. The implant has an external hex and a polished 1-mm collar that was placed above the bone level (circle). (d) Clinical image of the finished prostheses in 1994, showing the patient’s limited display. (e) Intraoral view of the definitive restoration in 1994. (f) After 12 years, the papillae are in place, and there is no recession on the lateral incisor. There is minor recession on the adjacent natural canine (arrow).

Fig 2-10 (a) The patient was referred for an implant to replace the maxillary left lateral incisor in 1991. The author’s team considered replacing the central incisors and using a cantilever to restore the left lateral incisor, but the patient was adamant about retaining the central incisors. (b) An implant was placed with the polished collar above the bone level. (c) Clinical radiograph in 2016. The crestal bone remained the same after 25 years. (d) Extraoral view in 2016 showing maximum esthetic display. (e) Intraoral view in 2016 showing adequate keratinized mucosa and the interdental papillae remaining in place.

Fig 2-11 (a) A 19-year-old woman presented with a maxillary left canine with a fistula. (b) The tooth and buccal bone after flap reflection. (c) The interproximal bone level is approximately 1 to 2 mm apical to a line joining the cementoenamel junctions. (d) The palatal bone level is approximately the same as the interproximal bone level. (e) There is a deficiency of buccal bone. (f) A healing abutment is placed, and the buccal flap is coronally positioned. (g) The lip line and the smile display. (h) Close-up view of the result. (i) Intraoral view of the healed result. (j) Radiograph taken in 1998, after crown delivery. (k) Radiograph taken in 2007. (l) Radiograph taken in 2013. Note the crestal bone level.

It is very important to place the implant following the directions of the manufacturer. Every effort should be taken not to overheat the bone during implant placement, although the value of compression on the bone is unclear.14 It was impossible to recruit enough human donors to study the effects of compression, so the author and his colleagues performed a canine study. It is very interesting to see the difference in bone-implant contact in this model from day 0 to day 56 (Fig 2-12).14 The author and his team also have been fortunate to have the opportunity to compare bone-implant contact in localized autogenous edentulous sites compared with extraction sockets. The comparison shows the bone-implant contact to be 74.5% (Fig 2-13) for the edentulous region and 66.2% for the extraction socket15,16 (Fig 2-14). The author believes either choice allows for implant stability, but results will vary with the degree of bone trabeculation in the implant placement site.

Fig 2-12 A preclinical canine study of the effects of bone compression on implant osseointegration. The radiographs show very little difference from day 0 to day 56, but the histologic images show that the bone-implant contact develops from 17% at 0 hour to 74% at day 56.

Fig 2-13 Four autogenous human bone blocks 6 months after implant placement in edentulous ridges. The bone-implant contact is estimated to be 74.5%. (Reprinted from Nevins et al15 with permission.)

Fig 2-14 Five examples of autogenous biopsies after implants were immediately placed in extraction sockets. Bone-implant contact is 66.2%. (Reprinted from Nevins et al16 with permission.)

CONCLUSION

The purpose of this chapter is to demonstrate the predictability of osseointegrated implant treatment to restore function, esthetics, and phonetics over the long term. It demonstrates results over a significant period of time from a variety of clinicians using different implant systems. There is overwhelming evidence that successful implant treatment can be achieved, not only for young, healthy patients, but also for patients with susceptibility to inflammation demonstrated by bone loss around their natural dentition (Figs 2-5 and 2-15). It is optimistic to assume that every patient will practice ideal oral hygiene habits, and there are some geographic areas with no trained dental hygienists17–19 (Fig 2-16). The combination of these limitations are potentiated when implants are placed too far subgingivally or interproximal spaces are blocked out so that hygiene access is impossible. Therefore, the responsibility of establishing success is greatly influenced by the treatment planning of the multidisciplinary team of clinicians involved in patient care.

Fig 2-15 (a) Full-mouth radiographic survey demonstrating tooth loss and moderate periodontal disease in 1986, prior to implant treatment. (b) Radiographic survey after 5 years. (c) Periapical radiographs after 20 years. There is some small evidence of countersinking, which was routine in 1986.

Fig 2-16 (a) An anterior view demonstrating a patient’s capability of practicing proper oral care. The patient does not have a high lip line and is ecstatic that no teeth needed to be removed. (b) Right lateral view showing significant loss of support but a level of hygiene that demonstrates that a patient can be a partner in long-term periodontal success.

Long-Term Results of Implants in Native and Regenerated Bone

MASSIMO SIMION

P-I Brånemark was performing preclinical studies on bone physiology when he was a professor of anatomy at the University of Gothenburg in Sweden. In order to create in vivo observational studies, he used titanium optical chambers placed in rabbit tibiae to observe the behavior of blood vessels under different conditions. The titanium chambers were supposed to be removed at the end of the study and implanted in different rabbits, but the impossibility of detaching the titanium chambers from the tibial bone led him to investigate the micro-characteristics of the interface of bone and titanium. It was by chance that the biologic principle of osseointegration was thus discovered.

Data from preclinical and clinical studies were presented to the scientific community during the Dental Implant Consensus Conference held in Toronto in 1978 organized by the National Institutes of Health (NIH) and Harvard University. This event brought new recognition to the Brånemark osseointegrated implant system and, eventually, changed the approach to dental treatment planning. The system was based on the use of commercially pure titanium root-form implants with a machined surface and a very strict two-stage surgical protocol in which the implant was submerged for 3 months in the mandible and 6 months in the maxilla before prosthetic functional loading. This system was successfully used for the treatment of millions of patients around the world for 20 years.

IMPLANTS PLACED IN NATIVE BONE

The first study was presented by Adell et al at the NIH Implant Consensus Conference in Toronto in 1978 and published in 1981.20 The authors demonstrated a survival rate of 81% in the maxilla and 95% in the mandible. It was at the beginning of the learning curve, and the follow-up period was from 5 to 10 years. The implants placed later in the 1980s showed a survival rate of 95% in the maxilla and 99% in the mandible after 4 years of