Bone Loss in Implants Placed at Subcrestal and Crestal Level: A Systematic Review and Meta-Analysis

Evaluation of Microstrain in the Regions Surrounding Morse Taper and External Hexagon Implants

OBJECTIVE

 The aim of this study was to compare the Morse taper (MT) + titanium base (Ti-Base) abutment with the external hexagon (EH) + Ti-Base abutment by using the strain gauge method in the mesial, distal, and apical-buccal areas around these types of implants.

MATERIALS AND METHODS

 This study investigated two groups, MT and EH, each comprising five polyurethane samples with a dental implant in the area of artificial tooth 15 (3.75 × 11.5 mm) of a dental manikin. The strain gauges were glued to the mesial, distal, and apical-buccal polyurethane areas of all samples in relation to the implant. Ti-Base nonangled abutments measuring 5.0 × 4.7 × 1.0 mm (DSP, Brazil) were installed on the implants in each group. Ten identical zirconia crowns were constructed by scanning and milling and were subsequently cemented onto the Ti-base abutments with calcium hydroxide cement. Then, an axial load of 100 N was applied to the occlusal region of the zirconia crowns, and strain gauge measurements were taken.

STATISTICAL ANALYSIS

 Strain gauge data were assessed by a two-way analysis of variance (ANOVA) with "implant connection" and "strain gauge position" factors, followed by the Bonferroni test (p < 0.05).

RESULTS

 The MT group exhibited a statistically significant reduction in microstrain in the mesial and apical strain gauge measurements compared to the EH group.

CONCLUSION

 The MT group exhibited less microstrain in the mesial and apical areas of the polyurethane samples near the implant. Consequently, the MT connection was considered more biomechanically advantageous.

Effect of vertical implant position on marginal bone loss: a randomized clinical trial

OBJECTIVES

One of the most important factors that has influence on dental implants success rate is marginal bone loss. The purpose of this study is to investigate the effect of the implant's vertical position and the soft tissue's thickness on the rate of marginal bone loss of the dental implant.

MATERIALS AND METHODS

In this single-blind randomized clinical trial study, 56 implants placed in the posterior region of mandible of 33 patients (19 women, 14 men) were divided into two groups. The group of crestal (28 implants) and subcrestal (28 implants) implants, each group was divided into two sub-groups with soft tissue thickness of 2 mm and less than 2 mm (14 implants) and more than 2 mm (14 implants). The amount of marginal bone loss was measured by Scanora 5.2 program with radiographs Digital parallelism based on the effect of the vertical position of the implant, soft tissue thickness, three months after placement, and three months after loading implants (six months after implant placement).

RESULTS

The results showed that marginal bone loss in subcrestal implants is significantly more than crestal implants (p-value = 0.001), and also marginal bone loss in the soft tissue thickness group of 2 mm and less is significantly more than the group of soft tissue thickness more than 2 mm (p-value < 0.001). The amount of marginal bone loss three months after implant loading was significantly higher than three months after implant placement (p-value < 0.001).

CONCLUSION

The implant's vertical position and the soft tissue's thickness around the implant are effective factors in the amount of marginal bone loss. Marginal bone loss is more in subcrestal implants and in cases with less soft tissue thickness. The time factor significantly affects the amount of marginal bone loss.

TRIAL REGISTRATION

this clinical trial was registered at Iranian Registry of Clinical Trials, registration number IRCT20120215009014N415, registration date 20,220,110, (https//en.irct.ir/trial/60,991).

