Three Factors for Long-Term Dental Implant Success: Up to 40-year Follow-up

This article provides clinicians with 3 main factors that relate to long-term success. Long term in this article represents the lifespan of the patient, often requiring more than 40 years of function on the implant restoration. Literature is reviewed and used to provide evidence for these recommendations. Cases are presented to demonstrate these critical factors.

Effects of hard- and/or soft-tissue grafting with early implant placement: Histomorphometric outcomes of an exploratory study in canines

OBJECTIVE

To histomorphometrically determine the effects of hard- and/or soft-tissue augmentation by applying the early implant placement protocol.

MATERIALS AND METHODS

The distal roots of the maxillary second and third premolars were extracted in 10 mongrel dogs. After 1 month, early implant placement was performed in the distal roots, resulting in buccal dehiscence defects. Four treatments were then randomly applied: (1) guided bone regeneration (GBR), (2) connective tissue grafting (CTG), (3) simultaneous GBR and CTG (GBR + CTG) and (4) no further treatment (control). Healing abutments were connected to all implants to allow non-submerged healing. At 4 and 16 weeks, tissue sections were harvested and histomorphometric analyses were performed.

RESULTS

Group GBR presented the largest total tissue thickness at 4 weeks, but underwent a greater remodelling compared with the other groups between 4 and 16 weeks. At 16 weeks, the overall tissue thickness was largest in group GBR + CTG. This group was also the most favourable in terms of the level of the margo mucosae and the presence of mineralized tissue at the coronal level. Group CTG demonstrated a stable tissue thickness over time, with a larger thickness at 16 weeks compared with group GBR.

CONCLUSION

Simultaneous CTG and GBR resulted in the most-favourable tissue thickness when applying the early implant placement protocol.

In vivo measurement of three-dimensional load exerted on dental implants: a literature review

Background

For biomechanical consideration of dental implants, an understanding of the three-dimensional (3D) load exerted on the implant is essential, but little information is available on the in vivo load, including the measuring devices.

Purpose

This review aimed to evaluate studies that used specific load-measuring devices that could be mounted on an implant to measure the functional load in vivo.

Materials and methods

An electronic search utilizing the internet research databases PubMed, Google Scholar, and Scopus was performed. The articles were chosen by two authors based on the inclusion and exclusion criteria.

Results

In all, 132 studies were selected from the database search, and 16 were selected from a manual search. Twenty-three studies were finally included in this review after a complete full-text evaluation. Eleven studies were related to the force measurements using the strain gauges, and 12 were related to the piezoelectric force transducer. The principles of the two types of devices were completely different, but the devices produced comparable outcomes. The dynamics of the load magnitude and direction on the implant during function were clarified, although the number of participants in each study was small.

Conclusions

The load exerted on the implant during function was precisely measured in vivo using specific measuring devices, such as strain gauges or piezoelectric force transducers. The in vivo load data enable us to determine the actual biomechanical status in more detail, which might be useful for optimization of the implant prosthetic design and development of related materials. Due to the limited data and difficulty of in vivo measurements, the development of a new, simpler force measurement device and method might be necessary.

Influence of bone morphology on the mechanobiological stimuli distribution of maxillary anterior labial bone: A biomechanical study

OBJECTIVE

This study intended to ascertain the dimensional effects of labial bone thickness and height on the mechanobiological stimuli distribution of maxillary anterior labial bone through biomechanical analysis.

MATERIAL AND METHODS

Twelve 3D finite element models of an anterior maxillary region with an implant were computer-simulated, including four levels of labial bone thicknesses (2, 1.5, 1.0, and 0.5 mm) and three levels of labial bone heights (normal, reduced by 1/3, reduced by 1/2). A 45° buccolingual oblique load of 100 N was applied to the implant restoration.

RESULTS

Equivalent stress and principal strain mainly concentrated on crestal bone around the implant neck. The maximum equivalent stress in bone decreased as labial bone mass decreased, while the maximum principal strain and the displacement of dental implant increased as labial bone mass decreased. No significant difference of these three indicators was observed, when the labial bone thickness changed in the range of 2.0-1.0 mm with sufficient labial bone height.

CONCLUSIONS

In terms of biomechanics, the thickness of labial bone plate was recommended ≥1 mm. Sufficient labial bone height was warranted to prevent the stability of the implants from being seriously affected. The labial bone heights were more effective than thicknesses on the mechanobiological stimuli response of the dental implant-bone system.

CLINICAL SIGNIFICANCE

For this 3D finite element study, the biomechanical responses under different bone mass conditions were explored, in order to predict the process of bone remodeling and provide valid clinical recommendations for the decision-making process regarding the choices of tissue augmentation for some specific esthetic implantation cases for future clinical applications.

