In the 1960s and 1970s, implant‐supported prostheses based on subperiosteal or blade implants had a poor reputation because of questionable clinical outcomes and lack of scientific documentation. The ...change to a scientifically sound discipline was initiated by the two scientific pioneers of modern implant dentistry, Professor P. I. Brånemark from the University of Gothenburg in Sweden and Professor André Schroeder from the University of Bern in Switzerland. Together with their teams, and independently of each other, they laid the foundation for the most significant development and paradigm shift in dental medicine. The present volume of Periodontology 2000 celebrates 50 years of osseointegration. It reviews the progress of implant therapy over the past 50 years, including the basics of implant surgery required to achieve osseointegration on a predictable basis and evolving innovations. The development of bone‐augmentation techniques, such as guided bone regeneration and sinus floor elevation, to correct local bone defects at potential implant sites has increased the indications for implant therapy. The paradigm shift to moderately rough implant surfaces resulted in faster and enhanced bone integration and led to improvements in various treatment protocols, such as immediate and early implant placement in postextraction sites, and made various loading protocols possible, including immediate and early implant loading. In the past 15 years, preoperative analysis and presurgical planning improved as a result of the introduction of three‐dimensional imaging techniques. Hereby, cone‐beam computed tomography offers better image quality with reduced radiation exposure, when compared with dental computed tomography. This opened the door for digital planning and surgical modifications. Over the last 50 years this evolution has facilitated tremendous progress in esthetic outcomes with implant‐supported prostheses and improved patient‐centered outcomes. This volume of Periodontology 2000 also discusses the current trends and open questions of implant dentistry, such as the potential of digital implant dentistry in the surgical and prosthetic field, the trend for an increasing average age of implant patients and the related adaptations of treatment protocols, and the second attempt to establish ceramic implants using, this time, zirconia as the implant material. Finally, some of the hottest controversies are discussed, such as recent suggestions on bone integration being a potential foreign‐body reaction and the evidence‐based appraisal of the peri‐implantitis debate.
The objectives of this systematic review are (1) to quantitatively estimate the esthetic outcomes of implants placed in postextraction sites, and (2) to evaluate the influence of simultaneous bone ...augmentation procedures on these outcomes.
Electronic and manual searches of the dental literature were performed to collect information on esthetic outcomes based on objective criteria with implants placed after extraction of maxillary anterior and premolar teeth. All levels of evidence were accepted (case series studies required a minimum of 5 cases).
From 1,686 titles, 114 full-text articles were evaluated and 50 records included for data extraction. The included studies reported on single-tooth implants adjacent to natural teeth, with no studies on multiple missing teeth identified (6 randomized controlled trials, 6 cohort studies, 5 cross-sectional studies, and 33 case series studies). Considerable heterogeneity in study design was found. A meta-analysis of controlled studies was not possible. The available evidence suggests that esthetic outcomes, determined by esthetic indices (predominantly the pink esthetic score) and positional changes of the peri-implant mucosa, may be achieved for single-tooth implants placed after tooth extraction. Immediate (type 1) implant placement, however, is associated with a greater variability in outcomes and a higher frequency of recession of > 1 mm of the midfacial mucosa (eight studies; range 9% to 41% and median 26% of sites, 1 to 3 years after placement) compared to early (type 2 and type 3) implant placement (2 studies; no sites with recession > 1 mm). In two retrospective studies of immediate (type 1) implant placement with bone graft, the facial bone wall was not detectable on cone beam CT in 36% and 57% of sites. These sites had more recession of the midfacial mucosa compared to sites with detectable facial bone. Two studies of early implant placement (types 2 and 3) combined with simultaneous bone augmentation with GBR (contour augmentation) demonstrated a high frequency (above 90%) of facial bone wall visible on CBCT. Recent studies of immediate (type 1) placement imposed specific selection criteria, including thick tissue biotype and an intact facial socket wall, to reduce esthetic risk. There were no specific selection criteria for early (type 2 and type 3) implant placement.