Influence of torque and bone type on stability quotient of two implant platforms: a clinical trial

The objective of this study was to analyze the influence of insertion torque, bone type, and peri-implant bone loss on implant stability quotient (ISQ) of cylindrical external hexagon (EH) and Morse Taper (MT) implants. Forty-four single implants were placed in the edentulous areas of 20 patients who met the inclusion and exclusion criteria. Immediately after implant placement (t1) and after osseointegration (four and six months for mandible and maxilla, respectively) (t2), insertion torque, resonance frequency, and peri-implant bone loss were measured using probing depths and digital periapical radiography. A significant difference was noted in the ISQ values between t1 and t2 in type III bone for EH and MT implants. No significant difference in bone loss values was observed when comparing bone types for EH or MT in all evaluated sites. Based on marginal bone loss assessed using radiography, there was no significant difference between the MT and EH groups. A positive correlation between torque and ISQ t1 value was observed for MT (correlation: 0.439; p = 0.041) and EH (correlation: 0.461; p = 0.031) implants. For EH and MT implants, the greater the insertion torque, the greater was the ISQ value (moderately positive correlation). A weak negative correlation was found between bone type and ISQ t1 for MT implants. Contrarily, no correlation was observed between bone type and ISQ t1 for EH implants. In all cases, bone loss around the implants was clinically normal.

Clinical Peri-Implant Parameters and Marginal Bone Loss for Early Mandibular Implant Overdentures: A Follow-Up of 60 Months

Background and Objectives: Despite the identified benefits of early implant loading, studies have questioned its advantages compared to delayed loading in edentulous patients. This study aimed to evaluate clinical peri-implant parameters and marginal bone loss around early placed and loaded mandibular implant overdentures with a 60-month follow-up. Materials and Methods: In this prospective cohort study, 43 patients were enrolled to receive 86 early loading sub-crestal dental implants through prosthetic guides. Implant overdentures were supported by two isolated implant locator attachments between two mental foramens. Clinical peri-implant parameters, including plaque index (PI), bleeding index (BI), peri-implant pocket depth (PIPD), and marginal bone loss (MBL) were evaluated using standardized techniques at 1, 12, 24, 36, 48, and 60 months follow-up. At 60 months, complications associated with implant overdentures (IOD's) were noted. The mean comparison of peri-implant clinical parameters was performed through ANOVA test. A p-value of ≤0.05 was taken as significant. Results: Out of the total 43 enrolled patients, 8 patients were lost during follow-up; as a result, 35 patients completed the 5 years follow-up. The mean values of PI, BI, and PIPD increased with no statistical difference (p > 0.05). For marginal bone loss, an increase in the mean values was noted at different time intervals with statistical differences (p < 0.001). The most common complications noted were loosening of the abutment, occlusal adjustment, retentive locator loosening and replacement, and relining of the denture. Conclusions: Early placement of IODs failed to prevent bone loss over time and was associated with complications, predominantly consisting of abutment loosening, occlusal adjustments, broken retentive locator components, relining, and rebasing.

Conventional Versus Osseodensification Drilling in the Narrow Alveolar Ridge: A Prospective Randomized Controlled Trial

Background Conventionally, undersized osteotomies were used to increase initial bone-to-implant contact to achieve primary stability in implantology. This is particularly evident in regions with low bone density. The potential for severe bone compression and ischemia poses a challenge to secondary stability. Instead, lateral bone compaction is caused by the idea of osseodensification. Research on the potential benefits of this method for narrow ridges is lacking. This study aimed to determine if the osseodensification drilling technique affects primary stability and how much the alveolar ridge expands following implant site preparation. Methodology A total of 30 participants aged 20 to 80 years were included in this randomized controlled clinical investigation. Each participant was randomly assigned to one of the following two groups: one that received standard drill preparation, and another that received osseodensification drill preparation. Implant stability using implant stability quotient values, crest width, apical width (5 mm from crest), and bone density were assessed both before and after six months using cone-beam computed tomography. Results Osseodensification impacted the width at the apex (5 mm from the crest) and radiographic bone density, adding to the quality, but did not affect implant stability and crestal width after osseointegration. The mean difference in conventional and osseodensification groups was 0.46 and 0.68 mm, respectively, concerning the crestal width. Moreover, the mean difference was 0.74 and 0.58 mm for conventional and osseodensification groups, respectively, concerning the width at the apex (5 mm from the crest). Conclusions This study demonstrates that the osseodensification process increased both the radiographic bone density and the width at the apex, demonstrating that osseodensification drilling techniques allow for the placement of implants with larger diameters in narrow alveolar ridges.

