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

Insertion Torque, Removal Torque, and Resonance Frequency Analysis Values of Ultrashort, Short, and Standard Dental Implants: An In Vitro Study on Polyurethane Foam Sheets

Short implants were introduced to reduce morbidity, treatment duration, and complex bone regeneration interventions in atrophic jaws and to improve patient-reported outcomes. This study aimed to determine the insertion torque (IT), removal torque (RT), and resonance frequency analysis (RFA) values of ultrashort (3 mm length), short (7 mm length), and standard implants (10 mm length) inserted in 1-, 2-, 3-, and 4-mm thickness polyurethane sheets with densities of 10, 20, and 30 pounds per cubic foot (PCF). Standard-length implants were the gold standard (control). Overall, short-length implant IT values were higher or similar to the control in most experimental conditions. Those inserted into a 3 mm/30 PCF lamina showed the highest IT values, whereas 5 mm diameter ultrashort-length implants inserted into 2 and 3 mm/20 PCF laminas were higher than other implants. RT values followed the same trend and RFA values were more appreciable in short- and standard-length implants in all the scenarios. However, ultrashort-length implants reached a primary stability comparable to that of standard implants in lower thicknesses. In conclusion, although further studies are needed to corroborate this in vitro model with preclinical and clinical studies, our data shed light on short- and ultrashort-length implants geometries to a potential application in critical atrophy of the posterior jaws.

Comparação da expansão óssea promovida pela técnica de osseodensificação com dois tipos de conjunto de fresas

Resumo Introdução A estabilidade primária é um importante indicador de sucesso da osseointegração. Porém, fatores locais com osso de baixa intensidade podem interferir negativamente na obtenção da estabilidade primária. Objetivo O presente estudo avaliou o efeito de diferentes direções, velocidades de rotação e sistemas de fresagem na expansão de perfurações e estabilidade de implantes instalados em blocos mimetizando osso do tipo IV. Material e método Foram instalados 50 implantes em blocos de poliuretano sólido rígido. Esses implantes foram igualmente divididos em cinco grupos (n = 10): 1) Fresa Maximus (utilizadas no sentido horário a 1200rpm); 2) Fresa Maximus (utilizadas no sentido horário a 600rpm); 3) Fresa Neodent (utilizadas no sentido horário a 800rpm); 4) Fresa Neodent (utilizadas no sentido anti-horário a 800rpm); 5) Fresa Neodent (utilizadas no sentido anti-horário a 600rpm). Foram executadas análises de estabilidade dos implantes através de testes de torque de inserção e remoção, além das análises de frequência de ressonância. Adicionalmente, a expansão associada às perfurações promovida pelas brocas foi avaliada por meio de análises tomográficas. Resultado Verificou-se que os implantes instalados após o preparo da perfuração com as brocas Maximus a 600rpm apresentaram valores de torque de inserção maiores, quando comparados ao grupo de implantes instalados em perfurações confeccionadas com brocas Neodent. Ademais, as brocas Maximus apresentaram valores de expansão maiores que as brocas Neodent. Conclusão As brocas Maximus são mais eficientes em promover a osseodensificação, e sua utilização está associada ao aumento da estabilidade dos implantes instalados em blocos mimetizando osso do tipo IV.

Comparison of 6-mm and 11-mm dental implants in the posterior region supporting fixed dental prostheses: 5-year results of an open multicenter randomized controlled trial

Objective

The aim of this multicenter, randomized controlled trial was to compare the clinical and radiographic outcomes of 6‐mm or 11‐mm implants, placed in the posterior maxilla and mandible, during a 5‐year follow‐up period.

Materials and methods

Ninety‐five patients with adequate bone height for 11‐mm implants, were randomly allocated to a 6‐mm group (test group with short implants) or an 11‐mm group (control group with standard‐length implants). Two or three implants of the same length were placed in each patient and after 6 weeks loaded with a splinted provisional restoration. This was followed by definitive splinted restoration 6 months after implant placement. Clinical and radiographic parameters, including the occurrence of complications were recorded.

Results

A total of 49 patients were enrolled to receive 6‐mm implants (n = 108) and 46 patients to receive 11‐mm implants (n = 101). Three implants (two of 6 mm and one of 11 mm in length) were lost before loading and one 6‐mm implant after 15 months of function, and one 11‐mm implant was lost during the first year of function. The 5‐year survival rates were 96.0% and 98.9% in the 6‐mm and 11‐mm group, respectively. The mean marginal bone level changes 5 years post‐loading were 0.01 ± 0.45 mm (bone gain) in the 6‐mm group and −0.12 ± 0.93 mm (bone loss) in the 11‐mm group (p = .7670). Clinical parameters, including plaque, bleeding on probing and pocket probing depth were not significantly different between the groups, and also technical complications were low.

Conclusion

The clinical and radiographic outcomes of 6‐mm short and 11‐mm standard‐length implants were not different during a 5‐year evaluation period.

