A Four-Year Survival Rate Multicenter Prospective Clinical Study on 377 Implants: Correlations Between Implant Insertion Torque, Diameter, and Bone Quality

Do dental implants installed in different types of bone (I, II, III, IV) have different success rates? A systematic review and meta-analysis

Purpose

The objective of this systematic review and meta-analysis was to evaluate the survival rate of implants installed in bone type IV (Lekholm and Zarb, 1995) compared to that of implants installed in bone types I, II, and III.

Material and methods

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA) and was registered in the PROSPERO International Database of Systematic Reviews (CRD42021229775). The PubMed/MEDLINE, Scopus, and Cochrane databases were searched through July 2021. The PICO question was: "Dental implants installed in type IV bone have a lower success rate when compared to implants installed in type I bone, II and III?". The established inclusion criteria were: 1) controlled and randomized clinical trials (RCT), 2) prospective and retrospective studies with at least 10 participants with dental implants, and 3) patients with dental implants installed in bone tissue types I, II, III, and IV (Lekholm and Zarb, 1985). The minimum followup duration was 1 year.

Results

After searching the identified databases, 117 articles were selected for full reading and 68 were excluded. Thus, 49 studies were included for qualitative and quantitative analyses. The total number of participants included was 12,056, with a mean age of 41.56 years and 29,905 implants installed. Bone types I, II, and III exhibit a lower implant failure rate when compared to bone type IV.

Conclusion

Dental implants installed in bone types I, II, and III showed significantly higher survival rates than those installed in type IV. The bone type I success rate was not significantly different than that of type II; however, the success rate of bone type I and II was higher than that of type III.

Survival rates of ultra-short (<6 mm) compared with short locking-taper implants supporting single crowns in posterior areas: A 5-year retrospective study

Background

Short and ultra‐short implants represent a predictable treatment, in terms of implant survival, with patients presenting insufficient available bone volumes. Moreover, single crown restorations represent a gold standard in terms of oral hygiene.

Purpose

The aim of this retrospective study was to evaluate implant survival, marginal bone loss, and peri‐implant complications in 333 locking‐taper short and ultra‐short implants.

Materials and Methods

Implants were placed in the maxillary and mandibular posterior regions of 142 patients. Clinical and radiographic examinations were performed at 5‐year recall appointments.

Results

All implants placed consisted of 8.0‐, 6.0‐, and 5.0‐mm length, 38.14%, 34.53%, and 27.33%, respectively. Three hundred thirty‐two implants (one early failure) were rehabilitated with single crowns in 141 patients. In 45.48% of the implants the crown‐to‐implant ratio was ≥2, with a mean value of 1.94. Overall implant‐based survival after 5 years of follow‐up was 96.10%: 96.85%, 95.65%, and 95.60% for 8.0‐, 6.0‐, and 5.0‐mm length implants, respectively (p = 0.82). Overall patient‐based survival was 91.55%. Regarding crestal bone level variations, average crestal bone loss and apical shift of the “first bone‐to‐implant contact point” position were 0.69 and 0.01 mm, respectively. Setting the threshold for excessive bone loss at 1 mm, during the time interval from loading to follow‐up, 28 implants experienced loss of supporting bone greater than 1 mm: 19 of them (67.85%) were surgically treated with a codified surgical regenerative protocol. After 60 months, a peri‐implantitis prevalence of 5.94% was reported, with an overall implant success of 94.06%: 95.93%, 92.73%, and 93.10% for 8.0‐, 6.0‐, and 5.0‐mm length implants, respectively (p = 0.55).

Conclusion

Long‐term outcomes suggest that short and ultra‐short locking‐taper implants can be successfully restored with single crowns in the posterior area of the maxilla and mandible.

Innovative implant design for continuous implant stability: A mechanical and histological experimental study in the iliac crest of goats

OBJECTIVES

this in vivo study reports on mechanical torque data as well as the biological evaluation up to 6 weeks after placement of implants with a unique wide knife thread design in a goat iliac crest model. We hypothesized that implants with this thread design would show substantial primary stability at a continuous level toward secondary stability.

