Retrospective study on the clinical and radiographic outcomes of 2.8 mm diameter implants supporting fixed prostheses up to 11 years

OBJECTIVES

This study aimed to report the clinical and radiographic results of 2.8 mm two-piece narrow diameter implant (NDI) supporting fixed restorations.

MATERIALS AND METHODS

Clinical and radiographic data of 54 NDIs in 32 patients were retrospectively assessed after 2 to 11 (mean 8.17) years of follow-up. Clinical and radiographic measurements were taken. Survival rate, implant and prosthesis failure, pink aesthetic scores (PES), white aesthetic scores (WES), bleeding on probing (BOP), probing depth (PD), marginal bone loss (MBL), and mechanical and biological complications were evaluated.

RESULTS

An implant failed during the follow-up period, resulting in a cumulative survival rate of 98.15% at the implant level and 96.88% in the patient. The total mean values of PES and WES for 2.8 mm NDIs were 7.09 ± 1.15 (range: 3.33-9.00) and 7.42 ± 1.03 (range: 3.67-9.33). The prevalence of sites with positive BOP was 38.14 ± 29.77%. The mean PD value was 2.46 ± 0.62 mm. The average MBL was 1.15 ± 0.74 mm (range: 0.25-4.03 mm). No implant or abutment fracture was detected. A veneer chipping was present in one patient, and a loose crown appeared in another patient. Two implants (3.7%) and two patients (6.3%) were diagnosed with peri-implantitis.

CONCLUSION

Within the limitation of the study, the results indicate that the use of two-piece 2.8 mm NDI for the fixed prosthetic rehabilitation of edentulous regions with reduced interdental and/or buccal-lingual width is viable.

The Effect of Implant-Associated Factors on the Long-Term Outcomes of Dental Implants

The long-term outcomes of dental implants are influenced by a variety of factors, all of which play critical roles in their stability, functionality, and esthetic appeal. This review focuses on several key characteristics of dental implants that impact their success overtime: dimensional, morphologic, material, osseointegrative, and connective/prosthetic characteristics. This article synthesizes current literature to analyze how these factors influence the long-term success of dental implants, emphasizing the need for a comprehensive approach in implant selection and placement.

Use of narrow-diameter implants in the posterior segments of the jaws: A retrospective observational study of 2 to 11 years

STATEMENT OF PROBLEM

The placement of narrow-diameter implants (NDIs) in the posterior region is still debated in view of the high biomechanical risks in these areas.

PURPOSE

The purpose of this retrospective observational study was to evaluate the success and survival rates of NDIs restored with fixed prostheses in the posterior region (primary outcome) and analyze whether splinting multiple units (prosthesis design) affects the biological and mechanical complications (secondary outcome).

MATERIAL AND METHODS

Dental records from 2 private clinics were reviewed for NDIs in the posterior region installed between 2009 and 2018. Ninety study participants (58 women and 32 men) aged between 21 and 84 years (mean age 49.9 years) were recalled for the assessment of implant survival and success of 160 NDIs previously provided for partial posterior edentulism associated with moderate horizontal bone loss or reduced interradicular space (105 premolars and 55 molars). The implants were restored with metal-ceramic single crowns or splinted multiple-unit prostheses, either screw-retained or cemented on custom (n=100) or stock titanium abutments (n=60). Peri-implant probing depth (PPD), bleeding on probing (BOP), bone quality, type of edentulism, and patient satisfaction were scored. The chi-squared test for independence and 2-sample Welch t test were performed for statistical analysis (α=.05).

RESULTS

The overall success rate was 89.37%. One implant had been removed 4 years after loading, another after 9 years, yielding a cumulative survival rate of 98.75%. Fourteen implants exhibited PPD > 5 mm. One implant and 1 abutment screw fractured, and 16 restorations demonstrated porcelain chipping. The chi-squared test showed no significant relationship between prosthetic design and complications whether biological (P=.087) or mechanical (P=.805). Eighty-two percent of patients were satisfied with esthetics, 76% with function, 85% with total duration of treatment, and 90% with overall treatment cost.

