Influence of an Alternative Implant Design and Surgical Protocol on Primary Stability

Relationship between dental implant macro-design and osseointegration: a systematic review

PURPOSE

This systematic review aimed to determine whether differences in the macro-geometry of titanium implants promote changes in osseointegration.

MATERIAL AND METHOD

SCOPUS, PubMed/Medline, Web of Science, and EMBASE databases were searched in June 2021. In addition, it was performed a manual search of the reference lists of the included articles. Eligibility criteria were in vivo studies that addressed the effect of titanium implant macro-geometry on osseointegration, studies that evaluated periodontally healthy models, and papers indexed in Journal Citation Reports.

RESULTS

The database search resulted in 1037 articles. Of the 19 articles selected for full reading, 16 remained in this systematic review. These had a high heterogeneity making it hard to perform statistical analysis of the data, so a descriptive analysis was performed.

CONCLUSIONS

Based on the studies included in this systematic review, implant macro-geometry provides influences on osseointegration. In this sense, the various isolated characteristics (thread type, thread pitch, thread depth, face angle) should be studied so that the implant geometry can balance the compressive stress and tensile stress and produce a minimum shear force.

How does dental implant macrogeometry affect primary implant stability? A narrative review

PURPOSE

The macrogeometry of a dental implant plays a decisive role in its primary stability. A larger diameter, a conical shape, and a roughened surface increase the contact area of the implant with the surrounding bone and thus improve primary stability. This is considered the basis for successful implant osseointegration that different factors, such as implant design, can influence. This narrative review aims to critically review macro-geometric features affecting the primary stability of dental implants.

METHODS

For this review, a comprehensive literature search and review of relevant studies was conducted based on formulating a research question, searching the literature using keywords and electronic databases such as PubMed, Embase, and Cochrane Library to search for relevant studies. These studies were screened and selected, the study quality was assessed, data were extracted, the results were summarized, and conclusions were drawn.

RESULTS

The macrogeometry of a dental implant includes its surface characteristics, size, and shape, all of which play a critical role in its primary stability. At the time of placement, the initial stability of an implant is determined by its contact area with the surrounding bone. Larger diameter and a conical shape of an implant result in a larger contact area and better primary stability. But the linear relationship between implant length and primary stability ends at 12 mm.

CONCLUSIONS

Several factors must be considered when choosing the ideal implant geometry, including local factors such as the condition of the bone and soft tissues at the implant site and systemic and patient-specific factors such as osteoporosis, diabetes, or autoimmune diseases. These factors can affect the success of the implant procedure and the long-term stability of an implant. By considering these factors, the surgeon can ensure the greatest possible therapeutic success and minimize the risk of implant failure.

Evaluation of Removal Force in Prosthetic Components of Morse Taper Dental Implants

The longevity of prosthetic rehabilitation is determined by the stability of the implant and abutment interfaces. True morse taper connections on dental restorations have been effective, however activation force still empirical. This work compared the activation strength and internal contact of Morse taper system according to the removal force. Eighty sets, composed of implants and prosthetic abutments, were evaluated with different internal contact areas; 15.12mm2 (G3.3) and 21.25mm2 (G4.3). The specimens were activated at 0° and 30°, with loads of 10, 20, 40 and 60N. The specimens were submitted to tensile test and the data to ANOVA and Tukey's tests (α=0.05). Representative specimens were examined under SEM. Removal force of G3.3 (2.15±1.33MPa) did not differed to G4.3 (1.99±1.03MPa). The activation at 0º (2.95±0.98MPa) statistically differed to 30º (1.19±0.54MPa). The 60N load was statistically superior for G3.3 and there was no statistical difference between 20N to 60N in G4.3. The values of 10N at 30o and 20N at the long axis of the morse taper implant, independent of the frictional contact area showed the best settlement.

Biomechanical and histological evaluation of four different implant macrogeometries in the early osseointegration process: An in vivo animal study

This study aims to evaluate the effects of implant macrogeometry on the early period of the osseointegration process, comparing four different implant models through biomechanical and histological analysis after implantation in rabbit tibiae. Twenty New Zealand rabbits were used, evaluated at two different times (21 and 28 days) after installation of the implant. Eighty implants with different macrogeometries were used, forming four groups (n = 20 per group): cylindrical implants Ø4.1 mm and 8 mm in length (STRc group); cylindrical-conical implants Ø4.1 mm and 8 mm in length (STRt group); tapered implants Ø4.3 mm and 8 mm in length (NOBt group); and tapered implants with healing chambers Ø4.0 mm and 8 mm in length (MAEt group). Ten samples from each group were analyzed at each proposed time. The initial implant stability quotient (ISQ) was measured by resonance frequency analysis, both at the time of installation and at the time of sacrifice. In the histological sections, the percentage of bone-implant contact (BIC%), newly formed bone, osteoid matrix, and medullary spaces were measured in the pre-determined cortical and medullary bone portion for each sample. The three tapered implant groups (STRt, NOBt, and MAEt) showed higher values for the analyzed parameters in the early osseointegration period, in comparison with the cylindrical implant group (STRc). In all parameters, the three tapered groups showed no difference (p > 0.05); however, all three tapered groups presented significant differences, when compared to the cylindrical group (p < 0.05). No correlation was detected between the parameters analyzed. Within the limitations of the present study, in all parameters analyzed, the tapered implants demonstrated greater results when compared to the cylindrical implants.