Evaluation of Implants with Different Macrostructures in Type I Bone-Pre-Clinical Study in Rabbits

The objective of this study was to assess the primary stability and the osseointegration process in implants with different macrostructures (Cylindrical vs. Hybrid Conical) in rabbit tibiae. Twenty-four (24) rabbits were used, divided into 3 experimental periods (2, 4 and 8 weeks) with 8 animals each. Each animal bilaterally received 2 implants from each group in the tibial metaphysis: Cylindrical Implant (CI) and Hybrid Conical Implant (HCI). All implants were assessed for insertion torque. After the experimental periods, one of the implants in each group was submitted to the removal counter-torque test and descriptive histological analysis while the other implant was used for microtomographic and histometric analysis (%Bone-Implant Contact). HCI implants showed higher insertion torque (32.93 ± 10.61 Ncm vs. 27.99 ± 7.80 Ncm) and higher % of bone-implant contact in the 8-week period (79.08 ± 11.31% vs. 59.72 ± 11.29%) than CI implants. However, CI implants showed higher values of removal counter-torque than HCI implants in the 8-week period (91.05 ± 9.32 Ncm vs. 68.62 ± 13.70 Ncm). There were no differences between groups regarding microtomographic data. It can be concluded that HCI implants showed greater insertion torque and bone-implant contact in relation to CI implants in the period of 8 weeks when installed in cortical bone of rabbits.

An In Vitro Evaluation, on Polyurethane Foam Sheets, of the Insertion Torque (IT) Values, Pull-Out Torque Values, and Resonance Frequency Analysis (RFA) of NanoShort Dental Implants

Objectives: The aim of this study was to investigate, in polyurethane foam sheets, the primary implant stability of a NanoShort implant compared to a self-condenser implant and to a standard, conventional implant. Materials and Methods: Three implant designs were evaluated in the present in vitro investigation: The Test implant (NanoShort), the Control A implant (self-condenser), and the Control B implant (standard design). The study was conducted by comparing the insertion torque values, the pull-out strength values, and the resonance frequency analysis (RFA) values of the Test and Control A and B implants inserted in polyurethane foam models of different thicknesses and densities. The foam densities were 10, 20, and 30 pounds per cubic foot (pcf). Three thicknesses of polyurethane foams (1, 2, 3 mm) were evaluated for a total of 640 experimental sites. Results: The Pearson correlation showed a moderate/strong correlation between all study groups (r > 0.3) for insertion torque and pull-out strength levels. Increased stability of the Test implants was obtained in 3 mm polyurethane sheets. The 2.5 and 3.5 mm Test implants presented good stability in 3 mm polyurethane sheets of 20–30 pcf densities. The Control implants showed better results compared to the Test implants in 1, 2, and 3 mm polyurethane sheets with densities of 10, 20, and 30 pcf. Conclusions: The NanoShort dental implant evaluated in this in vitro study showed a high level of stability in some experimental conditions, and could represent a useful tool, especially in the posterior mandible, as an alternative to vertical augmentation procedures.

Semiautomatic device for in vitro/ experimental bone perforation in dental implant research

PURPOSE

The present study presents a semiautomatic device developed to perform in vitro experiments using surgical drills for assisting dental implant research. It was built to perform tests independent of human direct contact, and contains an adjustable toolholder for engaging different types of implant contra angle hand pieces, in which different drills can be adapted. The researcher is able to make a range of adjustments on the machine, such as controlling the drilling force and depth.

MATERIALS AND METHODS

The device was tested on samples of both synthetic and natural bone with type I density, and a sequence of drills selected to perform the perforations. Drilling time and perforation force exerted during drilling were evaluated, as both parameters are required to be standardized.

RESULTS

It was observed that the drilling performed using the device was uniform using both types of bone, although the drilling time for the synthetic bone was higher. All perforations were exactly on the spot previously determined, and without variations in drill angulations. The perforation force was higher for the lance pilot drill for both bone types, and the natural bone required a higher axial force than the synthetic bone.

CONCLUSION

Thus, we consider this device trustable to perform standardized analysis and provide accurate results. It can be used for tests performed in universities and companies that develop dental implant materials and products.

Influence of short implants geometry on primary stability

BACKGROUND

A correct design is needed in short implants to improve primary stability (PS) in low quality bone. This study aimed to compare PS of double thread and single thread short implants.

MATERIAL AND METHODS

Thirty implants with single thread design (PHI/SHORT-I) and 30 implants with double thread design (PHIA/SHORT-I) (Radhex®, Inmet-Garnick S.A., Guadalajara, Spain) were placed in 30 randomly selected bovine ribs. PS was assessed in implant stability quotients (ISQ) and periotest values (PV) with Osstell™ and Periotest® devices, respectively. Computed tomographies of the ribs were taken and bone quality was evaluated in Hounsfield Units (HU) using Ez3D Plus software (Vatech Co., Korea). Only implants placed in low quality bone according to Misch and Kircos classification were selected (D3 bone: 350-850 HU; and D4 bone: 150-350 HU). Ten implants were not included in the study for being placed in D1 and D2 bone. Finally, 50 implants were selected: 17 and 9 PHI/SHORT-I in D3 and D4 bone respectively, and 15 and 9 PHIA/SHORT-I in D3 and D4 bone respectively.

RESULTS

The one-way ANOVA showed statistically significant differences in ISQ (61.35 ± 4.77 in PHI/SHORT-I and 66.43 ± 4.49 in PHIA/SHORT-I, P<0.005) and PV (-2.76 ± 0.8 and -4.11 ± 1.24 respectively, P<0.005) between two implant designs in D3 bone, and statistically significant differences in ISQ (53.44 ± 3.34 in PHI/SHORT-I and 60.56 ± 1.53 in PHIA/SHORT-I, P<0.0001) and PV (1.13 ± 0.95 and -2.5 ± 0.61 respectively, P<0.0001) between two groups in D4 bone.

CONCLUSIONS

Double thread design short implants resulted to have higher PS in comparison with single thread design short implants in D3 and D4 bone.