Crestal and Subcrestal Placement of Morse Cone Implant-Abutment Connection Implants: An In Vitro Finite Element Analysis (FEA) Study

The issue of dental implant placement relative to the alveolar crest, whether in supracrestal, equicrestal, or subcrestal positions, remains highly controversial, leading to conflicting data in various studies. Three-dimensional (3D) Finite Element Analysis (FEA) can offer insights into the biomechanical aspects of dental implants and the surrounding bone. A 3D model of the jaw was generated using computed tomography (CT) scans, considering a cortical thickness of 1.5 mm. Subsequently, Morse cone implant-abutment connection implants were virtually positioned at the model's center, at equicrestal (0 mm) and subcrestal levels (-1 mm and -2 mm). The findings indicated the highest stress within the cortical bone around the equicrestally placed implant, the lowest stress in the -2 mm subcrestally placed implant, and intermediate stresses in the -1 mm subcrestally placed implant. In terms of clinical relevance, this study suggested that subcrestal placement of a Morse cone implant-abutment connection (ranging between -1 and -2 mm) could be recommended to reduce peri-implant bone resorption and achieve longer-term implant success.

Micro-CT Evaluation of Microgaps at Implant-Abutment Connection

The assessment of microgaps at the implant-abutment interface is an important factor that may influence clinical success. Thus, the aim of this study was to evaluate the size of microgaps between prefabricated and customised abutments (Astra Tech, Dentsply, York, PA, USA; Apollo Implants Components, Pabianice, Poland) mounted on a standard implant. The measurement of the microgap was performed using micro-computed tomography (MCT). Due to 15-degree rotation of samples, 24 microsections were obtained. Scans were performed at four levels established at the interface between the abutment and the implant neck. Moreover, the volume of the microgap was evaluated. The size of the microgap at all measured levels varied from 0.1 to 3.7 µm for Astra and from 0.1 to 4.9 µm for Apollo (p > 0.05). Moreover, 90% of the Astra specimens and 70% of the Apollo specimens did not exhibit any microgaps. The highest mean values of microgap size for both groups were detected at the lowest portion of the abutment (p > 0.05). Additionally, the average microgap volume was greater for Apollo than for Astra (p > 0.05). It can be concluded that most samples did not exhibit any microgaps. Furthermore, the linear and volumetric dimensions of microgaps observed at the interface between Apollo or Astra abutments and Astra implants were comparable. Additionally, all tested components presented microgaps (if any) that were clinically acceptable. However, the microgap size of the Apollo abutment was higher and more variable than that of the Astra one.

Exploring the Importance of Corticalization Occurring in Alveolar Bone Surrounding a Dental Implant

Several measures describing the transformation of trabecular bone to cortical bone on the basis of analysis of intraoral radiographs are known (including bone index or corticalization index, CI). At the same time, it has been noted that after functional loading of dental implants such transformations occur in the bone directly adjacent to the fixture. Intuitively, it seems that this is a process conducive to the long-term maintenance of dental implants and certainly necessary when immediate loading is applied. The authors examined the relationship of implant design features to marginal bone loss (MBL) and the intensity of corticalization over a 10-year period of functional loading. This study is a general description of the phenomenon of peri-implant bone corticalization and an attempt to interpret this phenomenon to achieve success of implant treatment in the long term. Corticalization significantly increased over the first 5-year functional loading (CI from 200 ± 146 initially to 282 ± 182, p < 0.001) and maintained a high level (CI = 261 ± 168) in the 10-year study relative to the reference bone (149 ± 178). MBL significantly increased throughout the follow-up period—5 years: 0.83 ± 1.26 mm (p < 0.001), 10 years: 1.48 ± 2.01 mm (p < 0.001). MBL and radiographic bone structure (CI) were evaluated in relation to intraosseous implant design features and prosthetic work performed. In the scope of the study, it can be concluded that the phenomenon of peri-implant jawbone corticalization seems an unfavorable condition for the future fate of bone-anchored implants, but it requires further research to fully explain the significance of this phenomenon.

