Potential Bone to Implant Contact Area of Short Versus Standard Implants: An In Vitro Micro–Computed Tomography Analysis

A Nonlinear Three-Dimensional Finite Element Analysis of Stress Distribution and Microstrain Evaluation in Short Dental Implants with Three Different Implant-Abutment Connections in Single and Splinted Conditions in the Posterior Mandible

Background

Stress distribution plays a vital role in the longevity and success of implant-supported prosthesis. This study evaluated the von Mises stress and microstrain in the peri-implant bone and the implant-abutment junction of short dental implants with three different implant-abutment connections in splinted and unsplinted conditions using finite element analysis (FEA).

Materials and Methods

In this experimental study, nine transversely isotropic finite element models were developed, and randomly divided into three equal groups (n = 3): control, (Group AC) single-standard 4.3 × 10 mm bone level implant-supported restorations with external hexagonal (EH) connection, internal conical (IC) and internal trichannel (ITC) connection, single short implant-supported restorations (Group AT), and splinted short implant-supported restorations (Group B) for each of the three implant-abutment connections, respectively. A 200 N load was applied along the long axis of the implants and a 100 N (45°) oblique load was applied and von Mises stress and microstrain values were evaluated.

Results

Single standard implants demonstrated the highest von Mises stress and microstrain values followed by single short implants and splinted short implants, respectively. Among the implant-abutment connections, the IC connection showed the highest values and the ITC connection showed the least values.

Conclusion

Within the limitations of this study, it was concluded that splinting of short dental implants demonstrated lesser and more homogeneous stress and microstrain, especially on oblique loading. The microstrain values for all connections evaluated were within the physiological loading limit (200-2,500 N) and were hence considered safe for clinical use.

Short implants compared to regular dental implants after bone augmentation in the atrophic posterior mandible: umbrella review and meta-analysis of success outcomes

PURPOSE

To assess the body of evidence of short versus regular implants after bone augmentation (BA) in the atrophic posterior mandible in the context of implant treatment success outcomes.

METHODS

Seven databases, two registries, and reference lists were searched for systematic reviews and meta-analysis (SR/MA), randomized controlled trials (RCTs) and longitudinal studies published in English, Spanish or German since 2012. Confidence in the SR/MA methodology was evaluated using AMSTAR-2 and the risk of bias of primary studies using Cochrane's RoB 2.0 and ROBINS-I. A random-effects meta-analysis and a meta-regression were performed for continuous and dichotomous outcomes. GRADE approach was used to assess the certainty of the evidence.

RESULTS

Eighteen SRs/MAs, most of them "critically low" and "low" confidence with substantial overlap, included 14 relevant RCTs with a high risk of bias. A cohort study with moderate risk of bias was added. Quantitative synthesis of 595 implants and 281 hemiarches/patients indicates that the use of short implants (< 10 mm) compared to regular implants and BA may reduce implant failure at 1-year follow-up, and marginal bone loss (MBL) at 3-, 5-, and 8-year follow-up; is likely to reduce the risk of biological complications at 1-, 3-, 5-, and 8-year follow-up; and may be the patient's preferred alternative. There is a correlation between bone height, MBL and biological complications.

CONCLUSIONS

The available evidence partially suggests that the use of short implants could decrease implant failure, MBL, and biological complications, and increase patient satisfaction. However, given the need for further RCTs and real-world evidence to fully evaluate short- and long-term outcomes, it would be prudent for clinicians to carefully consider the individual needs and circumstances of the patients before deciding whether to use short implants. Trial registration PROSPERO CRD42022333526.

Epithelial Biological Response to Machined Titanium vs. PVD Zirconium-Coated Titanium: An In Vitro Study