Etiology and Treatment of Peri-Implant Soft Tissue Dehiscences: A Narrative Review

Implant soft tissue dehiscences compromise not only the aesthetics of the supported restorations but implant survival in the long run. The aim of this narrative review was to briefly present the causative factors of buccal peri-implant soft tissue dehiscences (PSTDs), how these are classified, and the current therapeutic approaches. Implant malposition and the thin peri-implant phenotype are the two major determinants for the occurrence of PSTDs, but other risk factors have also been identified. The most common surgical procedure for treating PSTDs is the split-thickness coronally advanced flap combined with either a connective tissue graft or acellular dermal matrix materials. However, depending on the class and subtype of the dehiscence, the combination of surgical techniques with modifications in the restoration may further ameliorate the final result. In general, within a five-year follow-up period, most techniques lead to a satisfactory aesthetic result, although full coverage of the implant/abutment surface is not always achievable, especially in more extended lesions.

Accuracy of bone level assessments following reconstructive surgical treatment of experimental peri-implantitis

AIMS

The purpose was to evaluate the accuracy of bone level assessments using either cone beam computed tomography, intraoral periapical radiographs or histology following reconstructive treatment of experimental peri-implantitis.

MATERIALS AND METHODS

Six Labrador dogs were used. Experimental peri-implantitis was induced 3 months after implant placement. Surgical treatment of peri-implantitis was performed and peri-implant defects were allocated to one of four treatment categories; no augmentation, bone graft materials with or without a barrier membrane. Six months later, intraoral periapical radiographs and block biopsies from all implants sites were obtained. Marginal bone levels were measured using periapical radiographs, CBCT and histology.

RESULTS

Significant correlations of MBL assessments were observed between the three methods. The measurements in periapical radiographs consistently resulted in an overestimation of the bone level of about 0.3 - 0.4 mm. The agreement between methods was not influenced by the use of bone substitute materials in the management of the osseous defects.

CONCLUSIONS

Although MBL assessments obtained from PA radiographs showed an overestimation compared to MBL assessments on corresponding CBCT images and histological sections, PA radiographs can be considered a reliable technique for peri-implant bone level evaluations following reconstructive surgical therapy of experimental peri-implantitis.

Peri-implant soft tissue contour after stepwise replacement of missing and ankylotic central maxillary incisors in young adult: A clinical case report

Replantation and retention of ankylosed tooth after pubertal growth spurt enables stepwise replacement of both central incisors with implants. Partial extraction contributes to natural gingival contour.

Bone grafting history affects soft tissue healing following implant placement

BACKGROUND

This study aimed to determine and compare soft tissue healing outcomes following implant placement in grafted (GG) and non-grafted bone (NGG).

METHODS

Patients receiving single implant in a tooth-bound maxillary non-molar site were recruited. Clinical healing was documented. Volume and content of wound fluid (WF; at 3, 6, and 9 days) were compared with adjacent gingival crevicular fluid (GCF; at baseline, 1, and 4 months). Buccal flap blood perfusion recovery and changes in bone thickness were recorded. Linear mixed model regression analysis and generalized estimating equations with Bonferroni adjustments were conducted for repeated measures.

RESULTS

Twenty-five patients (49 ± 4 years; 13 males; nine NGG) completed the study. Soft tissue closure was slower in GG (P < 0.01). Differential response in WF/GCF protein concentrations was detected for ACTH (increased in GG only) and insulin, leptin, osteocalcin (decreased in NGG only) at day 6 (P ≤0.04), with no inter-group differences at any time(P > 0.05). Blood perfusion rate decreased immediately postoperatively (P < 0.01, GG) followed by 3-day hyperemia (P > 0.05 both groups). The recovery to baseline values was almost complete for NGG whereas GG stayed ischemic even at 4 months (P = 0.05). Buccal bone thickness changes were significant in GG sites (P ≤ 0.05).

CONCLUSION

History of bone grafting alters the clinical, physiological, and molecular healing response of overlying soft tissues after implant placement surgery.

Factors associated with the presence of peri-implant buccal soft tissue dehiscences: A case-control study

BACKGROUND

To identify factors associated with the presence of buccal soft tissue dehiscences (BSTD).

METHODS

This cross-sectional observational study assessed 52 cases (CAS) with a minimum of 24 months of loading, with the presence of a BSTD, defined as an exposure of the prosthetic abutment, the implant neck or the implant surface in the anterior maxillae or mandible (premolar-premolar) and 52 carefully selected controls (CON) matched for age and years in function, being the only difference between groups the BSTD. Clinical parameters and radiographic findings from periapical radiographs and Cone Beam Computed Tomographies (CBCT) were analyzed to assess their association with the occurrence of BSTD using a multivariate regression model.

