Clinical Effectiveness of 6.5-mm-Long Implants to Support Two-Implant Fixed Prostheses in Premolar-Molar Region: The Influence of Immediate Loading and the Length of Splinting Implant.

PURPOSE: The purpose of this retrospective clinical study was to assess the influence of immediate loading and lengths of splinted implants on the clinical effectiveness of 6.5-mm-long implants supporting two-implant fixed prostheses in the premolar-molar regions. MATERIALS AND METHODS: A clinical database was reviewed in a private dental center to select those patients who had 6.5-mm-long implants placed to support two-implant fixed partial prostheses in the premolar-molar regions of the maxilla and the mandible. All implants were immediately loaded. The study groups were defined according to the lengths of the implants. Two groups were identified: the short-short splinted group, when both implants had 6.5 mm lengths, and the short-long splinted group, when one implant was longer than 6.5 mm. A total of 48 dental implants were placed in 16 patients to support 24 two-implant fixed prostheses. The mean follow-up time was 14 ± 5 months. The short-short splinted group included 8 patients with 16 implants; the short-long splinted group included 16 patients with 32 implants. The main variable was implant survival, and secondary outcomes were marginal bone stability and prosthesis survival. RESULTS: The statistical analyses indicated an absence of significant differences between the two groups in terms of implant and prosthesis survival (100% for both groups and both variables); however, distal bone loss around the splinted implants was significantly higher in the short-long splinted group. Bone loss was 0.37 ± 0.55 mm in the short-short splinted group and 0.94 ± 0.66 mm in the short-long splinted group. CONCLUSIONS: Immediate loading of short (6.5-mm-long) implants in the premolar-molar regions did not jeopardize their survival. Two-implant supported prostheses had the same clinical effectiveness, whether extra-short implants were splinted to another extra-short implant or to a longer one.

Performance mastigatória e impacto da saúde oral na qualidade de vida em pacientes reabilitados com prótese fixa implantossuportada com carga imediata / Masticatory performance and impact of oral health on quality of life in patients rehabilitated with implant-supported fixed prosthesis with immediate loading

O impacto da saúde oral na qualidade de vida (OHRQoL) dos pacientes através da substituição de próteses totais convencionais (PTC) por próteses fixas implantossuportadas (PFIS) ainda não está totalmente claro, devido à grande heterogeneidade metodológica. O objetivo desse ensaio clínico controlado não randomizado foi comparar a OHRQoL e a performance mastigatória (PM) em pacientes reabilitados com PTC e com PFIS com carga imediata na mandíbula. A amostra foi composta por 40 indivíduos com idade média de 59,08 anos (± 7,04), predominantemente do sexo feminino (n=36), distribuídos em dois grupos: PTC e PFIS. Todos os pacientes foram reabilitados com PTC inicialmente, 23 permaneceram com suas PTC, e o restante (17 pacientes), após 3 meses de uso das PTC tiveram suas próteses convertidas em PFIS com barra distal com carga imediata, sendo 7 suportadas por 3 implantes e 10 suportada por 4 implantes. O OHRQoL foi mensurado através do questionário OHIP-Edent (versão brasileira) e a PM, através do método das tamises com o X50 calculado. Dados foram coletados antes (T0), e após 3 meses da instalação das PTC e da PFIS (T1). Para a análise dos dados, Teste t de Student para amostras pareadas foi aplicado para avaliar o mesmo grupo antes e após a intervenção clínica, sendo na comparação entre os grupos aplicado o Teste t para grupos independentes e o "d" de Cohen calculado para ambas comparações. Teste de correlação de Spearman foi empregado para avaliar a correlação entre as variáveis. Os resultados mostraram que ao comparar o grupo PTC em T0 e T1, não houve melhora na OHRQoL e nem redução do X50, indicando que a PM não melhorou. Já no grupo PFIS, houve melhora significativa na OHRQoL (p < 0,001) com tamanho do efeito "muito grande" (Cohen'd = 2,49) e melhora significativa na PM com tamanho do efeito "muito grande" (Cohen' d = 2,47). Considerando a comparação no tempo T1 de ambos os grupos, o grupo PFIS apresentou menor valor de OHRQoL e menor valor de X50, indicando maior impacto positivo na qualidade de vida e melhor PM, quando comparado ao grupo PTC (p < 0,001). Constatou-se correlação entre a PM e o OHIP-Edent de forma positiva apenas para o grupo PTC, no tempo T0, no domínio "desconforto psicológico", indicando que a medida que a PM piorava, o desconforto psicológico aumentava. Concluiu-se que a conversão da prótese total convencional em prótese fixa implantossuportada impacta positivamente na qualidade de vida e na performance mastigatória dos usuários com um tamanho de efeito "muito grande" (AU).