Assessing Microleakage at 2 Different Implant-Healing Abutment Interfaces

OBJECTIVES

This study aimed to evaluate implants from different manufacturers and determine whether implant-healing abutment interface has a significant impact on implant seal.

METHODS

An air-injection pressure measurement test was performed on implants with either line-contact (modified TSIII [TSM] and Bone Level Tapered [BLT]) or partial face-contact (BlueDiamond [BD], SuperLine [SL], ISII, and UFII) interface design from 6 different manufacturers. Forty implants per implant type were analysed. Pressure data were evaluated with Kruskal-Wallis test and Dunn's post hoc analysis (statistical significance was set at P < .05).

RESULTS

BLT implants leaked when the mean pressure was increased to 199.9 kPa. The following implants showed mean leakage pressures of 182.9 (TSM), 157.4 (BD), 112.9 (SL), 101.8 (ISII), and 30.6 (UFII). There was a significant difference between line-contact and partial face-contact implants (P < .001).

CONCLUSIONS

The implant interface design has a significant impact on implant microbial leakage. Implants with a line-contact interface exhibited a higher resistance to leakage than those with partial face-contact.

Marginal bone loss around crestal or subcrestal dental implants: prospective clinical study

Objectives

The stability of crestal bone has been reported as a major factor in the success of dental implants. Implants can be placed in an equicrestal (crestal) or subcrestal position. The aim of this study was to evaluate the effect of implant depth placement on marginal bone loss.

Materials and Methods

The study was created in a split-mouth design. Immediately after implant surgery, digital parallel radiographs were prepared and levels of bone were measured where marginal bone loss and bone level changes occurred. These measurements were repeated at 3-month and 6-month follow-up periods.

Results

In this interventional study, 49 implants were evaluated in 18 patients. Primary bone height was not significant between the intervention and control groups in both mesial and distal aspects at 3 months and 6 months from the baseline. The mean marginal bone loss on the mesial side was 1.03 mm in the subcrestal group and 0.83 mm in the crestal group. In addition, mean marginal bone loss on the distal side was 0.88 mm and 0.81 mm in the subcrestal and crestal groups, respectively. Marginal bone loss was not significantly different between sexes, the maxilla or mandible, and in the anterior or posterior regions as well as between different lengths and diameters of implants.

Conclusion

Based on the results of this study, there was no significant difference in terms of marginal bone loss between crestal and subcrestal implants.

Marginal Bone Loss in Internal Conical Connection Implants Placed at the Crestal and Subcrestal Levels before Prosthetic Loading: A Randomized Clinical Study

The vertical position concerning the bone in which the implants are placed has been related as one of the factors causing marginal bone loss. The objective of this study was to evaluate the bone loss that occurs before prosthetic loading around tapered internal connection (CIC) implants placed at the crestal (C) and subcrestal (S) levels. Method: A randomized clinical trial (RCT) was carried out, with a sample size of 62 implants placed in 27 patients who underwent radiological controls on the day of placement, at one month, and at 4 months, and stability was measured by resonance frequency analysis (RFA) on three occasions. Results: Bone loss in implants C and S from the time of placement (T0) and the month after (T1) was not significant (p = 0.54) (C = 0.19 mm and S = 0.15 mm). The difference between one month (T1) and four months (T2) (C = 0.17 mm and S = 0.22 mm) was not significant either (p = 0.26). The difference between the day of placement (T0) and the third and last measurement (T2) was almost null (p = 0.94) (C = 0.35 mm and S = 0.36). The overall success rate of the implants was 97.8%. The stability of the implants measured with RFA went from 70.60 (T0) to 73.16 (T1) and 74.52 (T2). Conclusions: No significant differences were found in the bone loss for implants placed at the C and S levels. The millimeters of bone loss detected in both vertical positions did not have a significant impact on the stability of the implants.