RESULTS

The CAS had a mean keratinzed mucosa (KM) of 1.65 ± 1.31 mm, whereas in the CON KM was 3.27 ± 1.28 mm (P = 0.001). Probing depths were similar in both groups, whereas bleeding on probing and plaque scores were higher in the CAS (P = 0.001). Mean bone level scores in the CAS were 1.71 ± 1.04 mm, and 1.27 ± 1.01 mm in CON (P = 0.143). The first bone to implant contact at the buccal aspect was 4.85 ± 3.12 mm in CAS and 2.15 ± 3.44 mm in CON (P = 0.001). CAS were 1.48 ± 0.93 mm outside the alveolar envelope, whereas the CON were 0.46 ± 0.77 mm. Implants buccally positioned in the CBCT's were 34 times more likely to belong to the case group. The presence of >2 mm of KM at the time of evaluation, presence of adjacent natural teeth, cemented restorations and two-piece implants were protective factors.

CONCLUSION

The bucco-palatal implant position was the most relevant factor related to the presence of BSTD.

The influence of simultaneous lateral grafting on clinical outcomes following one-stage implant placement: a cross-sectional analysis

Background

To investigate the influence of lateral bone augmentation procedures performed simultaneously with implant placement on peri-implant health or disease.

Material and methods

A total of 232 patients showing the same type of a two-piece implant placed either simultaneously with lateral bone grafting using a bovine bone mineral and a native collagen membrane (n = 291 implants; test group) or at pristine bone sites without lateral bone grafting (n = 283 implants; control group) were enrolled in this cross-sectional analysis. Clinical outcomes (i.e., modified plaque index (mPI), bleeding on probing (BOP), probing depth (PD), and mucosal recession (MR)), and the frequency of peri-implant disease were evaluated after a mean follow-up period of 9.97 ± 6.55 years.

Results

No differences were found between the patients in the test and control groups for any of the parameters investigated (i.e., mPI, BOP, PD, and MR). For the implants in both groups, PD values of 4–6 mm were more frequently noted in the upper jaw. A significant correlation between increased PD values and a larger implant diameter was noted for test implant sites. A KM of < 2 mm was associated with increased MR values in both groups. The prevalence of peri-implant mucositis and peri-implantitis was 68% and 5% for the patients in the test group and 61% and 10% in the control group, respectively.

Conclusions

Simultaneous lateral grafting was associated with peri-implant tissue health and stability.

Long-term clinical and radiographic results after treatment or no treatment of small buccal bone dehiscences at posterior dental implants: A randomized, controlled clinical trial

AIM

To test whether or not buccal vertical bone dehiscences (≤5 mm) around posterior implants left for spontaneous healing (SH) result in the same clinical and radiologic outcome as dehiscences treated with guided bone regeneration (GBR) at 7.5 years after implant placement (IMPL).

MATERIALS AND METHODS

Twenty-two patients receiving 28 posterior implants with a small non-contained buccal bone dehiscence (≤5 mm) were randomly assigned to the SH or the GBR group. Implants were loaded at 6 months. Clinical parameters (probing depths, sulcus bleeding index, plaque index) and approximal marginal radiographic bone levels were assessed regularly up to at least 6.8 years. The vertical extension of the dehiscences was measured clinically at IMPL and abutment connection and radiographically on cone beam computed tomographys at a mean follow-up time of 7.5 years.

RESULTS

Twenty patients with a total of 26 implants were recalled at 7.5 years (9.1% dropout). The implant/crown survival rates were 100% in both groups. Stable peri-implant tissues were observed in both groups showing only minimal signs of inflammation. During the entire study period (IMPL-7.5-year follow-up), the median buccal vertical bone gain measured 1.61 mm for the GBR group and 0.62 for the SH group showing no significant difference between the groups. Also, at 7.5 years, the median approximal marginal bone levels (GBR: 0.53; SH: 0.68) were not significantly different between the two groups (p = .61) while the remaining median buccal vertical dehiscences were larger in the SH group (2.51 mm) compared to the GBR group (1.66 mm; p = .02).

CONCLUSIONS

Implants with small non-contained buccal bone dehiscences exhibited high implant survival rates and healthy peri-implant tissues at 7.5 years. In the GBR group, the buccal vertical bone levels were higher compared to the SH group but remained stable over the entire study period for both treatments.

Esthetic evaluation of single implant restorations, adjacent single implant restorations, and implant-supported fixed partial dentures: A 1-year prospective study

BACKGROUND

Peri-implant soft tissues esthetics varies and depends on the restoration type such as implant-supported single crowns, adjacent multiple single crowns, and fixed partial dentures (FPD).

PURPOSE

The aim of this prospective study was to assess the esthetic outcome of the peri-implant soft tissues of (NobelBiocare™) implant-supported single crowns, adjacent multiple single crowns, and FPD. A potential association between the esthetic risk profile and the esthetic outcome was assessed.