The aim of this study was to compare the epithelial biological response to machined titanium Ti-6Al-4V grade 5 and titanium Ti-6Al-4V grade 5 coated with zirconia (ZrN) by physical vapor deposition (PVD). Human keratinocytes were cultured in six-well plates. Machined titanium TiAl4V4 grade 5 (T1) and ZrN-coated titanium TiAl4V4 grade 5 (T2) discs were placed in two different wells. The remaining two wells served as control (C). Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were performed to compare the T1 and T2 surfaces. Subsequent analyses were performed to explore the effect of T1 and T2 contact with human keratinocyte HUKE cell lines. Cell viability was evaluated using a trypan blue exclusion test and MTT assay. Cell lysates from C, T1, and T2 were Western blotted to evaluate E-cadherin and Integrin-α6β4 expression. SEM revealed that T2 was smoother and more homogeneous than T1. EDS showed homogeneous and uniform distribution of ZrN coating on T2. Cell viability analyses did not show significant differences between T1 and T2. Furthermore, E-cadherin and Integrin-α6β4 expressions of the epithelial cells cultured in T1 and T2 were similar. Therefore, titanium Ti-6Al-4V grade 5 surfaces coated with ZrN by PVD seem to be similar substrates to the uncoated surfaces for keratinocyte adhesion and proliferation.

Clinical comparison between crestal and subcrestal dental implants: A systematic review and meta-analysis

STATEMENT OF PROBLEM

How the performance of dental implants is related to their occlusogingival placement, crestal or subcrestal, is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate marginal bone loss, implant survival rate, and peri-implant soft tissue parameters between implants placed at the crestal and subcrestal bone level.

MATERIAL AND METHODS

Two independent reviewers searched the PubMed/MEDLINE, Embase, and Cochrane Library databases for randomized clinical trials published up to September 2020. The meta-analysis was based on the Mantel-Haenszel and the inverse variance methods (α=.05).

RESULTS

The search identified 928 references, and 10 studies met the eligibility criteria. A total of 393 participants received 709 implants, 351 at crestal bone levels and 358 at subcrestal bone levels. Meta-analysis indicated that crestal bone level implants showed similar marginal bone loss to that seen with subcrestal bone level implants (mm) (P=.79), independent of the subcrestal level (P=.05) and healing protocol (P=.24). The bone level implant placement did not affect the implant survival rate (P=.76), keratinized tissue (mm) (P=.91), probing depth (mm) (P=.70), or plaque index (%) (P=.92).

CONCLUSIONS

The evidence suggests that both approaches of implant placement are clinically acceptable in terms of peri-implant tissue parameters and implant-supported restoration survival.

Comparative Clinical Study Using Short and Conventional Implants in Bilateral Jaw Posteriors

The aim of this study was to clinically and radiographically compare extra short and standards implants. Forty-two implants were installed in 10 selected patients. They received prosthetic loading only after the conventional waiting time for osseointegration and the prostheses were made ferulized. Radiographic shots were performed to evaluate vertical and horizontal bone losses at times T1 (prosthetic installation), T2 (6 months follow-up) and T3 (12 months follow-up). Biological parameters such as bone level around the implants (CBL) were evaluated, CBL alteration (CBLC), total crown length (TCL) and implant/crown ratio (ICR) were digitally calculated. All implants included in the study were submitted to the analysis of the implant stability quotient (ISQ) at the time of implant installation (T0) and at 12 months of prosthetic function (T3). Data were statistically tested. The ICR was higher in the test group than in the control group (p<0.0001). The CBL measurements at the beginning of the study were 0.21±0.19 mm and 0.32±0.38 mm and at 12 months 0.65±0.24 mm and 0.87±0.34 mm, respectively in the test and control groups. CBLCs and CBL were similar at all times (p>0.05). No correlation was found between CBLC and ICR parameters, as well as between ISQ and implant length. We may conclude that standards and extra short implants can provide similar clinical results in prosthetic rehabilitation of the atrophic jaw over 12 months of follow-up.

Clinical Performance of Short Expandable Dental Implants for Oral Rehabilitation in Highly Atrophic Alveolar Bone: 3-year Results of a Prospective Single-Center Cohort Study