Effects of insertion torque values on the marginal bone loss of dental implants installed in sheep mandibles

The aim of the present in vivo study was to analyze and compare the effects on the crestal bone healing of two different implant macrogeometries installed in fresh socket areas and in normal bone areas with different insertion torque values. Two implant macrogeometries were used in the present study, DuoCone implant (DC) and Maestro implant (MAE), forming four groups: group DCws, in which the implants were installed in healing bone (without a socket); group DCfs, in which the implants were installed in post-extraction areas (fresh sockets); group MAEws, in which the implants were installed in healing bone (without a socket); group MAEfs, in which the implants were installed in post-extraction areas (fresh sockets). After 30 and 90 days of implantations in the bilateral mandibles of 10 sheep, eighty implants were evaluated through digital X-ray images and histologic slices. The crestal bone position in relation to the implant platform shoulder was measured and compared. The measured insertion torque was 47.2 ± 4.69 Ncm for the DCws group, 43.4 ± 4.87 Ncm for the DCfs group, 29.3 ± 3.16 Ncm for the MAEws group, and 27.7 ± 4.41 Ncm for the MAEfs group. The radiographic mesio-distal and histological bucco-lingual analyses showed significantly greater vertical bone loss in the implants installed with high torque (DC groups) in comparison to the implants installed with a low torque (MAE groups) (p < 0.05), at both evaluation times. In general, low insertion torque values (Maestro implants) showed better results of MBL when compared to implants installed with higher torque values (Duo Cone implants). Moreover, our results showed that the implants installed in the sites without sockets showed a less MBL in comparison with the implants installed in sites of fresh sockets.

Factors Influencing Marginal Bone Loss around Dental Implants: A Narrative Review

Implant supported dental prostheses are increasingly used in dental practice. The aim of this narrative review is to present the influence of transmucosal surface of prosthetic abutment and implant on peri-implant tissue. The article describes causes of bone loss around the dental implant. Moreover, properties of different materials are compared and discussed. The advantages, disadvantages, and biomechanical concept of different implant-abutment connections are presented. The location of connections in relation to the bone level and the influence of microgap between the abutment and implant are described. Additionally, the implant abutments for cemented and screwed prosthetic restorations are compared. The influence of implant and abutment surface at the transmucosal level on peri-implant soft tissue is discussed. Finally, the biological aspect of abutment-implant connection is analyzed.

Outcomes of alveolar segmental 'sandwich' osteotomy with interpositional particulate allograft for severe vertical defects in the anterior maxilla and mandible

The purpose of this study was to report the outcomes of interpositional osteotomy with mineralized allograft in the treatment of alveolar vertical defects in preparation for implant placement. Thirteen defects (11 maxillary and two mandibular) were treated with osteotomy segments ranging in length from two to five missing teeth. The segments were positioned 5-7 mm coronally, with the gap space filled with allograft and then fixated with titanium hardware. Vertical bone augmentation was analyzed by superimposing pre- and post-surgical cone beam computed tomography images and stratified based on the length and number of missing teeth in each edentulous segment. The mean vertical bone gain was 3.7 ± 1.6 mm in the area of greatest vertical defect and the mean length of the transport segment was 20.5 ± 8.1 mm. These segments represented two-, three-, four-, or five-tooth edentulous sites; the mean vertical bone gain for these segments was 1.7 ± 0.5 mm, 3.8 ± 1.0 mm, 4.6 ± 0.9 mm, and 6.7 ± 0.0 mm, respectively. Stability of vertical height gain was found to be directly proportional to the span length of the osteotomy segment, with the largest five-tooth segment achieving the greatest gain. Vertical bone gain in two-tooth segments was minimal, indicating a moderate amount of resorption.

One-Piece Titanium Implants: Retrospective Case Series

Purpose

One-piece titanium implants are not routinely used for reconstruction after tooth loss. Several limitations seemed to be apparent although the concept provides a straightforward approach for different clinical situations. A clinical documentation of five prosthetic restorations with one-piece titanium implants serving as a relevant treatment option in dental surgery is pursued. We demonstrate the feasibility and benefits of one-piece titanium implants for fixed dental prosthesis. Detailed descriptions of the technical features and the surgical approach by means of clinical cases are given. The prosthetic workflow when working with one-piece titanium implants is depicted in detail as well as examples for implant-supported tooth replacement in the posterior region and the esthetic zone. Conditions of applications regarding different timing of implant placement using the system and its limitations are discussed.