METHODS

64 MegaGen Anyridge® implants were used with diameters 3.5 mm, 4.0 mm, 5.0 mm and 6.0 mm (n = 8). Implants were placed monocortically in the iliac crest of 16 healthy female Saanen goats, both on the right (for torque measurements) and left side (for histology/-morphometry). Torque-in at implant installation and torque-out at 2 and 6 weeks of implantation was measured, as well as bone-to-implant contact (BIC) and bone-area between the screw threads (BA).

RESULTS

Histology showed intimate bone-to-implant contact with a maturating trabecular structure between 2 and 6 weeks. Torque values showed a dependency on implant diameter. For all implant diameters, torque-in values were similar to torque-out values at 2 weeks. At 6 weeks however, all torque-out values were significantly increased. BIC and BA percentages showed similar values for all diameters at both 2 and 6 weeks.

CONCLUSIONS

These results prove the absence of a lag-phase in implant stability for MegaGen Anyridge® implants in the goat iliac crest model. The increased torque-out values at 6 weeks without increasing BIC and BA percentages correlate with the observed maturation of bone-to-implant contact quality over time.

CLINICAL SIGNIFICANCE

It is a challenge to optimize implants with continuous primary stability and rapid transition into secondary stability to minimize the duration of the lag-phase. The results of this study prove the absence of a lag-phase in implant stability for MegaGen Anyridge® implants. Consequently, the data from this work are important for the treatment of individual patients 'translating' these findings into clinical implant procedures.

Can transfer type and implant angulation affect impression accuracy? A 3D in vitro evaluation

Impression accuracy is fundamental to achieve a passive fit between implants and the superstructure. Three transfer types were tested to evaluate the differences in impression accuracy and their efficiency in case of different implant angles. A master model with four implant analogues placed at 0°, 15° and 35° was used. 27 impressions were taken with three different types of impression coping: closed tray technique coping (CT), open tray technique coping (COT) and telescopic open tray coping (TOT). The impressions were poured. Analogues were matched with scan bodies to be scanned and exported in STL. An implant bar was designed from each STL and another one from the master model. A comparison between these bars was obtained. Linear and angular measurements for every type of coping were calculated for different angulations. The collected data were analyzed with ANOVA test (95% of confidence). Student’s t test showed a significative discrepancy (p ≤ 0.001) on linear and angular measurements on Δx, Δy, Δz with different transfer types as well as diverse implant positioning angles (p ≤ 0.001). Within the limitations of this study, it can be concluded that the coping type and the implants divergence may be significant parameters influencing the impression accuracy.

Assessment of Peri-Implant Soft Tissues Conditions around Short and Ultra-Short Implant-Supported Single Crowns: A 3-Year Retrospective Study on Periodontally Healthy Patients and Patients with a History of Periodontal Disease

The aim of this retrospective study was to evaluate implant survival, marginal bone loss and peri-implant complications in 326 short and ultra-short implants. Implants were placed in the maxillary and mandibular posterior regions of 140 patients with (PP) and without (NPP) a history of periodontal disease. Clinical and radiographic examinations were performed at 3-year recall appointments. The 8.0, 6.0 and 5.0 mm-length implants placed in PP and NPP were respectively 43.75% and 38.46%, 35.10% and 34.19%, 21.15% and 27.35%; 325 implants (one early failure) were rehabilitated with single crowns in 139 patients. Overall implant survival after 3 years of follow-up was 97.55%, 98.08% and 96.61% for PP and NPP (p = 0.46). Crestal bone level variations were not statistically different among PP and NPP; 15.41% of implants presented signs of mucositis, 14.71% and 16.67% in PP and NPP (p = 0.64). Setting the threshold for bone loss at 2 mm after 36 months, peri-implantitis prevalence was 2.2%, 1.96% and 2.63% in PP and NPP (p = 0.7). Overall implant success was 82.39%, 83.33% and 80.7% for PP and NPP (p = 0.55). Short-term outcomes suggest that short and ultra-short locking-taper implants can successfully be restored with single crowns in the posterior jaws both in PP and NPP.