CONCLUSIONS

Within the limitations of this retrospective study, NDIs may be considered a reliable option to replace posterior teeth. The prosthetic design had no significant impact on biological or mechanical complications.

Effects of cyclic loading on loss of abutment screw torque of angled screw channel single implant crowns on narrow diameter implants

STATEMENT OF PROBLEM

Screw access channels that emerge on the facial aspect of anterior screw-retained implant crowns can compromise esthetics. Recently, angled screw channels (ASCs) have been developed that can alter screw access channel angulations to improve esthetics. While ASCs can be used on narrow-diameter implants, information is limited on the loss of abutment screw torque on narrow-diameter implants with ASCs.

PURPOSE

The purpose of this in vitro study was to compare the loss of abutment screw torque after thermocycling and the cyclic loading of ASCs from 3 different companies connected to narrow-diameter implants.

MATERIAL AND METHODS

A total of 40 narrow-diameter implants (NobelReplace Conical Connection 3.5×11.5 mm) were mounted individually in acrylic resin blocks and divided equally into 4 groups. The first group, NB-0 (Control), consisted of screw-retained zirconia crowns fabricated on ASCs at 0-degree angulation (n=10). The other 3 groups consisted of a total of 30 screw-retained zirconia crowns fabricated on ASCs at 20-degree angulation: NB-20 (Angulated Screw Channel Solutions), ATL-20 (Atlantis Custom Base Solution with angulated screw access), and DA-20 (Dynamic TiBase). Each crown was secured on the mounted implant with its corresponding titanium base insert and screw and then tightened to the manufacturer's recommended torque with a digital torque gauge. The initial reverse torque value (RTVI) was obtained and recorded at baseline. Subsequently, a new set of screws were tightened to recommended values, and each specimen underwent thermocycling and then cyclic loading at 0 to 100 N at 10 Hz for 1 million cycles to simulate 1year of functional loading. After cyclic loading, the final reverse torque values (RTVF) were recorded and compared with the RTVI to evaluate the percentage torque loss (PTLF). Statistical analysis was performed using the Kruskal-Wallis analysis, Rank base analysis of covariance (ANCOVA), and the Tukey HSD post hoc comparisons (α=.05).

RESULTS

Significant differences were found for the PTLF among all groups after cyclic loading (P<.001). The PTLF in ATL-20 (51.4%) was significantly higher than in NB-0 (22.2%) (P<.001) and NB-20 (29.2%) (P=.010). No significant difference was found in the PTLF among other groups (P>.05).

CONCLUSIONS

The abutment screw torque loss after cyclic loading of the ASCs on narrow diameter implants among the 4 groups did not perform comparably. The largest percentage torque loss was recorded for the ATL-20 group. The NB-20 group demonstrated the lowest percentage torque loss. DA-20 showed percentage torque loss less than ATL-20; however, its RTVF was the lowest.

Evaluation of the clinical safety and performance of a narrow diameter (2.9 mm) bone-level implant: a 1-year prospective single-arm multicenter study

PURPOSE

Narrow-diameter implants facilitate single-tooth restoration when interdental or inter-implant spaces and bone volume are inadequate for using standard diameter implants. This study reports the short-term data on the clinical safety and performance of a bone-level-tapered two-piece implant with a 2.9 mm diameter in the clinical practice setting. This study was retrospectively registered on March 1st, 2016 (NCT02699866).

METHODS

Implants were placed in partially healed extraction sockets of the central and lateral incisors in the mandible and lateral incisors in the maxilla for single-tooth replacement. The primary outcome was to assess implant survival at 12 months after placement. Secondary outcomes included implant success, pink esthetic score, marginal bone-level changes, and safety.

RESULTS

Twenty four males and 17 females with a mean age of 44.5 (± 18.3 standard deviation) received the implant. Three out of 41 implants were lost yielding a survival rate of 92.7% (95%-CI: 79.0%; 97.6%) at 1 year. One patient reported an ongoing foreign body sensation, pain, and/or dysesthesia at month 12. The average pink esthetic score at 6 months was 11.2 (95%-CI: 10.5; 11.9). The bone level was stable with a mean bone-level change of-0.3 mm (± 0.42 mm standard deviation) at 1 year after implantation. No serious adverse events or adverse device events were reported.