Correlation between bone volume fraction in posterior implant area and initial implant stability

OBJECTIVE

Bone volume fraction (BV/TV) was used as a quantitative indicator of bone mineral density (BMD) in the posterior dental implant area, and the relationship between it and the initial stability of the implant was analyzed.

METHODS

53 patients with posterior dental implantation were selected. Remove the bone fragments from the planting area and put them in the formalin solution. Then, the implant was placed after the operator prepared the hole step by step. Peak Insertion torque value (ITV) and Implant stability quotient (ISQ) were recorded. The BV/TV of the bone fragments was measured by Image pro Plus6.0. The correlation between it and ITV and ISQ was analyzed.

RESULTS

BV/TV was correlated with ITV and ISQ in the posterior dental planting area (r=0.862, r=0.832, P < 0.05). The correlation of the parameters in the posterior part of maxilla was higher than that in the mandible. There were significant differences in BV/TV, ITV, and ISQ between the mandible and maxilla, and the implant area of the mandible was higher than that of the maxilla.

CONCLUSION

BV/TV can provide an objective index for BMD in the implant area, which has an important influence on the evaluation of the initial stability of the implant.

A novel anatomic titanium mesh cage for reducing the subsidence rate after anterior cervical corpectomy: a finite element study

Fusion with a titanium mesh cage (TMC) has become popular as a conventional method after cervical anterior corpectomy, but postoperative TMC subsidence has often been reported in the literature. We designed a novel anatomic cervical TMC to reduce the postoperative subsidence rate. According to the test process specified in the American Society of Testing Materials (ASTM) F2267 standard, three-dimensional finite element analysis was used to compare the anti-subsidence characteristics of a traditional TMC (TTMC) and novel TMC (NTMC). Through analysis, the relative propensity values of a device to subside (Kp) of the TTMC and NTMC were 665.5 N/mm and 1007.2 N/mm, respectively. A higher Kp measurement is generally expected to indicate that the device is more resistant to subsidence into a vertebral body. The results showed that the novel anatomic titanium mesh cage (NTMC) significantly improved the anti-subsidence performance after anterior cervical corpectomy and fusion (ACCF), which was approximately 51.3% higher than that of the traditional titanium mesh cage.

Effects of implant thread design on primary stability-a comparison between single- and double-threaded implants in an artificial bone model

Background

Primary implant stability is essential for osseointegration. To increase stability without changing the implant size, the thread length must be extended by reducing pitch, using a double-threaded implant, or reducing pitch/lead and lead angle to half that of a single-threaded implant.

Materials and methods

We tested the stabilities of these configurations using artificial bone. A 1.2-mm pitch, single-threaded implant (12S) was the control. We tested a 0.6-mm pitch/1.2-mm-lead double-threaded implant (06D) and a 0.6-mm pitch/lead single-threaded implant (06S). We compared stabilities by measuring insertion torque, removal torque, and the implant stability quotient (ISQ). Damage to bone tissue caused by the implants was evaluated using microscopy and morphometric analysis.

Results

We show that 06D and 06S significantly improved stability compared with the 12S reference. The stability of 06S was significantly greater compared with that of 06D, except for ISQ. The three implants were associated with bone tissue damage characterized by debris and voids surrounding the implant/bone interface. The 06D caused the most tissue damage, followed by 06S and then 12S.

Conclusion

These findings indicate that primary stability was significantly improved by changing the implant size, extending the thread length with reduced pitch/lead, and reducing the lead angle to half that of a single-threaded implant compared with a double-threaded implant.

Comparison of histomorphometry and microradiography of different implant designs to assess primary implant stability

OBJECTIVES

To contribute toward optimizing the long-term stability of dental implants. Our working hypothesis was that the degrees of immediate implant-bone contact, and hence of primary stability, would demonstrably differ between implant systems due to their different external geometries and thread designs (macro-design). This demonstration was provided in a bovine model (ex vivo) by employing and comparing histomorphometry and microradiography as evaluation methods.

MATERIALS AND METHODS

A total of 120 implants, representing six different implant thread designs, were inserted following the recommended surgical protocol in ribs of freshly slaughtered cattle. Twenty specimens of implants with surrounding bone were prepared per system and were divided into two equally sized groups of 60 specimens for analysis by either histomorphometry or micro-computed tomography. Data were analyzed by Mann-Whitney U test (P ≤ .05).

RESULTS

One of the implant systems, featuring a slight tapered external geometry and a progressive thread design, consistently revealed the most favorable bone-implant contacts in both histomorphometric and microradiographic evaluations. Overall, consistently higher values of bone-implant contact were obtained with the microradiographic than the histomorphometric approach, and this difference reached statistical significance in three of the six implant systems tested.

CONCLUSIONS

Progressive threads offering a bone-condensing effect can significantly help to maximize implant-bone contact percentages. Compared to histomorphometry, microradiography is likewise a suitable method to evaluate bone-implant contact, offering the additional benefits of being noninvasive and less time consuming.

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.