Oral health impact on the quality of life (OHRQoL) of patients through the replacement of conventional complete dentures (CCD) to implant suported dentures (ISD) is still not completely clear due to the great methodological heterogeneity. The objective of this nonrandomized controlled clinical trial was to compare OHRQoL and masticatory performance (PM) in rehabilitated patients with CCD and ISD under lower immediate loading. The sample consisted of 40 individuals, mean age of 59.08 years (± 7.04), predominantly female (n = 36), were divided into two groups: CCD and ISD. All patients were rehabilitated with CCD initially, 23 remained with their CCD, and 17 patients after 3 months of CCD use had their dentures converted into ISD under immediate loading, supported by 3 or 4 implants. The OHRQoL was measured by OHIPEdent questionnaire (Brazilian version) and the PM, using the sieve method with the calculated X50. Data were collected before (T0), and after 3 months of installation of CCD and ISD (T1). Student's t-test for paired samples was applied to evaluate the same group before and after the clinical intervention, in the comparison between the groups the t test was applied for independent groups and the "d" of Cohen calculated for both groups comparisons. Spearman's correlation test was used to evaluate the correlation between the variables. Comparing the CCD group at T0 and T1, there was no positive impact on the OHRQoL and no significant X50 reduction, which indicates that there was no improvement in the PM. For ISD, there was an improvement in the OHRQoL (p < 0.001) with a large size effect (Cohen'd = 2,49) and a significant improvement in the PM with a large size effect (Cohen'd= 2,47). Comparison in time T1 for both groups, ISD presented lower OHRQoL and lower value of X50, which indicates a higher positive impact on the quality of life and better PM when compared to CCD (p < 0.001). Correlation between PM and OHIP-Edent was found only positively for CCD at time T0, in the "psychological discomfort" domain, indicating that as the PM worsens, the psychological discomfort increases. It is concluded that the conversion of complete dentures into implanted suported denture has a positive impact on the quality of life and on masticatory performance (AU).

Prospective Multicenter Clinical Cohort Study of a Novel Macro Hybrid Implant in Maxillary Anterior Postextraction Sockets: 1-Year Results.

A prospective cohort clinical study was performed to evaluate the concept and design of a novel macro hybrid implant placed into maxillary anterior postextraction sockets. Thirty-three patients with an equal number of hybrid implants were used to replace nonrestorable single anterior teeth with immediate tooth replacement therapy (immediate implant placement and immediate provisional restoration). The macro features of this hybrid implant are unique in geometry, as it combines two different shapes-a cylindrical coronal and tapered apical portion-into a singular body design, each comprising roughly half of the implant length. The hybrid design of this platform-switched implant also has a subcrestal angle correction, or Co-Axis feature, that facilitates screw-retained restorations. Mean implant survival at 1 year relative to primary stability, labial bone plate thickness with socket grafting at two reference points (L1 and L2), tooth-to-implant interproximal bone crest thickness, and pink esthetic score (PES) were evaluated. A mean insertion torque value of 65 Ncm (range 45 to 100 Ncm) was reached with the use of the tapered apical half of the implant body. No implants failed during an average healing period of 1 year. A labial plate dimension between 1.8 and 2.1 mm was attained immediately posttreatment and remained stable over time. A tooth-to-implant interdental bone crest distance and dimension of 2.3 to 2.6 mm was reached; it was also sustained at the 1-year follow-up. The average PES was 12.5 (range 9.0 to 14.0), with nearly 90% of treated sites with an "almost perfect" score. This macro hybrid implant in concept and design may be useful in immediate tooth replacement therapy of maxillary anterior postextraction sockets to achieve successful implant survival and esthetic outcomes, specifically labial plate and papilla preservation without midfacial or interdental tissue loss and discoloration.

Early Healing of Immediate Implants Connected With Two Types of Healing Abutments: A Prospective Cohort Study.