CONCLUSIONS

The use of a 2.9 mm diameter bone-level-tapered implant is a safe and reliable treatment option for narrow tooth gaps at the indicated locations. Overall performance and good survival rates support their use in cases, where wider implants are unsuitable.

Bone-Regenerative Ability of Platelet-Rich Plasma Following Sinus Augmentation with Anorganic Bovine Bone: A Systematic Review with Meta-Analysis

BACKGROUND

The objective of this systematic review is to assess the effect of the adjuvant use of platelet-rich plasma (PRP) and its type on new bone formation by anorganic bovine bone during maxillary sinus floor augmentation procedure.

METHODS

PubMed, Cochrane Central Register of Controlled Trials, and Ovid databases were searched for relevant studies published up to 16 September 2021. Randomized clinical trials (RCTs) and non-randomized controlled clinical trials (CCTs) that reported data on the new bone formation (measured by histomorphometric analysis) were considered. Risk of bias and quality assessment of included studies were evaluated following the Cochrane Handbook for Systematic Reviews of Interventions and the Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) tool. Strength of evidence was assessed following the approach of the Agency for Healthcare Research and Quality (AHRQ) through its evidence-based practice center (AHRQ EPC). The meta-analysis was based on the primary outcome of newly formed bone, for which the standard mean difference was calculated.

RESULTS

After the application of eligibility criteria, six clinical trials (three RCTs and three CCTs) covering 85 maxillary sinus floor elevation procedures were included. The pooled new bone formation value for PRP was 1.67 (95% CI: -0.15 to 3.49; I2: 86%), indicating the absence of significant effect. Plasma rich in growth factors (PRGF) was the pure PRP tested in five of the included studies. When sub-group (type of PRP) meta-analysis was performed, significantly higher new bone formation was observed in the PRGF group [2.85 (95% CI: 0.07 to 5.64; I2: 88%)] in comparison to the control group.

CONCLUSIONS

A beneficial effect on new bone formation after maxillary sinus floor elevation can be obtained when anorganic bovine bone is mixed with PRGF.

Short Narrow Dental Implants versus Long Narrow Dental Implants in Fixed Prostheses: A Prospective Clinical Study

There is a paucity of studies that assess short and narrow dental implants. This prospective study aimed to evaluate the performance of both short (≤8 mm) and narrow (≤3.5 mm width) dental implants supporting fixed prostheses in the atrophic maxilla or mandible. Towards that aim, patients with short implants were included in the study. The control group was those with long and narrow dental implants (length > 8 mm and diameter ≤ 3.5 mm). Clinical and demographic variables were extracted from clinical records. During the follow-up, implant survival and marginal bone loss were evaluated and statistically analysed. Forty-one implants were included (18 and 23 implants in the test and control groups, respectively). The median follow-up time was 26 months since insertion in both groups. The results revealed that there was no implant failure and no statistically significant differences in terms of marginal bone loss. Only one screw-loosening effect occurred in the short implants group. Short, narrow dental implants could be an alternative for the restoration of severely resorbed jaws.

Implant-prosthetic rehabilitation of patients with severe horizontal bone deficit on mini-implants with two-piece design-retrospective analysis after a mean follow-up of 5 years

BACKGROUND

As a consequence of tooth loss due to trauma or extraction, a reduced alveolar crest volume limits the deployment of standard implants in certain patient cases. For this reason, minimal-invasive treatment with mini-dental implants (MDI) might be an option to allow implant treatment even in cases with severe horizontal bone loss without augmentation measures. The aim of this retrospective cohort study was to investigate clinical and radiological implant, as well as patient-related parameters after treatment with MDI.