Results

Clinical cases with a follow-up period of up to 10 years are presented to prove the long-term success of one-piece titanium implants in terms of bone and soft-tissue stability respecting the biological criteria for periodontal health.

Conclusions

One-piece titanium implants represent a reliable treatment method for single-tooth replacements. Clinical success with long-time bone stability around the implantation site can be achieved. Taken into account the requirements for periodontal tissue stability, uneventful healing without extensive tissue loss is demonstrated by means of clinical cases presenting patients with periodontitis.

Biological Oriented Immediate Loading: A New Mathematical Implant Vertical Insertion Protocol, Five-Year Follow-Up Study

One of the current major challenges in implant therapy is to minimize marginal bone loss around implants, since it can trigger bacterial colonization of the implant’s neck, leading to its failure. The present study aimed (1) to scientifically validate a new mathematical rule based on soft tissues thickness, for choosing the correct implant position with respect to the bone level, in order to provide a better tissue adaptation to the abutment/implant surface to avoid bacterial invasion, and (2) to apply this mathematical rule to the Biological Oriented Immediate Loading (B.O.I.L.) surgical protocol, avoiding peri-implant bone resorption. N. 127 implants were inserted following B.O.I.L. protocol: implants were placed according to the mathematical rule Y = X − 3, which correlates the position of the implant from the bone crest level (Y) with the thickness of the soft tissues (X). All the implants were inserted in fresh extraction sockets, and immediately loaded with temporary abutments and prostheses. Bone levels were evaluated through radiographic examination just after surgical procedure (T0), and after 10 days (10D), 6 months (6M), 1 year (1Y), and 5 years (5Y). After 5 years, the implant survival rate was 100%, with a medium marginal bone loss around implants of 0.0704 mm (SD = 0.169 mm). One-way ANOVA, followed by Tukey’s multiple comparison test was performed for statistical evaluations (p < 0.05). This protocol provided a safe and successful procedure, with a good soft tissue seal against bacterial challenge. The application of the mathematical rule allows the implant placement in a correct vertical position from the bone crest, avoiding bone resorption and bacterial infiltrations. Moreover, the use of Multi Unit Abutment (MUA) determined a stable biological seal, favouring the implant healing and preserving the adhesion of hemidesmosomes to the titanium of MUA.

Biomechanical Evaluation of Stress Distribution in Subcrestal Placed Platform-switched Short Dental Implants in D4 Bone: In Vitro Finiteelement Model Study

The present study was carried out to assess stress distribution in the maxillary posterior bone region (D4 bone) with the help of a short platform switched subcrestal dental implants using the FEM model. Missing teeth surfaces related to the maxillary posterior region were stimulated. The bone model had a cancellous core of (0.5 mm) which represents D4 bone. A 7.5x4.6 mm screw type implant system with 3.5 platform switch abutment was selected. ANSYS WORKBENCH was used to model all the finite element structures. Force of 100 N was tested and adapted at an angle of 0º, 15º, 30º on the tooth model. Overall results from the current study showed that a high amount of stress was seen in cortical than in relation to cancellous bone. Stress values reduced from equicrestal to subcrestal (2 mm) placement of dental implants irrespective of angulation of load from 0o to 30o in both types of bone. However higher stress values were seen when force was applied in an oblique direction (30o) in comparison to a vertical load (0o). Least amount of stress was noticed when platform switched implants were placed 0.5 mm subcrestatlly irrespective of angulations of a load. Platform switched short subcrestal implants reduced the stress in the D4 cortical bone than in contrary equicrestal implant placement. This results in the preservation of marginal bone leading to implant success.