Inverted body-shift concept in macroimplant design to enhance biologic and esthetic outcomes: A clinical report

A new implant design to increase labial plate dimension and tooth-implant distance in maxillary anterior extraction sockets over traditional tapered implant designs is presented. Generally, tapered implants are divergent and wider at the coronal aspect of the implant adjacent to the lowest bone volume. Decreasing bone around implants over time can lead to ridge collapse, recession, and a graying effect of the gingival tissues that eventually impacts esthetic outcomes adversely. This implant design incorporates a body-shift in both diameter, shape, and thread pattern and reduces the coronal portion to allow greater circumferential bone thickness to be created where it is needed most for long-term stability.

Survival of Short and Ultra-Short Locking-Taper Implants Supporting Single Crowns in the Posterior Mandible: A 3-Year Retrospective Study

The purpose of this retrospective study was to determine survival and peri-implant marginal bone loss of short and ultra-short implants placed in the posterior mandible. A total of 98 patients received 201 locking-taper implants between January 2014 and January 2015. Implants were placed with a 2-stage approach and restored with single crowns. Clinical and radiographic examinations were performed at 3-year recall appointments. At that time, the proportion of implant survival by length, and variations of crestal bone levels (mean crestal bone loss and mean apical shift of the "first bone-to-implant contact point" position) were assessed. Significance level was set at 0.05. The total number of implants examined 36 months after loading included: 71 implants, 8.0 mm in length; 82 implants, 6.0 mm in length; and 48 implants, 5.0 mm in length. Five implants failed. The overall proportion of survival was 97.51%, with 98.59% for the 8.0-mm implants, 97.56% for the 6.0-mm implants, and 95.83% for the 5.0-mm implants. No statistically significant differences were found among the groups regarding implant survival (P = .73), mean crestal bone loss (P = .31), or mean apical shift of the "first bone-to-implant contact point" position (P = .36). Single-crown short and ultra-short implants may offer predictable outcomes in the atrophic posterior mandibular regions, though further investigations with longer follow-up evaluations are necessary to validate our results.

Managing restorative space, color matching, and tooth replacement with a novel implant through interdisciplinary treatment: A case report of partial anodontia and malformed teeth in the esthetic zone

A case report of tooth agenesis and excessive intraarch space due to tooth size discrepancies and malformed teeth is presented. Interdisciplinary treatment including orthodontics, implant surgery, prosthodontics, and laboratory fabrication with dissimilar restoration and material types was used to accomplish an esthetic and functional outcome. Proper diagnosis of individual tooth width and proportion were key elements in treatment. CLINICAL SIGNIFICANCE: Knowledge and understanding of the relationships of the mandibular to maxillary anterior teeth and shade management of dissimilar restoration types will allow the interdisciplinary team to achieve the desired esthetic restorative result.

Implant primary stability depending on protocol and insertion mode - an ex vivo study

Background

Dental implant primary stability is thought to be a fundamental prerequisite for the long-term survival and success. The aim of this study was to analyze the influence of protocol and insertion mode on dental implant stability ex vivo. One hundred and twenty implants were inserted either manually or machine-driven into porcine mandibles by a standard or over-dimensioned protocol. Dental implant stability was measured via resonance frequency analysis (RFA), insertion torque (IT), and torque out (TO).

Results

Statistically significant higher IT and TO values were seen after standard protocol insertion (p < 0.05), whereas manual and machine-driven insertion mode showed equivalent values.

Conclusions

The over-dimensioned protocol exceeded the primary stability values recommended for immediate implant insertion; therefore, it could be recommended as well.