PURPOSE: To compare hard- and soft-tissue changes around immediate implants connected with 2 types of healing abutments during the early phases of healing. MATERIALS AND METHODS: Twenty-eight immediate implants were placed into molar/premolar sockets through a modified osteotomy method. The gaps around implants were grafted with deproteinized bovine bone mineral. According to the size of the alveoli, the implants were connected with titanium healing abutments (traditional group) or customized healing abutments (CA group). Radiographic and intraoral examinations were performed before surgery, postoperatively, and at the 6-month recall. RESULTS: Buccal (P = 0.717) and lingual (P = 0.087) vertical bone loss was comparable between groups. More significant incomplete defect fill was found at the distal aspect of the CA group (P = 0.000). The buccal bone thickness alterations were similar between the 2 groups (P = 0.902 at the implant platform). The mid-facial soft-tissue level was well maintained in both groups. CONCLUSIONS: Within the limitations of this study, for immediate implants placed into posterior sockets, customized healing abutments can facilitate closure of large sockets. Despite more pronounced incomplete defect fill, healing abutments consisting of polyether ether ketone and resin did not render an increased risk for periimplant bone loss or soft-tissue recession during the early healing period.

Immediate loading of subcrestally placed dental implants in anterior and premolar sites.

PURPOSE: Immediate loading of dental implants has been evolving into an appropriate procedure for the treatment of partially edentulous jaws. The purpose of this study was to evaluate the clinical success and radiological outcome of immediately and delayed loaded dental implants in anterior and premolar sites. MATERIALS AND METHODS: In this retrospective study, data of 163 individuals requiring tooth removal with subsequent implant placement in anterior and premolar sites were analyzed. Implants were immediately loaded by provisional acrylic resin bridges or loaded with delay. Implants were followed up annually for up to 9 years including intraoral radiographs. RESULTS: A total of 285 implants in 163 patients were placed. 218 implants were immediately loaded and 67 implants with delay. Fifteen implants failed during the follow-up period resulting in survival rates of 94.5% for immediate loading and 95.5% for delayed loading. After an initial decrease of 0.3 mm in the first 12 months the marginal bone level remained stable. No statistically significant differences were found in marginal bone loss between immediately and delayed loaded implants (P = 0.518, 95% CI). CONCLUSION: Within the limits of this study, immediate loading of immediately subcrestally placed dental implants in anterior and premolar sites is a reliable treatment option for dental rehabilitation.

Immediate One-Time Low-Profile Abutment to Enhance Peri-implant Soft and Hard Tissue Stability in the Esthetic Zone.

Reductions in peri-implant bone height have been acknowledged as a normal consequence of implant therapy. Various restorative factors contribute to this phenomenon. One is repeated abutment retightening, which causes a mechanical disruption at the implant-abutment interface, leading to soft tissue recession. Several investigators proposed placement of the definitive abutment after implant placement as a solution to the problem. The definitive use of an intermediate abutment after implant placement seems to positively affect the soft tissue response. This article aims to present a prosthetic sequence for achieving peri-implant tissue stability in the esthetic zone.

Conventional drills vs piezoelectric surgery preparation for placement of four immediately loaded zygomatic oncology implants in edentulous maxillae: results from 1-year split-mouth randomised controlled trial.