Marginal Bone Loss in Implants with External Connection versus Internal Conical Connection Prior to Prosthetic Loading. A Randomized Clinical Study

Introduction: The prosthetic connection of implants has been related to the loss of marginal bone. The aim of this study was to evaluate bone loss around external connection (EC) and internal conical connection (ICC) implants prior to prosthetic loading. Material and methods: A randomized clinical trial (RCT) was carried out, with a sample size of 93 implants (31 EC and 62 ICC) placed in 27 patients. Radiological controls were performed and stability was measured by resonance frequency analysis (RFA) on the day of placement, at 1 month and at 4 months after the placement. Results: Bone loss in EC implants was not statistically different than in ICC implants between the time of placement (T0) and the subsequent month (T1): (EC = 0.18 mm and ICC = 0.17 mm). Between one month (T1) and four months (T2): (EC = 0.39 mm and ICC = 0.19 mm) this difference was highly significant (p = 0.00). Bone loss between T0 and T2 was significantly lower in the ICC (EC = 0.57 mm and ICC = 0.36 mm), (p = 0.01). The overall success rate of the implants was 97.8%. The stability of the implants increased from 70.69 (T0) to 73.91 (T1) and 75.32 (T2). Conclusions: ICC showed less bone loss up to the time of prosthesis placement. Such bone loss did not have a significant impact on bone stability. Long term RCTs are needed to demonstrate whether this bone loss, which is more pronounced at the beginning in EC, tends to stabilize and equate to ICC.

The Long-Term Effect of Adapting the Vertical Position of Implants on Peri-Implant Health: A 5-Year Intra-Subject Comparison in the Edentulous Mandible Including Oral Health-Related Quality of Life

Despite high success rates of dental implants, surface exposure may occur as a consequence of biologic width establishment associated with surgery. This prospective split-mouth study evaluated the effect of early implant surface exposure caused by initial bone remodeling on long-term peri-implant bone stability and peri-implant health. Additionally, Oral Health-Related Quality of Life (OHRQoL) was assessed by means of the Oral Health Impact Profile-14 (OHIP-14). Twenty-six patients received two non-splinted implants supporting an overdenture in the mandible by means of locators. One implant was installed equicrestally (control) and the second one was installed subcrestally, taking at least 3 mm soft tissue thickness into account (test). During initial bone remodeling (up to 6 months postoperatively), equicrestal placement yielded 0.68 mm additional surface exposure compared to subcrestal placement (p < 0.001). Afterwards, bone level and peri-implant health were comparable in both treatment conditions and stable up to 5 years. The implant overdenture improved OHRQoL (p < 0.01) and remained unchanged thereafter (p = 0.51). In conclusion, adapting the vertical position of the implant concerning the soft tissue thickness prevents early implant surface exposure caused by initial bone remodeling, but in a well-maintained population, this has no impact on long-term prognosis. The treatment of edentulousness with an implant mandibular overdenture improves OHRQoL.

Radiological Outcomes of Bone-Level and Tissue-Level Dental Implants: Systematic Review

Background: to assess the radiological marginal bone loss between bone-level or tissue-level dental implants through a systematic review of literature until September 2019. Methods: MEDLINE, Embase and other database were searched by two independent authors including only English articles. Results: The search provided 1028 records and, after removing the duplicates through titles and abstracts screening, 45 full-text articles were assessed for eligibility. For qualitative analysis 20 articles were included, 17 articles of them for quantitative analysis counting a total of 1161 patients (mean age 54.4 years) and 2933 implants, 1427 inserted at Tissue-level (TL) and 1506 inserted at Bone-level (BL). The survival rate and the success rate were more than 90%, except for 2 studies with a success rate of 88% and 86.2%. No studies reported any differences between groups in term of success and survival rates. Three studies showed that BL-implants had statistically less marginal bone loss (p < 0.05). Only one study reported statistically less marginal bone loss in TL-implants (p < 0.05). Conclusion: In the most part of the studies, differences between implant types in marginal bone loss were not statistically significant after a variable period of follow-up ranged between 1 and 5 years.

The biological width around implant

PURPOSE

The concept of biological width has been proposed and widely used in oral implantation. This review aimed to summarize the biological width around implant in detail.