Implant Diameter, Length, and the Insertion Torque/Depth Integral: A Study Using Polyurethane Foam Blocks

The amount of energy necessary to place an implant in its seat, described as the integral of the torque-depth curve at insertion (I), has been validated as a reliable measure of primary stability. This study aimed to investigate whether (I) may detect the variations in primary stability caused by changes in the implant length or diameter better than the insertion torque (IT). Cylindric implants featuring a double-etched, sandblasted surface with different diameters or lengths were placed into monolithic polyurethane foam blocks with different densities that mimicked human bone. (I)-, (I)*-, IT-, IT*-diameter and -length plots ((I)* and IT* were the derived values corrected for undersizing) were drawn and the relation between (I), (I)*, IT, and IT* and the fixture diameter or length was investigated with correlation analysis. (I)* and IT* correlated better than (I) and IT with the fixture diameter; (I), (I)*, IT, and IT* correlated equally well with the fixture length. In all cases, the slopes of the lines best fitting the experimental data were greater for (I) or (I)* than IT or IT*, respectively. (I) or (I)* were better detectors than IT or IT* of the changes in primary stability that can be achieved by increasing the fixture diameter or length.

Single-Crown, Short and Ultra-Short Implants, in Association with Simultaneous Internal Sinus Lift in the Atrophic Posterior Maxilla: A Three-Year Retrospective Study

As the atrophic posterior maxilla often presents serious limitations for dental implant procedures, a minimally invasive technique was proposed. The study aimed to retrospectively evaluate the outcomes of short and ultra-short locking-taper implants, placed in combination with a modified osteotome sinus floor elevation procedure (internal sinus lift technique) in the posterior maxilla. A total of 31 patients received 51 locking-taper implants. Clinical and radiographic examinations were performed before treatment, at loading time, and after three years. Seven implants of 8.0 mm, 23 implants of 6.0 mm, and 21 implants 5.0 mm in length were rehabilitated with single-crown restorations. Implant survival at three-year follow-up was 96.08%. Pre-operative residual crestal bone height of 5.2 (1.41) (median (interquartile range)) mm increased to 7.59 (1.97) mm at the 36-month follow-up, with an average intra-sinus bone height gain of 3.17 ± 1.13 (mean ± standard deviation) mm. Mean peri-implant crestal bone loss was 0.29 (0.46) mm and mean first bone-to-implant contact point shifted apically to 0.12 (0.34) mm. It can be suggested with confidence that implants used in the study, placed in conjunction with an internal sinus floor elevation technique, can be restored with single crowns as a predictable treatment for the edentulous regions of the posterior maxilla.

Primary Stability Optimization by Using Fixtures with Different Thread Depth According To Bone Density: A Clinical Prospective Study on Early Loaded Implants

Background: Macro- and micro-geometry are among the factors influencing implant stability and potentially determining loading protocol. The purpose of this study was to test a protocol for early loading by controlling implant stability with the selection of fixtures with different thread depth according to the bone density of the implant site. Materials and Methods: Patients needing implant therapy for fixed prosthetic rehabilitation were treated by inserting fixtures with four different thread diameters, selected based on clinical assessment of bone quality at placement (D1, D2, D3, and D4, according to Misch classification). Final insertion torque (IT) and implant stability quotient (ISQ) were recorded at baseline and ISQ measurements repeated after one, two, three, and four weeks. At the three-week measurement (four weeks after implant replacement), implants with ISQ > 70 Ncm were functionally loaded with provisional restorations. Marginal bone level was radiographically measured 12 months after implant insertion. Results: Fourteen patients were treated with the insertion of forty implants: Among them, 39 implants showing ISQ > 70 after 3 weeks of healing were loaded with provisional restoration. Mean IT value was 82.3 ± 33.2 Ncm and varied between the four different types of bone (107.2 ± 35.6 Ncm, 74.7 ± 14.0 Ncm, 76.5 ± 31.1 Ncm, and 55.2 ± 22.6 Ncm in D1, D2, D3, and D4 bone, respectively). Results showed significant differences except between D2 and D3 bone types. Mean ISQ at baseline was 79.3 ± 4.3 and values in D1, D2, D3, and D4 bone were 81.9 ± 2.0, 81.1 ± 1.0, 78.3 ± 3.7, and 73.2 ± 4.9, respectively. Results showed significant differences except between D1 and D2 bone types. IT and ISQ showed a significant positive correlation when analyzing the entire sample (p = 0.0002) and D4 bone type (p = 0.0008). The correlation between IT and ISQ was not significant when considering D1, D2, and D3 types (p = 0.28; p = 0.31; p = 0.16, respectively). ISQ values showed a slight drop at three weeks for D1, D2, and D3 bone while remaining almost unchanged in D4 bone. At 12-month follow-up, all implants (39 early loading, 1 conventional loading) had satisfactory function, showing an average marginal bone loss of 0.12 ± 0.12 mm, when compared to baseline levels. Conclusion: Matching implant macro-geometry to bone density can lead to adequate implant stability both in hard and soft bone. High primary stability and limited implant stability loss during the first month of healing could allow the application of early loading protocols with predictable clinical outcomes.