MATERIALS AND METHODS

Between 03/11 and 03/17, 300 NobelActive implants were installed in 153 partially edentulous patients. Prior to the fabrication of the final restoration, the esthetic risk profile (ERP) of the patient was determined. The pink esthetic score (PES) and white esthetic score (WES) were assessed by three investigators at 6 and 12 months post-insertion of the final restoration. Patients' appreciation was assessed on a visual analogue scale (VAS) at the 1-year follow-up.

RESULTS

The clinical acceptable limit for PES (≥6) was achieved in 56% to 68% of the single crowns at 6 and 12 months, respectively. Clinically unacceptable PES scores were recorded for 48% of the adjacent multiple single crowns and 63% of the FPDs at both time points. The association of a high ERP with WES and PESWES was noticed for single implant-supported crowns. For the latter restoration type, a ≤5 mm distance between the crestal bone level and the proximal contact positively influenced the PES and combined PESWES scores. No correlation was found between PES or WES and patient satisfaction. Mesial papilla formation was more pronounced compared to the distal one for the single implant crowns and for implant-supported FPD.

CONCLUSION

When high esthetic demands are expected, assessment of ERP prior to implant treatment is advised in order to estimate a realistic outcome.

Treatment of peri-implant soft tissue defects: a narrative review

Soft tissue defects around dental implants, such as papilla or volume loss, peri-implant recession and alterations of the ridge color and/or texture, lead to esthetic and functional complaints. Treatments of these defects in implants are more demanding than in teeth because peri-implant tissue exhibits different anatomical and histological characteristics. This narrative review discusses the proposed treatments for soft tissue defects around implants in the current literature. Several clinical and pre-clinical studies addressed methods to augment the quantity of the peri-implant keratinized mucosa. Autogenous grafts performed better than soft tissue substitutes in the treatment of soft tissue defects, but there is no clinical consensus on the more appropriate donor area for connective tissue grafts. Treatment for facial volume loss, alterations on the mucosa color or texture and shallow peri-implant recessions are more predictable than deep recessions and sites that present loss of papilla. Correction of peri-implant soft tissue defects may be challenging, especially in areas that exhibit larger defects and interproximal loss. Therefore, the regeneration of soft and hard tissues during implant treatment is important to prevent the occurrence of these alterations.

Therapeutic alternatives for addressing pink esthetic complications in single-tooth implants: A proposal for a clinical decision tree

OBJECTIVE

Esthetic complications in implant therapy today represent a clinical challenge, when the aim is to overcome the sequelae and obtain a pleasing result. The current scientific literature about this topic is scarce and often based on case reports and the personal opinions of clinicians.

CLINICAL CONSIDERATIONS

The aim of this article is to introduce a decision tree for diagnosis and treatment of complications, focusing on the pink esthetic of single-tooth implants and based on three diagnostic pillars (3D implant position, peri-implant hard-tissue anatomy, and peri-implant soft-tissue anatomy). Different shortcomings have been identified for each of the three diagnostic areas.

CONCLUSIONS

Following this tree, the article proposes treatment alternatives including soft- and hard-tissue reconstruction, implant submergence, orthodontic extrusion, and implant extraction in order to help clinicians establish a logical therapeutic sequence.

CLINICAL SIGNIFICANCE

Guidelines for adequate diagnosis and management of single implant-supported restorations with compromised esthetics is mandatory when attempt to overcome shortcoming in the pink esthetic result.

Ultrasonography for noninvasive and real-time evaluation of peri-implant tissue dimensions

AIM

Existing methods for evaluating marginal bone loss and tissue biotype around dental implants present with many limitations. The aim of this study was to examine the accuracy of high-resolution, 3-dimensional ultrasound to measure peri-implant tissue dimensions.

MATERIAL AND METHODS

A 25-MHz ultrasound probe prototype was used to scan peri-implant tissues of 17 implants from seven fresh human cadavers. Four ultrasonic measurements were made as follows: the marginal bone level/thickness, and mucosal level/thickness. The readings were statistically compared to cone beam computed tomography (CBCT) and/or open bone measurements.

RESULTS

The correlations (r) between the ultrasound and direct/CBCT readings of the four parameters ranged from 0.85 to 0.98 (p < 0.0001). The mean absolute difference in the four parameters between ultrasound-direct and ultrasound-CBCT ranged from 0.033 to 0.24 mm.

CONCLUSION

Encouraging evidence is shown that ultrasound can accurately measure peri-implant tissue dimensions. Following clinical trial validations, ultrasound offers potential as a valuable tool to evaluate long-term peri-implant tissue stability without concerns of ionizing radiation and image artefacts around implants.