RESULTS

Clinical and radiological records of 19 female (82.6%) and 4 male patients (17.4%) (N = 23), who received 52 mini-dental implants with a two-piece design in a single surgical center between November 2011 and October 2018, were retrospectively analyzed. Implants were submitted to conventional loading on different types of screwed superstructures. Crestal bone loss was measured on standardized periapical radiographs. Patient-related outcome parameters (PROMs) were recorded during follow-up period. Mean clinical and radiological follow-up was 69.6 months (5.8 years) and 51.6 months (4.3 years), respectively. Three implants were lost in two patients, leading to an implant survival rate of 94.2%. Mean radiological crestal bone loss was 1.6 mm. Both amount of peri-implant recession and crestal bone loss were significantly correlated (r = 0.65; p < 0.001). Likewise, a significant correlation was observed between deeper probing depths and increased peri-implant bone loss (r = 0.41; p = 0.012). Alveolar ridges with a reduced alveolar crest width were significantly correlated with higher peri-implant bone loss as well (r = - 0.33; p = 0.011). No prosthetic complications were reported during follow-up. Extent of midfacial recession and papilla height loss had a significant negative impact on most of the PROMs.

CONCLUSIONS

Treatment with MDI seems to be a successful alternative treatment option, especially for elderly patients with reduced crest width at implant sites. Due to the good clinical results and high survival and success rates, this treatment option was associated with high patient satisfaction. Despite the promising results, particular consideration should be given to appropriate treatment planning in these patients due to the strong correlation between peri-implant soft-tissue parameters, crestal bone loss, and reduced alveolar crest width.

Implant-prosthetic treatment in patients with oral lichen planus: A systematic review

AIMS

This review is aiming on identifying the ideal implant-prosthetic treatment design in patients with OLP.

METHODS AND RESULTS

A systematic review was conducted using four electronic databases; Medline (PubMed), Cochrane library, DOAJ and SCOPUS, following the PRISMA statement recommendations to answer the PICO question: "which implant-prosthetic treatment design is most useful to ensure implant survival in OLP patients?". The study was pre-registered in PROSPERO (CRD 42020220102). Included articles quality was assessed using the "Newcastle-Ottawa scale" and the JBI critical appraisal tool for case series. No article was found specifically designed to analyze the prosthetic influence on implant survival in OLP patients. Despite, information about implant-prostheses in studies designed with other goals was compiled. Eight articles that involved 141 patients and 341 implants were finally selected. The weighted mean follow-up was 38 months and the weighted mean survival of the implants 98.9%. No statistical differences were observed between cemented or screw retained prostheses and the materials employed or the technology to manufacture the prostheses.

CONCLUSION

The influence of prosthetic design on implant survival in OLP patients is still poorly understood, but important clinical recommendations can be drawn. The strength of evidence was grade 3b (CEBM) or low (GRADE).

Narrow-diameter implants versus regular-diameter implants for rehabilitation of the anterior region: a systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to evaluate studies comparing implant survival rates, marginal bone loss (MBL), and mechanical and biological complication rates between narrow-diameter implants (NDIs) and regular-diameter implants (RDIs) used for oral rehabilitation in the anterior region. The review was conducted according to the PRISMA checklist. Two independent reviewers performed a comprehensive search of the PubMed/MEDLINE, Embase, Scopus, and Cochrane Library databases for studies published until May 2020. A total of 843 implants (484 NDIs and 359 RDIs) were included. No significant difference in implant survival rate (risk difference (RD) 0.01, 95% confidence interval (CI) -0.01 to 0.03; P=0.34), MBL (standardised mean difference -0.51mm, 95% CI -1.29 to 0.26mm; P=0.19), mechanical complications (RD 0.01, 95% CI -0.02 to 0.04; P=0.40), or biological complications (RD 0.01, 95% CI -0.09 to 0.11; P=0.85) was found between the implant groups. Within the limitations of this study, it is concluded that NDIs are an effective alternative to RDIs due to similar survival rates, MBL, and mechanical and biological complication rates. However, future studies are highly encouraged due to the small number of interventional studies on this topic.