Acceptable esthetic outcomes may be achieved with implants placed after extraction of teeth in the maxillary anterior and premolar areas of the dentition. Recession of the midfacial mucosa is a risk with immediate (type 1) placement. Further research is needed to investigate the most suitable biomaterials to reconstruct the facial bone and the relationship between long-term mucosal stability and presence/absence of the facial bone, the thickness of the facial bone, and the position of the facial bone crest.
Bone healing around dental implants follows the pattern and sequence of intramembraneous osteogenesis with formation of woven bone first of all followed later by formation of parallel‐fibered and ...lamellar bone. Bone apposition onto the implant surface starts earlier in trabecular bone than in compact bone. While the first new bone may be found on the implant surface around 1 week after installation, bone remodeling starts at between 6 and 12 weeks and continues throughout life. Bone remodeling also involves the bone–implant interface, thus transiently exposing portions of the implant surface. Surface modifications creating micro‐rough implant surfaces accelerate the osseointegration process of titanium implants, as demonstrated in numerous animal experiments. Sandblasting followed by acid‐etching may currently be regarded as the gold standard technique to create micro‐rough surfaces. Chemical surface modifications, resulting in higher hydrophilicity, further increase the speed of osseointegration of titanium and titanium‐zirconium implants in both animals and humans. Surface modifications of zirconia and alumina‐toughened zirconia implants also have an influence on the speed of osseointegration, and some implant types reach high bone‐to‐implant contact values in animals. Although often discussed independently of each other, surface characteristics, such as topography and chemistry, are virtually inseparable. Contemporary, well‐documented implant systems with micro‐rough implant surfaces, placed by properly trained and experienced clinicians, demonstrate high long‐term survival rates. Nevertheless, implant failures do occur. A low percentage of implants are diagnosed with peri‐implantitis after 10 years in function. In addition, a low number of implants seem to be lost for primarily reasons other than biofilm‐induced infection. Patient factors, such as medications interfering with the immune system and bone cells, may be an element contributing to continuous bone loss and should therefore be monitored and studied in greater detail.
The key to achieving pleasing esthetics in implant dentistry is a thorough understanding of the biological processes driving dimensional bone and soft tissue alterations post‐extraction. The aim of ...the present report is first to characterize the extent of bone and soft tissue changes post‐extraction and second to identify potential factors influencing tissue preservation in order to facilitate successful treatment outcomes. The facial bone wall thickness has been identified as the most critical factor influencing bone resorption and can be used as a prognostic tool in order to identify sites at risk for future facial bone loss subsequent to tooth extraction. Clinical studies indicated that thin bone wall phenotypes exhibiting a facial bone wall thickness of 1 mm or less revealed progressive bone resorption with a vertical loss of 7.5 mm, whereas thick bone wall phenotypes showed only minor bone resorption with a vertical loss of 1.1 mm. This is in contrast to the dimensional soft tissue alterations. Thin bone wall phenotypes revealed a spontaneous soft tissue thickening after flapless extraction by a factor of seven, whereas thick bone wall phenotypes showed no significant changes in the soft tissue dimensions after 8 weeks of healing. In sites exhibiting a limited bone resorption rate, immediate implant placement may be considered. If such ideal conditions are not present, other timing protocols are recommended to achieve predictable and pleasing esthetics. Socket preservation techniques for ridge preservation utilizing different biomaterials and/or barrier membranes often result in a better maintenance of tissue volumes, although the inevitable biological process of post‐extraction bone resorption and bone modeling cannot be arrested. In summary, the knowledge of the biological events driving dimensional tissue alterations post‐extraction should be integrated into the comprehensive treatment plan in order to limit tissue loss and to maximize esthetic outcomes.
Implant placement in post‐extraction sites of single teeth in the esthetic zone has been a topic of great interest in the field of implant dentistry since 1990. Triggered by the development of guided ...bone regeneration, the concept of immediate implant placement became quite popular in the 1990s. In the past 12 years, however, the dental community has begun to focus increasingly on the esthetic outcomes of post‐extraction implant placement and several studies indicated a significant risk for the development of mucosal recessions with immediate implants. Parallel with this, significant progress has been made in the understanding of tissue biology in terms of hard and soft tissue alterations post extraction, based on preclinical, clinical and radiological studies. This knowledge has helped better to understand the etiology of these esthetic complications with immediate implant placement. The present review first analyzes the various phases of the development of therapeutic strategies over the years for post‐extraction implant placement in single tooth sites in the esthetic zone. It presents the current knowledge concerning the terminology with immediate, early and late implant placement, the risk factors for the development of esthetic complications, and the selection criteria for the various treatment options. In the second part, clinical recommendations are given, since a clinician active in this field of implant therapy can use all treatment options depending on the preoperative analysis including a 3D cone beam computed tomography. The selection criteria for all four treatment options are presented and documented with typical case reports to illustrate the current treatment approaches applied in daily practice.