PURPOSE: To compare the outcome of site preparation for zygomatic oncology implants using conventional preparation with rotary drills or piezoelectric surgery with dedicated inserts for placing two zygomatic implants per zygoma according to a split-mouth design. MATERIALS AND METHODS: Twenty edentulous patients with severely atrophic maxillas not having sufficient bone volume for placing dental implants and less than 4 mm of bone height subantrally had their hemi-maxillas randomised according to a split-mouth design into implant site preparation with conventional rotational drills or piezoelectric surgery. Two zygomatic oncology implants (unthreaded coronal portion) were placed in each hemi-maxilla. Implants that achieved an insertion torque superior to 40 Ncm were immediately loaded with screw-retained metal reinforced acrylic provisional prostheses. Outcome measures were: prosthesis and implant failures, any complications, time to place the implants, presence of post-operative haematoma, and patient's preference by independent assessors. All patients were followed up to 1 year after loading. RESULTS: In two patients drills had also to be used at the piezoelectric surgery side to enable implant sites to be prepared. One implant for the conventional drill group did not achieve an insertion torque superior to 40 Ncm since it fractured the zygoma. No patients dropped out and two distal oncology implants failed in the same patient (one per group), who was not prosthetically rehabilitated. Six complications occurred at drilled sites and three at piezoelectric surgery sites (two patients had bilateral complications), the difference being not statistically significant (P (McNemar's test) = 0.375; odds ratio = 4.00; 95% CI of odds ratio: 0.45 to 35.79). Implant placement with convention drills took on average 14.35 ±â€…1.76 min and with piezoelectric surgery 23.50 ±â€…2.26 min, implant placement time being significantly shorter with conventional drilling (difference = 9.15 ±â€…1.69 min; 95%CI: 8.36 to 9.94 min; P < 0.001). Post-operative haematomas were more frequent at drilled sites (P = 0.001), and 16 patients found both techniques equally acceptable, while four preferred piezoelectric surgery (P = 0.125). CONCLUSIONS: Both drilling techniques achieved similar clinical results, but conventional drilling required 9 min less and could be used in all instances, although it was more aggressive. These results may be system-dependent, therefore they cannot be generalised to other zygomatic systems with confidence. Conflict-of-interest statement: This study was partially supported by Southern Implants (Irene, South Africa), the manufacturer of the zygomatic implants and the conventional drills evaluated in this study. However, data property belonged to the authors and by no means did the manufacturer interfere with the conduct of the trial or the publication of its results. Drs Felice and Pistilli developed the piezoelectric surgery zygomatic insert used in the present study.

Immediate and delayed loading of two-piece reduced-diameter implants with locator-analog attachments in edentulous mandibles: One-year results from a randomized clinical trial examining clinical outcome and patient expectation.

BACKGROUND: Prosthetic management of thin alveolar ridges in the edentulous mandibles of elderly patients, especially the time of loading, the number of implants needed, and patient expectations and perception, is a challenge in implant dentistry. PURPOSE: Survival of conventionally and immediately loaded 2-piece reduced-diameter implants in the interforaminal region of the edentulous mandible supporting locator-analog attachments was evaluated. Prosthetic complications and peri-implant hygiene were also studied, and patient expectation and subjective evaluation of the treatment were documented. MATERIAL AND METHODS: Twenty-five patients with adapted complete dentures received 4 reduced-diameter implants. All anterior implants were immediately loaded. Three months later, patients were allocated by randomization to 1 of 2 treatment groups: 2 locator-analog attachments on the anterior implants (Group A); or 4 locator-analog attachments (Group B). After another 3 months patient allocation was changed (crossover design) for the next 3 months. Questionnaires with Likert scales and numeric rating scales were used to assess patients' expectations and subjective overdenture-related variables, respectively. RESULTS: One implant was lost in the immediate-loading group. Survival was 98% and 100% for immediate and delayed loading, respectively. During 12-month observation, 8 complications required aftercare. At the beginning of treatment, patients' expectations were highly positive. Subjective assessment of overdenture-related variables 3 months after immediate loading of 2 implants revealed a statistically significant improvement for most of the variables studied; this was maintained 1 year later. In the subjective assessments, there were no statistically significant differences between Groups A and B. CONCLUSION: Immediate loading of reduced-diameter implants supporting locator-analog attachments resulted in high implant survival, few prosthetic complications, good oral hygiene, and improvement of subjective denture perception in the short-term. It might be a promising treatment option, especially for elderly patients with a narrow mandibular ridge.

Mandibular regeneration after immediate load dental implant in a periodontitis patient: A clinical and ultrastructural case report.

RATIONALE: In this case study, we characterized from radiographic, morphological and elemental point of view the mandibular reconstruction that occur in patients affects by periodontitis after application of endosseous titanium implants. In particular, we verified that the bone load applied by titanium implant was able to induce the mandibular osteogenic reconstruction. PATIENT CONCERN: A 57-year-old female active smoker with no contraindications for dental implants and 3 unstable dental prostheses, underwent open surgery for the application of endosseous titanium implants (BANP IMPLANT S.R.L., Milan, MI, Italy) with Immediate load dental implant technique. At the time of presentation, patient was under treatment ß- beta-adrenergic agents. DIAGNOSES: Patient was affected by grade II periodontitis according to Armitage classification. INTERVENTATION: Patient underwent open surgery for the application of endosseous titanium implants (BANP IMPLANT S.R.L., Milan, MI, Italy) with Immediate load dental implant technique. Implant placement was performed under local anesthesia after premedication with diazepam (0.2 mg/kg), given orally 30 minutes before surgery. After crestal incision, a meticulous cleaning of the oral cavity was carried out. We removed necrotic tissues and all inflammatory residues. Then, the bone cavity was extended gradually, according to the intended implant diameter. Inserted titanium implants were placed 8-12 mm subcrestally. OUTCOMES: We demonstrated that the bone load applied by titanium implant was able to induce the mandibular osteogenic reconstruction in a periodontitis patient. LESSONS: This case study can lay the foundation to improve understanding of the relationship between the immediate load dental implant and the mandibular regeneration.