A Comparative Analysis of Implants Presenting Different Diameters: Extra-Narrow, Narrow and Conventional

This study aimed at performing a comparative analysis of the fracture resistance of implants, evaluating extra-narrow, narrow, and regular implants. Four groups containing 15 implants each were evaluated. Group 1 (G1): single-piece extra-narrow implants; Group 2 (G2): single-piece narrow implants; Group 3 (G3): Morse taper narrow implants with solid abutments; Group 4 (G4): Morse taper conventional implants with solid abutments. The implants were tested using a universal testing machine for their maximum force limit and their maximum bending moment. After obtaining the data, the Shapiro–Wilk, ANOVA, and Tukey (p < 0.05) statistical tests were applied. Samples from all the groups were analyzed by scanning electron microscopy and Groups 3 and 4 were analyzed by profilometry. The means and the standard deviation values for the maximum force limit (N) and the maximum bending moment (Nmm) were respectively: G1:134.29 N (10.27); G2:300.61 N (24.26); G3:360.64 N (23.34); G4:419.10 N (18.87); G1:1612.02 Nmm (100.6); G2:2945 Nmm (237.97); G3:3530.38 Nmm (228.75); G4:4096.7 Nmm (182.73). The groups behaved statistically different from each other, showing that the smallest diameter implants provided less fracture resistance, both in the tensile strength tests and in the maximum bending moment between all groups. Furthermore, single-piece implants, with 2.5 mm and 3.0 mm diameters, deformed in the implant body region area, rather than in the abutment region.

Three-dimensional finite element analysis of two angled narrow-diameter implant designs for an all-on-4 prosthesis

STATEMENT OF PROBLEM

Although the concept of angulated dental implants has been used for the rehabilitation of the completely edentulous maxilla, its use has yet to be validated with narrow-diameter implants. Proper estimation of narrow-diameter implant dimensions and angulations is essential for the correct use of these implants.

PURPOSE

The purpose of this 3D finite element analysis study was to compare the stress levels and distributions of 2 narrow-diameter angled implant arrangements supporting a maxillary fixed complete prosthesis.

MATERIAL AND METHODS

Two commercially available narrow-diameter implants (3.5×11.5 mm, Unitite Prime; 2.9×11.5 mm, Unitite Slim) were compared for their performances under axial and oblique loading (masticatory force: 100 N) in simulated situations of all-on-4 treatment (2 parallel anterior implants perpendicular to the bone crest and 2 posterior implants angled at 30 degrees). An edentulous maxilla model generated from computed tomography and a prosthesis parametric computer-aided design (CAD) model were combined with computational models of implants and prosthetic components to represent implant-supported maxillary fixed complete prostheses. A condition of complete osseointegration was assumed. Peri-implant bone was analyzed by the Mohr-Coulomb criterion. Implants, abutments, and screws were analyzed by the von Mises criterion, and frameworks by the Rankine criterion.

RESULTS

The 3.5-mm model showed higher axial load values for peri-implant bone, implants, and abutments than the 2.9-mm model. As for oblique load, values were higher for right-sided peri-implant bone, implants, abutments, and frameworks in the 3.5-mm model than in the 2.9-mm model. The 3.5-mm model had a 16% lower risk of peri-implant bone loss for the axial load and 4% for the oblique load.

CONCLUSIONS

The biomechanical behavior of an angled 2.9-mm implant was comparable with that of a 3.5-mm implant for an all-on-4 prosthesis. However, despite a lower risk of peri-implant bone loss, the 3.5-mm model had higher peak stress on implants and abutments than the 2.9-mm model.

Narrow implants (2.75 and 3.25 mm diameter) supporting a fixed splinted prostheses in posterior regions of mandible: one-year results from a prospective cohort study

BACKGROUND

Can multiple splinted narrow-diameter implants be used as definitive implants in patients with insufficient bone ridge thickness in posterior regions of the mandible? With this aim, we evaluated their outcomes in this set up to 1 year after loading.