Influência da topografia de superfície nanométrica na estabilidade primária de mini-implantes dentários

Resumo Introdução A modificação físico-química da superfície de mini-implantes utilizados no suporte de overdentures pode influenciar o desempenho mecânico dos mesmos. Objetivo Avaliar a influência de um tratamento de superfície do tipo nanométrico no desempenho mecânico de novos designs de mini-implantes. Material e método Foram utilizados 40 mini-implantes (Ti-6Al-4V), com Ø 2 mm × 10 mm de comprimento e dois designs diferentes, rosqueado e helicoidal, divididos em quatro grupos (n=10), de acordo com o modelo e a presença ou a ausência de tratamento superficial. O desempenho mecânico foi avaliado por meio de torque de inserção e ensaio de arrancamento em cilindros ósseos suínos. Análise de variância ANOVA e teste de Tukey, com significância de 5%, foram utilizados para análise estatística dos dados. Resultado Foi observada diferença estatisticamente significante entre os grupos com e sem tratamento para torque de inserção (p<0,001), e ensaio de arrancamento (p=0,006), sendo a maior média para o grupo com tratamento, independentemente do design. Na comparação entre os designs, o rosqueado apresentou média significativamente maior (p<0,001) que o helicoidal. Conclusão: O tratamento de superfície nanométrico viabilizou melhor desempenho mecânico dos mini-implantes avaliados. Com relação aos novos designs testados, o rosqueado apresentou resultados superiores ao helicoidal.

Insertion Torque of Variable-Thread Tapered Implants in the Posterior Maxilla: A Clinical Study

PURPOSE

Primary stability is a key factor for successful implant osseointegration, especially in poor bone quality and early/immediate loading. In the immediate loading protocol, insertion torque values (ITVs) have been suggested to be the most valid prognostic factor for osseointegration of maxillary implants. The objectives of this study were to: (1) evaluate ITVs achieved by a variable-thread tapered implant in the posterior maxilla; and (2) assess the impact of bone quality, implant dimensions, bicortical anchorage, and implant location on ITVs.

MATERIALS AND METHODS

Twenty-six adult, systemically healthy patients received 173 variable-thread tapered implants in maxillary premolar and molar healed edentulous sites with a minimum subsinus height of 8 mm. Implant sites were prepared using the bone-quality adjusted drilling sequence according to manufacturer's recommendations. Bone quality was recorded subjectively during drilling based on Misch criteria (D1-D4), and ITVs were measured with a manual torque wrench. Univariate and multivariate analyses were performed at the 0.05 significance level.