A Retrospective 2-Year Clinical Study of Immediate Prosthetic Rehabilitation of Edentulous Jaws with Four Implants and Prefabricated Bars.

PURPOSE: The purpose of this retrospective investigation was to evaluate the use of a prefabricated bar system for immediately loaded implants placed and restored according to the All-on-Four concept with up to 24-month follow-up. MATERIALS AND METHODS: A total of 51 patients (31 males and 20 females; mean age 63.4 years) presented with edentulous or partially edentulous jaws with severe atrophy of the posterior regions. All patients were treated with full-arch fixed prostheses (28 maxillary, 34 mandibular) each supported by four implants (two vertical, two distally tilted). The implants were immediately loaded with screw-retained full-arch restorations. Each prosthesis was supported by a prefabricated metal bar combined with high-density acrylic resin. Follow-up visits were scheduled at 6, 12, and 24 months after initial prosthetic loading. Intraoral radiographs were obtained immediately after surgery and at each follow-up visit by using a custom radiograph holder and parallel technique. Marginal bone levels were assessed using digital image analysis. Implant and prosthetic survival and success rates were evaluated. Patient satisfaction was further assessed using a 100-mm visual analog scale (VAS). Data were compared by means of the Mantel-Haenszel test. RESULTS: No drop-outs occurred. The overall implant survival rates were 100% and 98.38% for the vertical and tilted implants respectively. Two of the 62 definitive fixed prostheses were lost during the observation period due to implant failure. Since restoration replacement due to implant failure was not judged a prosthodontic failure according to the survival criteria provided in this study, the overall prosthetic survival rate was 100%. No statistically significant differences in marginal bone levels between vertical and tilted implants were detected at 24-month follow-up evaluation in either jaw. All participants were functionally and esthetically satisfied with their definitive restorations after 2 years functioning, as confirmed by the average VAS scores (masticatory function: 99.7; phonetic function: 99.5, esthetics: 99.2). CONCLUSIONS: The preliminary 24-month results indicate that immediate loading of vertical and tilted implants using the evaluated prefabricated bar system may be a viable solution for edentulous jaw rehabilitation; however, more long-term prospective clinical trials are needed to affirm the effectiveness of this surgical-prosthetic protocol.

Different configuration of socket shield technique in peri-implant bone preservation: An experimental study in dog mandible.

The aim of this study was to evaluate the influence of the residual root and peri implant bone dimensions on the clinical success of the socket shield technique. Thirty-six dental implants were installed in 6 dogs. The clinical crowns of teeth P3, P4 and M1 were beheaded. Afterwards, the roots were worn down 2-3mm in apical direction until they were located at crestal level. Posterior implant beds were prepared in the center of the roots passing by 3mm apically forming 6 groups in accordance to the remaining root thickness. Radiography of the crestal bone level was performed on day 0 and after 12 weeks. Histomorphometric analyses of the specimens were carried out to measure the crestal bone level, the bone to implant contact and the buccal and lingual bone thickness at the implant shoulder portion. Correlations between groups were analyzed through nonparametric Friedman test, statistical significance was set as p<0.05. All 36 implants were osseointegrated, but 3 samples showed a clinical inflammatory reaction and some radicular fragments presented a small resorption process. On the buccal and lingual side, the radicular fragment was attached to the buccal bone plate by a physiologic periodontal ligament. In the areas where there was space between the implant and the fragment, newly formed bone was demonstrated directly on the implant surface. Within the limitations of an animal pilot study, root-T belt technique may be beneficial in preserving and protecting the bundle bone and preservation of soft tissues. If the thickness of the buccal bone is 3mm, and the thickness of the remaining root fragment is 2mm, the socket shield technique is more predictable and the bone contours can be maintained.