STUDY SELECTION

An electronic search of the literature prior to March 2019 was performed to identify all articles related to biological width in periimplant soft tissue. The search was conducted in the MEDLINE (National Library of Medicine) database accessed through PubMed with no date restriction. The following main keywords were used: "implant", "biological width", "soft tissue", "junctional epithelium", "peri-implant epithelium", "connective tissue", "gingiva", "mucosa" (connecting multiple keywords with AND, OR).

RESULTS

The identified researches focused on several aspects related to biological width in oral implantation, namely the concept, formation, remodeling, dimension, structure and function.

CONCLUSIONS

Based on of the reviewed literature, the concept, formation, remodeling, structure, dimension, and functional significances of periimplant biological width are explored in this narrative review. The formation of biological width around implant is a complex process after several weeks of healing. The biological width around implant is a 3-4mm distance from the top of the peri-implant mucosa to the first bone-to-implant contact or the stabilized top of the adjacent bone, consisting of sulcular epithelium, junctional epithelium and fibrous connective tissue between the epithelium and the first bone-to-implant contact or the stabilized top of the adjacent bone. The biological width forms a biological barrier against the bacteria, influences the remodeling of soft and hard tissue around implant and has implications for clinical aspects of dental implantation.

Five Degree Internal Conical Connection and Marginal Bone Stability around Subcrestal Implants: A Retrospective Analysis

BACKGROUND

There is limited information on the effect of the connection between subcrestally placed implants and abutments on marginal bone levels. The aim of the present retrospective study was to evaluate marginal bone levels after definitive prosthesis delivery around implants with an internal 5° conical connection placed in a subcrestal position.

MATERIALS AND METHODS

Patients treated with fixed prostheses supported by implants placed at a subcrestal level between 2012 and 2018 were recalled for a follow-up examination. All implants had 5° internal conical connection with platform switching. Radiographic marginal bone level (MBL) was measured. MBL change between prosthetic delivery (t₀) and follow-up examination (t₁) was calculated. A multiple regression model was performed to identify the most significant predictors on MBL change.

RESULTS

Ninety-three patients and 410 implants, with a mean follow-up of 2.72 ± 1.31 years, were examined. Mean MBL was -1.09 ± 0.65 mm and -1.00 ± 0.37 mm at t₀ and t₁, respectively, with a mean bone remodeling of 0.09 ± 0.68 mm. An implant's vertical position in relation to the bone crest, the year of follow up and the presence of type-2 controlled diabetes were demonstrated to be influencing factors for MBL modifications.

CONCLUSIONS

Subcrestally placed implants with platform switching and internal conical connection maintained stable bone levels over a mean follow-up of more than 2 years. How a tight internal conical connection between abutment and implant may contribute to this clinical evidence should be more deeply investigated. MBL variations seem to be mostly influenced by an implant's vertical position and presence of type-2 controlled diabetes.

Long-Term Clinical Outcomes of Treatment with Dental Implants with Acid Etched Surface

Implant dentistry constitutes a therapeutic modality in the prosthodontic treatment of partially and totally edentulous patients. This study reports a long-term evaluation of treatment by the early loading of acid-etched surface implants. Forty-eight partially and totally edentulous patients were treated with 169 TSA Defcon® acid-etched surface implants for prosthodontic rehabilitation. Implants were loaded after a healing free-loading period of 6–8 weeks in mandible and maxilla, respectively. Implant and prosthodontic clinical findings were followed during at least 17 years. Clinical results indicate a survival and success rate of implants of 92.9%, demonstrating that acid-etched surface achieves and maintains successful osseointegration. Five implants in three patients were lost during the healing period. Sixty-five prostheses were placed in 45 patients over the remaining 164 implants, 30 single crowns, 21 partially fixed bridges, 9 overdentures, and 5 full-arch fixed rehabilitations. A total of 12 implants were lost during the follow-up period. Mean marginal bone loss was 1.91 ± 1.24 mm, ranging from 1.1 to 3.6 mm. The most frequent complication was prosthetic technical complications (14.2%), followed by peri-implantitis (10.6%). The mean follow-up was of 214.4 months (208–228 months). Prosthodontic rehabilitation with an early-loading protocol over acid-etched surface implants is a successful implant treatment.