RESULTS

First and second molar sites accounted for 46.8% of all implants. D4 bone was encountered in 61.3% of the sites. Most of the implants were 4.3 mm in diameter (59.5%), and lengths of 11.5 and 13 mm were most commonly used (75.2%). Approximately half of the implants were associated with apical cortical anchorage (51.4%). The overall mean ITV was 44.5 ± 23.0 Ncm, with 65.5 ± 15.6 Ncm, 55.5 ± 19.6 Ncm, and 36.6 ± 21.7 Ncm for D2, D3, and D4 bone, respectively. Bone quality and implant location significantly affected ITVs, while implant dimensions and apical cortical anchorage did not.

CONCLUSIONS

ITVs of variable-thread implants were significantly influenced by variations in bone quality and implant position in the posterior maxilla. Despite the influence of bone quality on primary stability, the mean ITVs attained with variable-thread tapered implants in poor bone quality were within the recommended range for immediate loading.

Correlation between Insertion Torque and Implant Stability Quotient in Tapered Implants with Knife-Edge Thread Design

Aim

To evaluate the correlation between insertion torque (IT) and implant stability quotient (ISQ) in tapered implants with knife-edge threads.

Methods

Seventy-five identical implants (Anyridge, Megagen) were inserted by using a surgical drilling unit with torque control and an integrated resonance frequency analysis module (Implantmed, W&H). IT (N/cm) and ISQ were recorded and implants were divided into three groups (n = 25) according to the IT: low (<30), medium (30 < IT < 50), and high torque (>50). ISQ difference among groups was assessed by Kruskal-Wallis test, followed by Bonferroni-corrected Mann–Whitney U-test for pairwise comparisons. The strength of the association between IT and ISQ was assessed by Spearman Rho correlation coefficient (α = 0.05).

Results

At the pairwise comparisons, a significant difference of ISQ values was demonstrated only between low torque and high torque groups. The strength of the association between IT and ISQ value was significant for both the entire sample and the medium torque group, while it was not significant in low and high torque groups.

Conclusions

For the investigated implant, ISQ and IT showed a positive correlation up to values around 50 N/cm: higher torques subject the bone-implant system to unnecessary biological and mechanical stress without additional benefits in terms of implant stability. This trial is registered with NCT03222219.

Clinical and Radiologic Outcomes of Submerged and Nonsubmerged Bone-Level Implants with Internal Hexagonal Connections in Immediate Implantation: A 5-Year Retrospective Study

PURPOSE

To evaluate the 5-year clinical and radiologic outcome of immediate implantation using submerged and nonsubmerged techniques with bone-level implants and internal hexagonal connections and the effects of potential influencing factors.

MATERIALS AND METHODS

A total of 114 bone-level implants (XiVE S plus) with internal hexagonal connections inserted into 72 patients were included. Patients were followed up for 5 years. A t-test was used to statistically evaluate the marginal bone loss between the submerged and nonsubmerged groups. The cumulative survival rate (CSR) was calculated according to the life table method and illustrated with Kaplan-Meier survival curves. Comparisons of the CSR between healing protocols, guided bone regeneration, implants with different sites, lengths, and diameters were performed using log-rank tests.

RESULTS

The 5-year cumulative implant survival rates with submerged and nonsubmerged healing were 94% and 96%, respectively. No statistically significant differences in terms of marginal bone loss, healing protocol, application of guided bone regeneration, implant site, or length were observed.

CONCLUSIONS

High CSRs and good marginal bone levels were achieved 5 years after immediate implantation of bone-level implants with internal hexagonal connections using both the submerged and nonsubmerged techniques. Factors such as implant length, site, and application of guided bone regeneration did not have an impact on the long-term success of the implants.

Failure torque of ceramic neck titanium implant

STATEMENT OF PROBLEM

Dental implants are typically made of titanium. However, with the current systems on the market, the implant neck often shows through the gingival tissues as a black or dark gray line and/or as a grayish discoloration of the peri-implant soft tissue.