Accuracy of computer-guided surgery / La precisión de la cirugía guiada por ordenador

Dental implant fixation techniques are widely studied in order to reduce surgical morbidity. Computer-guided flapless surgery has been considered an efficient alternative that presents several advantages and some limitations. This technique allows the virtual planning and simulation of the prosthetic-surgical treatment that can help predict the difficulties and limitations in order to reduce possible errors. In addition to the prosthetic predictability, computer-guided surgery enhances accuracy and reduces surgical morbidity. Thus, the aim of this study was to report on a 7-year follow-up of immediately loaded implants inserted into an edentulous maxilla using virtual planning and flapless surgery.

Las técnicas de fijación del implante dental se estudian ampliamente para reducir la morbilidad quirúrgica. La cirugía sin flapless guiada por ordenador ha sido considerada como una alternativa eficiente con varias ventajas y algunas limitaciones. Esta técnica permite la planificación virtual y simulación del tratamiento protésico quirúrgico con la predicción de las dificultades y limitaciones para reducir posibles errores. Además de la previsibilidad de prótesis, la cirugía guiada por ordenador mejora la precisión y reduce la morbilidad quirúrgica. Por lo tanto, el objetivo de este estudio fue reportar a 5 años de seguimiento de los implantes de carga inmediata insertados en un maxilar desdentado utilizando la planificación virtual y la cirugía sin colgajo. El presente caso prospectivo informó el éxito del tratamiento y destacó la importancia de la planificación, lo que justifica el costo de esta tecnología.

A selective laser sintering prototype guide used to fabricate immediate interim fixed complete arch prostheses in flapless dental implant surgery: Technique description and clinical results.

STATEMENT OF PROBLEM: Extensive occlusal adjustments and misfit of the prosthesis to prosthetic components are frequent problems related to fixed interim prosthesis fabrication with immediate dental implant loading. PURPOSE: The purpose of this clinical trial was to evaluate a prosthetic guide made with a rapid prototype model based on virtual surgical planning. This prosthetic guide was used to fabricate fixed interim prostheses that would allow immediate implant loading after computer-guided implant installation. MATERIAL AND METHODS: Nine interim prostheses were made for 9 participants with complete maxillary or mandibular edentulism. The virtual prosthetic guide was planned using computer-assisted design (CAD) software and was fabricated with rapid prototyping equipment (selective laser sintering). The prosthetic guide had 3 portions: the occlusal portion, which had occlusal registration; the connection portion, which had the information of the position and angulation of the abutment/implant projection; and the mucosa portion, which had the registration of the alveolar mucosa architecture. The prosthetic guide was used by a dental technician to fabricate prostheses. A single trained examiner evaluated the passive fit of the interim prostheses, the average time required for installing the interim prosthesis and for occlusal adjustments, the satisfaction of the patient with the prosthesis; and the screws, torque, occlusion, and prosthesis status. RESULTS: Passive fit was achieved between the prosthetic components and prostheses in 7 participants. The average time required for installing the fixed interim prostheses was 64.44 minutes. All participants reported being more pleased with the fixed interim prosthesis than with the prosthesis worn before implant placement. Prosthesis fractures were observed in 3 participants (2 in the maxilla and 1 in the mandible); all fractures occurred 3 months or more after delivery. No further complication was observed during 6 months of follow-up. CONCLUSIONS: The prosthetic guide enabled fabrication of interim immediate prostheses that were easily seated and adjusted to accommodate any shifts in implant position occurring during computer-guided surgery. Immediate implant loading could be achieved in a reasonable operative time.

Effect of two different soft liners and thicknesses mediating stress transfer for immediately loaded 2-implant supported mandibular overdentures: A finite element analysis study.