In the developed world, the large birth cohorts of the so‐called baby boomer generation have arrived in medical and dental practices. Often, elderly patients are ‘young‐old’ baby boomers in whom ...partial edentulism is the predominant indication for implant therapy. However, the generation 85+ years of age represents a new challenge for the dental profession, as their lives are frequently dominated by dependency, multimorbidity and frailty. In geriatric implant dentistry, treatment planning is highly individualized, as interindividual differences become more pronounced with age. Nevertheless, there are four typical indications for implant therapy: (i) avoidance of removable partial prostheses; (ii) preservation of existing removable partial prostheses; (iii) stabilization of Kennedy Class I removable partial prostheses; and (iv) stabilization of complete prostheses. From a surgical point of view, two very important aspects must be considered when planning implant surgery in elderly patients: first, the consistent strive to minimize morbidity; and, second, the fact that coexisting medical risk factors are significantly more common in elderly patients. Modern three‐dimensional cone beam computed tomography imaging is often indicated in order to plan minimally invasive implant surgery. Computer‐assisted implant surgery might allow flapless implant surgery, which offers a low level of postoperative morbidity and a minimal risk of postsurgical bleeding. Short and reduced‐diameter implants are now utilized much more often than a decade ago. Two‐stage surgical procedures should be avoided in elderly patients. Implant restorations for elderly patients should be designed so that they can be modified to become low‐maintenance prostheses, or even be removed, as a strategy to facilitate oral hygiene and comfort in the final stage of life.
There is a lack of knowledge concerning the critical buccal bone thickness required for securing favorable functional and esthetic outcomes, conditioned to the dimensional changes after implant ...placement. A preclinical study was therefore carried out to identify the critical buccal bone wall thickness for minimizing bone resorption during physiologic and pathologic bone remodeling.
A randomized, two-arm in vivo study in healthy beagle dogs was carried out. The first group of dogs was sacrificed 8 weeks after implant placement for histomorphometric examination of postsurgical resorption of the buccal bone wall. The second group of dogs was monitored during three ligature-induced peri-implantitis episodes and a spontaneous progression episode. Morphometric and clinical variables were defined for the study of physiologic and pathologic buccal and lingual bone loss.
Seventy-two implants were placed in healed mandibular ridges of 12 beagle dogs. Two groups were defined: 36 implants were placed in sites with a thin buccal bone wall (< 1.5 mm), and 36 were placed in sites with a thick buccal bone wall (≥ 1.5 mm). No implants failed during the study period. For the great majority of the histomorphometric parameters, a critical buccal bone wall thickness of at least 1.5 mm seemed to be essential for maintaining the buccal bone wall during physiologic and pathologic bone resorption. Suppuration (+) and mucosal recession (-) were more often associated with implants placed in sites with a thin buccal bone wall.
A critical buccal bone wall thickness of 1.5 mm at implant placement is advised, since a thicker peri-implant buccal bone wall (> 1.5 mm) is exposed to significantly less physiologic and pathologic bone loss compared with a thinner buccal bone wall (< 1.5 mm).
Objective
The aim of this study was to evaluate the effect of guided sleeve height, drilling distance, and guided key height on accuracy of static Computer‐Assisted Implant Surgery (sCAIS).
Materials ...and Methods
Pre and post‐operative positions of implants placed in duplicate dental models were compared and recorded after placement of implants according to a standardized treatment planning and execution sCAIS protocol. Guided sleeve heights: 2 mm, 4 mm, 6 mm and guided key heights: 1 mm and 3 mm were equally randomized in six test groups with varying implant lengths (10‐16 mm) and surgical drilling protocols. The mean crestal and apical three‐dimensional (3D) deviation, as well as the angular deviation were calculated for each group. Data was analyzed using multivariate analysis anova. P values less than .05 were considered statistically significant. All P values of post‐hoc tests were corrected for multiple testing using Bonferroni‐Holm's adjustment method.