Background and Objectives: Oral health-related quality of life (OHRQOL) is compromised during the post-implant healing period, especially when vertical augmentation is required. A long-term trial sought to evaluate a short dental implant system with an apically expandable macro-design. Materials and Methods: Over 4.5 years, patients with limited vertical alveolar bone were consecutively recruited into this prospective cohort study. Implant success rate, OHRQOL (Oral Health Impact Profile (OHIP)-14), implant stability, and crestal bone changes were evaluated. Results: Data from 30 patients (mean age: 64.6 years, range 44–83) were analyzed, which related to 104 implants (53 in the maxilla, 51 in the mandible). Over the mean follow-up (42.6 ± 16.4 months), the implant success rate was 94.7% in the mandible (two implants lost) and 83.6% in the maxilla (four implants lost; p = 0.096), and the prosthetic success rate was 100%. The median OHIP-14 scores improved from 23 (interquartile range (IQR) 9–25.5) to 2 (IQR 0–5; p < 0.001). The mean implant stability quotient (ISQ) was 71.2 ± 10.6 for primary stability and 73.7 ± 13.3 (p = 0.213) for secondary stability, without significant maxilla-versus-mandible differences (p ≥ 0.066). Compared to the baseline, median crestal bone changes after loading were 1.0 mm (IQR 0–1.3) and 1.0 mm (IQR 0.2–1.2) in the maxilla and mandible (p = 0.508), respectively, at the end of the first year, 1.1 mm (IQR 0–1.3) and 1.0 mm (IQR 0.1–1.2) (p = 0.382), respectively, at the end of the second year, and 1.2 mm (IQR 0–1.9) and 1.1 mm (IQR 0.1–1.2) (p = 0.304), respectively, at the end of the third year. Conclusions: In patients with limited vertical bone height, short implants with optimized macro-design constitute a reliable method for functional rehabilitation, avoiding extensive alveolar bone augmentation.

Extra-short implants in the prosthetic rehabilitation of the posterior maxilla

AIM

To compare clinical outcomes of 'extra-short' and regular bone level implants in the posterior maxilla for 12 months after loading.

MATERIALS AND METHODS

Twenty-three systemically healthy, non-smoking patients received 30 extra-short, 24 regular bone level implants. Acrylic stents were fabricated for each patient for correct implant positioning. Implant lengths were 4-6 mm in the test, 8/10 mm in the control group. Radiographic evaluation was performed at baseline, 6, and 12 months after loading. Crestal bone level (CBL), CBL change (CBLC), true crown length (TCL), implant/crown ratio (ICR) and residual bone height (RBH) below maxillary sinus floor were calculated digitally. Data were tested statistically.

RESULTS

Residual bone height was significantly lower, and TCL and ICR were higher in the test than the control group (P < 0.0001). CBL measurements at baseline were 0.19 ± 0.18 mm and 0.31 ± 0.37 mm and at 12 months, 0.24 ± 0.24 mm and 0.41 ± 0.31 mm, respectively in the test and control groups. CBL values at 12 months were significantly lower in the test than the control group (P < 0.05). CBLCs were similar at all times (P > 0.05). No correlation was found between the CBLC and implant/prosthetic parameters.

CONCLUSION

Extra-short and regular implants might provide similar clinical outcomes in prosthetic rehabilitation of atrophic maxilla, during 12 months follow-up.

Novel expandable short dental implants in situations with reduced vertical bone height-technical note and first results

PURPOSE

Short implants often have the disadvantage of reduced primary stability. The present study was conducted to evaluate the feasibility and safety of a new expandable short dental implant system intended to increase primary stability.

METHODS

As a "proof of concept", a prospective clinical cohort study was designed to investigate intraoperative handling, primary and secondary implant stability (resonance frequency analysis), crestal bone changes, implant survival and implant success, of an innovative short expandable screw implant. From 2014 until 2015, 9 patients (7-9-mm vertical bone height) with 30 implants (length 5-7 mm, diameter 3.75-4.1 mm) were recruited consecutively.

RESULTS

All 30 implants in the 9 patients (age 44 to 80 years) could be inserted and expanded without intraoperative problems. Over the 3-year follow-up period, the implant success rate was 28/30 (93.3%). The mean implant stability quotients (ISQ) were as follows: primary stability, 69.7 ± 10.3 ISQ units, and secondary stability, 69.8 ± 10.2 ISQ units (p = 0.780), both without significant differences between the maxilla and mandible (p ≥ 0.780). The mean crestal bone changes after loading were (each measured from the baseline) as follows: in the first year, 1.0 ± 0.9 mm in the maxilla and 0.7 ± 0.4 mm in the mandible, and in the second year, 1.3 ± 0.8 mm and 1.0 ± 0.7 mm, respectively.

CONCLUSIONS

Compared to other prospective studies, in this indication, the success rate is acceptable. Implant stability shows high initial and secondary stability values. The system might present an extension of functional rehabilitation to the group of elderly patients with limited vertical bone height. Further long-term investigations should directly compare this compressive implant with standard short implants.