STATEMENT OF PROBLEM: The use of soft liners as female receptacles for ball attachments retaining immediately loaded implant overdenture has been recommended to enhance osseointegration and provide a shock absorbing effect. However, which liner and which thickness is still unclear. PURPOSE: The purpose of this finite element analysis (FEA) study was to evaluate the effect of a 2- and 4-mm thickness of thermoplastic resin (TRL) and silicone-based liners (SBL) on the displacement and stresses transmitted to immediately loaded implants retaining a mandibular overdenture. MATERIAL AND METHODS: Four 3-dimensional (3D) FEA models of a mandibular implant overdenture retained by 2 ball attachments (2 models for each lining material with 2- or 4-mm liner thicknesses) were developed. Implants were placed in the canine regions and surrounded by a 1-mm cylinder of immature bone simulating immediate loading. A vertical and an oblique load of 150 N were applied in the right premolar molar regions. Stresses and displacement were set as output variables. RESULTS: Replacing the TRL by the SBL was associated with a decrease in stresses by 73% and in displacement by at least 46%. Increasing the thickness of any liner decreases stresses by 45% during vertical loading and by 25% during oblique loading and decreases displacement by 61.5% during vertical loading and by an average of 32.5% during oblique loading. None of the liners exceeded the experimental risk limits for micromotion at the bone-implant interface (50 µm). CONCLUSION: In immediately loaded mandibular implant overdentures, both SBL and TRL decrease the micromotion of implants and the stresses at the bone-implant interface. However, SBL is more effective. The thickness of both liners seems to play a major role in decreasing the stresses and displacement of periimplant tissues.

Effect of Osteotomy Preparation on Osseointegration of Immediately Loaded, Tapered Dental Implants.

The aim of the present preclinical in vivo study was to evaluate whether a modified "drill-only" protocol, involving slight underpreparation of the implant site, may have an effect on aspects of osseointegration of a novel bone-level tapered implant, compared with the "standard drilling" protocol involving taping and profiling of the marginal aspect of the implant socket. In each side of the edentulated and completely healed mandible of 11 minipigs, 2 tapered implants (8 mm long × 4.1 mm Ø, BLT; Institut Straumann AG, Basel, Switzerland) were installed either with the drill-only or the standard drilling protocol. Significantly lower average insertion torque values were recorded for the standard drilling protocol group (52 ± 29 Ncm) compared with the drill-only group (70 ± 27 Ncm) (t test, P ≤ 0.05); no significant difference was observed between the 2 groups regarding implant stability, by means of resonance frequency analysis (75 ± 8 vs. 75 ± 6, respectively). Half of the implants were immediately loaded and the rest were submerged, providing observation times of 8 or 4 wk, respectively. Non-decalcified histological and histomorphometric analysis of the implants with surrounding tissues showed no significant differences between the 2 drilling protocols regarding the distance from the implant platform to the first coronal bone-to-implant contact (f-BIC), the total bone-to-implant contact (BIC) as a percentage of the total implant perimeter, and the bone density in an area extending 1 mm laterally from the implant (BATA) within 2 rectangular regions of interest (ROIs) 4 mm in height, representing the coronal (parallel-walled) and apical (tapered) aspect of the implant (ROI 1 and ROI 2, respectively) in non-submerged implants. In general, marginal peri-implant bone levels were at or slightly apical to the implant platform, and large amounts of bone-to-implant contact were observed. In contrast, immediately loaded implants placed with the drill-only protocol showed statistically significantly lower BIC values (66% ± 13.7%) compared with those installed with the standard drilling protocol (74.8% ± 11.2%) (P = 0.018). In addition, although marginal bone levels were in most of the immediately loaded implants at or slightly apical to the implant platform, some of the implants installed with the drill-only protocol showed marginal bone loss and crater formation. Thus, in this model system, even slight underpreparation of the implant socket appeared to compromise osseointegration of immediately loaded bone-level tapered implants.

Implant-Supported Immediately Loaded Full-Arch Rehabilitations: Comparison of Resin and Zirconia Clinical Outcomes in a 5-Year Retrospective Follow-Up Study.

PURPOSE: We analyzed complications and failures of final full-arch implant-supported rehabilitations, comparing resin and zirconia prosthesis materials. Prostheses were retrospectively followed up for 5 years. MATERIALS AND METHODS: One hundred twenty-five patients who received one or two four to six implant-supported immediately loaded full-arch rehabilitations in resin (166 prostheses) or zirconia (48 prostheses) were analyzed. RESULTS: One hundred thirteen patients (53 men, 60 women), with 214 full-arch prostheses (105 maxillary, 109 mandibular), were analyzed. During the follow-up interval, the prosthesis annual complication rate was 6.6%, free complications survival was 75.5% (60 months). Age, number of implants, and prosthesis material did not influence complication risk. Men had a higher risk of complications than women. Prosthesis annual failure rate was 4.6%, free survival was 85.5% (60 months). Age, number of implants, and prosthesis material did not influence failure risk. Men and maxillary arch prostheses had a higher risk of failures than women and mandibular arch prostheses. CONCLUSION: Implant-supported, immediately loaded full-arch rehabilitations supporting resin or zirconia based prostheses were clinically successful in a 5-year follow-up. Prosthesis material did not influence complication risk.