Results
3D implant positioning accuracy was not significantly affected by the difference in sleeve height alone or by the implant length alone (P > .05). However, 3D and angular deviation values became significantly higher as the total drilling distance below the guided sleeve increased and significantly became lower as the guided key height above the sleeve increased. 18 mm drilling distance resulted in a significantly higher deviation, when compared to 14 mm or 16 mm drilling distances, irrespective of sleeve height or implant length (P < .01). 3 mm key height resulted in significantly less 3D deviation than 1 mm key height (P < .01).
Conclusion
Decreasing the drilling distance below the guided sleeve, by using shorter sleeve heights or shorter implants can significantly increase the accuracy of sCAIS.
Objectives
To evaluate the patient population over a 3‐year period and to compare it to observations of the population at the same clinic over a period of 15 years.
Material and Methods
Records of ...patients receiving dental implants in the Department of Oral Surgery and Stomatology, University of Bern, between January 2014 and December 2016 were analyzed and then compared with data from patients treated between 2002 and 2004 and between 2008 and 2010. Patients were analyzed for demographics and for indications for therapy, as well as for presence or absence and type of complications. Inserted implants were analyzed for type, length, and diameter, as well as for the number and type of associated tissue regeneration procedures.
Results
Analysis revealed a continuous linear increase in the average age of patients seeking implant treatment. The most common indication for implant therapy was a single‐tooth gap (STG) (50.5%), followed by distal extension situations (22.3%) and extended edentulous gaps (20.5%). A total of 60.8% of implants placed needed some type of bone augmentation, and 83.5% of implants placed in the anterior maxilla required simultaneous augmentation. Staged guided bone regeneration (GBR) was only necessary in 7% of the cases. Implant failure rates remained low at 0.6%, with postoperative hematomas being the most common postoperative complication (13.4%).
Conclusions
The rising demand for dental implants continues as the patient population ages. Single‐tooth gaps remained consistently the most common indication for implant therapy in recent years. Proper case selection and evidence‐based surgical protocols are essential for high success rates.
Objectives
The aim of the study was to investigate the impact of two hyaluronan (HA) formulations on the osteogenic potential of osteoblast precursors.
Materials and methods
Proliferation rates of ...HA-treated mesenchymal stromal ST2 and pre-osteoblastic MC3T3-E1 cells were determined by 5-bromo-20-deoxyuridine (BrdU) assay. Expression of genes encoding osteogenic differentiation markers, critical growth, and stemness factors as well as activation of downstream signaling pathways in the HA-treated cells were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunoblot techniques.
Results
The investigated HAs strongly stimulated the growth of the osteoprogenitor lines and enhanced the expression of genes encoding bone matrix proteins. However, expression of late osteogenic differentiation markers was significantly inhibited, accompanied by decreased bone morphogenetic protein (BMP) signaling. The expression of genes encoding transforming growth factor-β1 (TGF-β1) and fibroblast growth factor-1 (FGF-1) as well as the phosphorylation of the downstream signaling molecules Smad2 and Erk1/2 were enhanced upon HA treatment. We observed significant upregulation of the transcription factor Sox2 and its direct transcription targets and critical stemness genes, Yap1 and Bmi1, in HA-treated cells. Moreover, prominent targets of the canonical Wnt signaling pathway showed reduced expression, whereas inhibitors of the pathway were considerably upregulated. We detected decrease of active β-catenin levels in HA-treated cells due to β-catenin being phosphorylated and, thus, targeted for degradation.
Conclusions
HA strongly induces the growth of osteoprogenitors and maintains their stemness, thus potentially regulating the balance between self-renewal and differentiation during bone regeneration following reconstructive oral surgeries.
Clinical relevance
Addition of HA to deficient bone or bony defects during implant or reconstructive periodontal surgeries may be a viable approach for expanding adult stem cells without losing their replicative and differentiation capabilities.
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