METHODS

Forty-two patients with a mean age of 61.3 years old (range 49-73) in need of fixed prosthetic implant-supported rehabilitations in the posterior region of the mandible, presenting a thin alveolar crest, were selected. One hundred twenty-four narrow-diameter implants (2.75 and 3.25 mm diameter) were placed and splinted with a bridge. One implant for each missing tooth was requested to be inserted. Outcomes measured were implant survival, complications, and marginal bone level changes up to 1 year after loading.

RESULTS

At the 12-month follow-up, three implants failed. Two 2.75 mm diameter implants and one 3.2 mm diameter implant failed. The implant survival rate was 97.6%. Peri-implant bone resorption was 0.20 mm (CI 95% 0.14: 0.26) after 6 months and 0.47 mm (CI 95% 0.29; 0.65) after 12 months of loading, not different between 2.75 and 3.25 mm diameter groups (p = 0.786). Of the 42 cases, three had an episode of peri-implant mucositis (7.1%).

CONCLUSIONS

Within the limits of this study, preliminary short-term data (1 year post-loading) suggested that narrow-diameter implants (2.75 to 3.25 mm) can be successfully used as a minimally invasive alternative to horizontal bone augmentation in the posterior mandible. However, larger and longer follow-ups of 5 years or more are needed.

Long-Term Effect of Surface Roughness and Patients' Factors on Crestal Bone Loss at Dental Implants. A Systematic Review and Meta-Analysis

Publications from 2011 to 2015 were selected to evaluate effect of implant surface roughness on long-term bone loss as surrogate for peri-implantitis risk. 87 out of 2,566 papers reported the mean bone loss after at least 5 years of function. Estimation of the proportion of implants with bone loss above 1, 2, and 3 mm as well as analysis the effect of implant surface roughness, smoking, and history of periodontitis was performed. By means of the provided statistical information of bone loss (mean and standard deviation) the prevalence of implants with bone loss ranging from 1 to 3 mm was estimated. The bone loss was used as a surrogate parameter for "peri-implantitis" given the fact that "peri-implantitis" prevalence was not reported in most studies or when reported, the diagnostic criteria were unclear or of dubious quality. The outcome of this review suggests that peri-implant bone loss around minimally rough implant systems was statistically significant less in comparison to the moderately rough and rough implant systems. No statistically significant difference was observed between moderately rough and rough implant systems. The studies that compared implants with comparable design and different surface roughness, showed less average peri-implant bone loss around the less rough surfaces in the meta-analysis. However, due to the heterogeneity of the papers and the multifactorial cause for bone loss, the impact of surface roughness alone seems rather limited and of minimal clinical importance. Irrespective of surface topography or implant brand, the average weighted implant survival rate was 97.3% after 5 years or more of loading. If considering 3 mm bone loss after at least 5 years to represent the presence of "peri-implantitis," less than 5% of the implants were affected. The meta-analysis indicated that periodontal history and smoking habits yielded more bone loss.

Is Alveolar Ridge Split a Risk Factor for Implant Survival?

PURPOSE

There is a paucity of studies that have assessed the long-term outcomes of the alveolar ridge split (ARS). This study evaluated the intraoperative and postoperative complications and assessed the placed dental implant and prosthesis.

MATERIALS AND METHODS

A retrospective study of the ARS was conducted in a single private dental clinic. The predictor variable was the ARS technique (1 stage vs 2 stages). The primary outcome was the dental implant survival rate. Secondary outcomes were intraoperative complications, marginal bone loss, prosthetic complications, and prosthesis success rate. Descriptive analysis was performed for patients' demographic data, implant details, and prosthetic complications. The Kaplan-Meier method was used to assess implant survival rate and prosthesis success rate.

RESULTS

Twenty patients (mean age, 55 ± 6 yr) had a mean follow-up time of 5 years. Delayed implant placement was performed when the residual alveolar bone width was narrower than 3 mm. No intraoperative or postoperative complications were reported. The survival rate of the 31 implants was 100% and the prosthesis success rate was 96.8%.

CONCLUSIONS

The ARS is an effective technique for horizontal bone augmentation in the mandible. Delayed dental implant placement when the alveolar bone width is narrower than 3 mm could minimize the risk of buccal wall fracture.