Stability of smooth and rough mini-implants: clinical and biomechanical evaluation - an in vivostudy.

OBJECTIVE: To compare in vivo orthodontic mini-implants (MI) of smooth (machined) and rough (acid etched) surfaces, assessing primary and secondary stability. METHODS: Thirty-six (36) MI were inserted in the mandibles of six (6) dogs. Each animal received six (6) MI. In the right hemiarch, three (3) MI without surface treatment (smooth) were inserted, whereas in the left hemiarch, another three (3) MI with acid etched surfaces (rough) were inserted. The two distal MI in each hemiarch received an immediate load of 1.0 N for 16 weeks, whereas the MI in the mesial extremity was not subject to loading. Stability was measured by insertion and removal torque, initial and final mobility and by inter mini-implant distance. RESULTS: There was no statistical behavioral difference between smooth and rough MI. High insertion torque and reduced initial mobility were observed in all groups, as well as a reduction in removal torques in comparison with insertion torque. Rough MI presented higher removal torque and lower final mobility in comparison to smooth MI. MI did not remain static, with displacement of rough MI being smaller in comparison with smooth MI, but with no statistical difference. CONCLUSIONS: MI primary stability was greater than stability measured at removal. There was no difference in stability between smooth and rough MI when assessing mobility, displacement and insertion as well as removal torques.

Stability of smooth and rough mini-implants: clinical and biomechanical evaluation - an in vivostudy

Objective: To compare in vivo orthodontic mini-implants (MI) of smooth (machined) and rough (acid etched) surfaces, assessing primary and secondary stability.Methods:Thirty-six (36) MI were inserted in the mandibles of six (6) dogs. Each animal received six (6) MI. In the right hemiarch, three (3) MI without surface treatment (smooth) were inserted, whereas in the left hemiarch, another three (3) MI with acid etched surfaces (rough) were inserted. The two distal MI in each hemiarch received an immediate load of 1.0 N for 16 weeks, whereas the MI in the mesial extremity was not subject to loading. Stability was measured by insertion and removal torque, initial and final mobility and by inter mini-implant distance.Results:There was no statistical behavioral difference between smooth and rough MI. High insertion torque and reduced initial mobility were observed in all groups, as well as a reduction in removal torques in comparison with insertion torque. Rough MI presented higher removal torque and lower final mobility in comparison to smooth MI. MI did not remain static, with displacement of rough MI being smaller in comparison with smooth MI, but with no statistical difference.Conclusions:MI primary stability was greater than stability measured at removal. There was no difference in stability between smooth and rough MI when assessing mobility, displacement and insertion as well as removal torques.

Objetivo: comparar, in vivo, mini-implantes (MI) com superfície lisa (usinada) e porosa (tratada com ácido), avaliando sua estabilidade primária e secundária.Métodos:trinta e seis MI foram inseridos na mandíbula de seis cães, e cada animal recebeu seis MI. Na hemiarcada direita, foram inseridos três MI sem tratamento da superfície (liso); na esquerda, outros três com a superfície tratada com ácido (poroso). Os dois MI distais de cada hemiarcada receberam carga imediata de 1,0N durante dezesseis semanas, e o MI da extremidade mesial não recebeu carregamento. A estabilidade foi medida pelos torques de inserção e de remoção, pela mobilidade inicial e final, e pela distância inter-MI.Resultados:não houve diferença estatística do comportamento entre os MI lisos e porosos. No entanto, observou-se torque de inserção elevado e mobilidade inicial reduzida em todos os grupos. Para todos os grupos, houve redução dos torques de remoção, em relação ao de inserção. Os MI porosos apresentaram maior torque de remoção e menor mobilidade final, em relação aos MI lisos. Os MI não permaneceram estáticos, sendo o deslocamento dos MI porosos menor em relação aos MI lisos, mas sem diferença estatística.Conclusões:a estabilidade primária dos MI foi maior do que a estabilidade medida na sua remoção; não houve diferença na estabilidade entre os MI lisos e porosos ao avaliar-se a mobilidade, o deslocamento e os torques de inserção e remoção.