PURPOSE

The purpose of this in vitro study was to test a new implant design. The key component of this design is the ceramic shell that covers the polished collar of the tissue-level titanium implant and masks its dark color to mimic natural dentition. The main purpose was to determine the maximum torque for fracturing the ceramic shell and compare it with clinical implant insertion torque value.

MATERIAL AND METHODS

Type 4 commercially pure titanium endosseous implants of 3 different diameters (3.3, 4.1, and 4.8 mm) were used. Porcelain was applied in 0.5-mm thickness to the polished collar of each implant. An axial-torsional universal testing machine was used to twist the implants until failure. The data (n=10) were statistically analyzed by ANOVA and the Tukey honest significant difference test (α=.05). The maximum torque for each diameter group was also compared with the optimum clinical implant insertion torque value of 35 Ncm (control) using a 1-sample t test.

RESULTS

None of the tested groups had a fractured ceramic shell. Instead, the implant carriers fractured at the maximum torque levels. Therefore, the fracture of the implant carriers was selected as the maximum (failure) torque value. A statistical difference was found for the failure torque between the 3.3-mm diameter and the other 2 diameters (P<.001) although no statistical differences were found between the 4.1-mm and 4.8-mm diameters (P=.106). A statistically significant difference was found between the failure torque of any one of the tested groups and the clinical insertion torque (P<.001).

CONCLUSIONS

The ceramic shells did not fracture. Instead, the implant carriers fractured at certain torque levels. These levels were sufficiently higher than the clinical torque values.

In Vitro Evaluation of the Primary Stability of Short and Conventional Implants

The objective of this study was to evaluate the primary stability of short and conventional dental implants with different platform types at different site densities in vitro. One hundred twenty implants were placed in polyurethane blocks that simulate different bone densities (bone types I and IV). The implants were divided into 10 groups, with 12 implants each according to the type of prosthetic connections (external hexagon, EH; morse taper, MT) and size of the implants (conventional: 4 × 10 mm; short: 5 × 5, 5.5 × 5, 5 × 6, and 5.5 × 6 mm). Insertion torque and resonance frequency analyses were performed to evaluate the primary stability. The Kruskal-Wallis test complemented by Dunn's test and the Mann-Whitney test were used for statistical analysis. These tests were applied at the confidence level of 95% (P < .05). The implants installed in blocks with density type IV exhibited reduced insertion torque compared with implants placed in blocks with density type I. Short implants with EH exhibited increased insertion torque compared with short implants with MT in blocks with bone density type I. In general, implants installed in blocks with density type I exhibited greater primary stability. The short implants with EH with a 5.5-mm diameter and the short implants with MT with a 5-mm diameter exhibited reduced primary stability. No differences between short and conventional implants were noted. Short implants have primary stability and insertion torque at least equivalent to conventional implants irrespective of the platform type and density of the site.

Torque Loss After Miniscrew Placement: An In-Vitro Study Followed by a Clinical Trial

To evaluate torque loss a week after insertion, both in an in vivo and an in vitro experimental setup were designed. In the in vivo setup a total of 29 miniscrews were placed in 20 patients who underwent orthodontic treatment. Maximum insertion torque (MIT) was evaluated at insertion time (T1). A week later, insertion torque was measured again by applying a quarter turn (T2); no load was applied on the screw during the first week. In the in vitro setup a total of 20 miniscrews were placed in pig rib bone samples. MIT was evaluated at insertion time (T1). Bone samples were kept in saline solution and controlled environment for a week during which the solution was refreshed every day. Afterwards, torque was measured again by applying a quarter turn (T2). The comparison of MIT over time was done calculating the percentage difference of the torque values between pre- and post-treatment and using the parametric two independent samples t-test or the non-parametric Mann–Whitney test. After a week unloaded miniscrews showed a mean loss of rotational torque of 36.3% and 40.9% in in vitro and in in vivo conditions, respectively. No statistical differences were found between the two different setups. Torque loss was observed after the first week in both study models; in vitro experimental setup provided a reliable study model for studying torque variation during the first week after insertion.

Use of Implant-Derived Minimally Invasive Sinus Floor Elevation: A Multicenter Clinical Observational Study With 12- to 65-Month Follow-Up

The aim of this study is to evaluate the performance of implant-derived minimally invasive sinus floor elevation. A multicenter retrospective study was performed in 5 dental clinics. Patients requiring sinus augmentation for single implant placement were recorded and followed up. The dental implant used in this trial was a self-tapping endosseous dental implant that contains an internal channel to allow the introduction of liquids through the implant body into the maxillary sinus; those liquids include saline and a flowable bone grafting material. Overall, 37 implants were installed in 37 patients. The age range of the patients was 37-75 years (mean: 51.2 years). The average residual bone height prior to the procedure was 5.24 ± 1 mm. Of all cases, 25 implants replaced the maxillary first molar and 12 replaced the maxillary second premolar. All surgeries were uneventful with no apparent perforation of the sinus membrane. The mean follow-up time was 24.81 ± 13 months ranging from 12 to 65 months. All implants integrated and showed stable marginal bone level. No adverse events were recorded during the follow-up period. The presented method for transcrestal sinus floor elevation procedure can be accomplished using a specially designed dental implant. Further long-term studies are warranted to reaffirm the results of this study.

Mechanical and Histological Effects of Resorbable Blasting Media Surface Treatment on the Initial Stability of Orthodontic Mini-Implants

Introduction. This study aimed to evaluate the effects of resorbable blasting media (RBM) treatment on early stability of orthodontic mini-implants by mechanical, histomorphometric, and histological analyses. Methods. Ninety-six (64 for mechanical study and 32 for histological study and histomorphometric analysis) titanium orthodontic mini-implants (OMIs) with machined (machined group) or RBM-treated (CaP) surface (RBM group) were implanted in the tibiae of 24 rabbits. Maximum initial torque (MIT) was measured during insertion, and maximum removal torque (MRT) and removal angular momentum (RAM) were measured at 2 and 4 weeks after implantation. Bone-to-implant contact (BIC) and bone area (BA) were analyzed at 4 weeks after implantation. Results. RBM group exhibited significantly lower MIT and significantly higher MRT and RAM at 2 weeks than machined group. No significant difference in MRT, RAM, and BIC between the two groups was noted at 4 weeks, although BA was significantly higher in RBM group than in machined group. RBM group showed little bone resorption, whereas machined group showed new bone formation after bone resorption. Conclusions. RBM surface treatment can provide early stability of OMIs around 2 weeks after insertion, whereas stability of machined surface OMIs may decrease in early stages because of bone resorption, although it can subsequently recover by new bone apposition.

Two-stage closed sinus lift: a new surgical technique for maxillary sinus floor augmentation

Bone tissue atrophy may constitute a relative contraindication for implantation. The methods used in reconstruction of the alveolar ridge within the lateral section of the maxilla have been well known but not perfect. Presentation of the two-stage, closed sinus lift technique as well as efficacy evaluation of reconstruction of the alveolar ridge in the maxilla within its vertical dimension with the use of this technique. The total procedure was performed in 26 out of 28 patients qualified for the study. The height of the alveolar ridge at the site of the planned implantation was no <3 mm, the width of the ridge was no <5 mm. During the treatment stage 1 the sinus lift was performed for the first time. The created hollow was filled with allogeneic granulate. After 3–6 months stage 2 was performed consisting in another sinus lift with simultaneous implantation. The treatment was completed with prosthetic restoration after 6 months of osteointegration. In 24 out of 26 cases stage 1 was completed with the average ridge height of 7.2 mm. In stage 2, simultaneously with the second sinus lift, 26 implants were placed and no cases of sinusitis were found. In the follow-up period none of the implants were lost. The presented method is efficient and combines the benefits of the open technique—allowing treatment in cases of larger reduction of the vertical dimension and the closed technique—as it does not require opening of the maxillary sinus.