Formação óssea e contato osso-implante após irradiação e colocação do implante dentário: estudo experimental no modelo de tíbia em ratos / Bone formation and bone-implant contact after irradiation and dental implant placement: an experimental study in the rat tibiae model

Objetivo: comparar a formação óssea e o contato entre osso e implante (BIC) em osso irradiado usando um modelo de tíbia em ratos. Material e métodos: seis animais Rattus norvegicus (Wistar, 90 a 120 dias, peso entre 350 a 400 g) receberam 30 Gy de radiação ionizante (distância pele-fonte: 80 cm) na tíbia direita (grupo-experimental). A tíbia esquerda serviu como grupo-controle. Após 30 dias, implantes de titânio (2,5 mm diâmetro, 3 mm-comprimento, superfície tratada) foram colocados em ambos os grupos. Todos os animais foram sacrificados após 56 dias, e as amostras foram analisadas histomorfometricamente para área de formação óssea no espaço entre as roscas e o BIC. Resultados: para a formação óssea, as médias foram 44,91 ± 13,31% (grupo-controle), contra 43,16 ± 28,73% (grupo-experimental) (teste t; p=0,44). Para o contato entre osso e implante, o percentual foi de 39,51 ± 17,22% contra 33,36 ± 26,15%, respectivamente (teste t, p=0,31). Conclusão: dentro dos limites deste estudo, não houve diferença na formação óssea e no contato entre osso e implantes na avaliação histomorfométrica de implantes instalados em tíbias de ratos, submetidas previamente a 30 Gy de radiação ionizante.

Sleeping implant in the temporal bone: report of a case with 20-year follow-up.

BACKGROUND: There is limited knowledge of the long-term fate of "sleeping" or nonloaded implants in the temporal bone. PURPOSE: This article describes the fate of a fixture installed in the temporal bone that remained unloaded for 20 years. PATIENT AND METHODS: A 25-year-old male with hemifacial microsomia had three osseointegrated implants installed for an auricular episthesis and bone-anchored hearing aid (BAHA) in the left temporal bone in 1988. Two of the implants for the ear episthesis were activated the same year, but the fixture for the hearing aid was not uncovered until 2008. When the patient experienced hearing problems at his office, he wanted to reactivate the sleeping implant. An audiogram showed a maximum conductive hearing loss with good preserved cochlear function. Before reactivation, an Accuitomo three-dimensional, cone beam computed tomography was performed. Resonance frequency analysis (RFA) using the Ostell technique was done when the implant was uncovered. RESULTS: Preoperative x-ray investigation showed the sleeping implant to be well integrated in the temporal bone, covered with 1 mm bone, and with no signs of resorption. Geometric measurements correlating to the two loaded implants showed the sleeping implant to be positioned too close to these to be able to anchor a BAHA without interference with the episthesis. Surgical exploration was done to analyze the implant. The clinical status correlated well to that diagnosed from the x-ray investigation. RFA revealed the implant to be well integrated. A new fixture and abutment for BAHA was installed in the temporal line and activated 2 months after surgery. The patient is today supplied with a BAHA. CONCLUSION: It seems possible to use sleeping implants in the temporal bone even 20 years after installation.

Imaging of osseointegrated implants in the temporal bone by accuitomo 3-dimensional cone beam computed tomography.

OBJECTIVE: Follow-ups of osseointegrated implants in the temporal bone have been limited to clinical stability and resonance frequency measurements. Standard computed tomographic scanning is restricted because of the high radiation doses to the brain and the presence of disturbing metal artifacts. The present study was undertaken to evaluate the use of cone beam computed tomography preoperatively and postoperatively. STUDY DESIGN: Prospective investigation of patients intended for implant surgery and patients participating in a follow-up protocol. SETTING: Tertiary referral center. PATIENTS AND METHODS: Patients with osseointegrated implants and patients intended for implants in the temporal bone for bone-anchored epistheses and bone conduction hearing devices were investigated by a 3-D Accuitomo cone beam computed tomography machine. Images in sagittal, coronal, and axial planes were obtained and analyzed in a personal computer. Preoperative and postoperative views were analyzed regarding implant integration, bone resorption, anatomic landmarks, and implant failure. RESULTS: Eighteen patients were included in the study. With the used technique, it was easy to detect air cells, the sigmoid sinus, and posterior fossa and to recommend an ideal implant installation site. Bone resorption, bone overgrowth, and implant connex to air cells and dura were easy to detect. CONCLUSION: Accuitomo cone beam tomography showed to be a reliable method for investigating osseointegrated implants in the temporal bone.

Implications for contralateral bone-conducted transmission as measured by cochlear vibrations.

HYPOTHESIS: The velocity response at the contralateral cochlea from bone-conducted (BC) stimulation depends on the stimulation position. BACKGROUND: BC sound transmission in the human skull is complex and differs from air-conducted sound. BC sound stimulates both cochleae with different amplitudes and time delays influencing hearing perception in a way that is not completely understood. One important parameter is the stimulation position on the human skull. METHOD: By applying BC stimulation at 8 positions on both sides of 7 human cadaver skulls, the contralateral velocity response of the cochlear promontory was investigated in the frequency range of 0.1 to 10 kHz. Using previous data from ipsilateral stimulation, the transcranial transmission (TT) and effects of bilateral stimulation to one cochlea was calculated. RESULTS: The contralateral transmission from the 8 positions showed small differences, but the TT showed a generally increased cochlear separation when the stimulation position approached the cochlea. The effect of simultaneous bilateral stimulation was calculated, showing a low-frequency negative effect for correlated signals, whereas uncorrelated signals gave 3-dB gain. At higher frequencies, there was less interaction of the combined stimulation because of the greater intercochlear separation. Also, the greatest time difference between ipsilateral transmission and contralateral transmission was at positions close to the cochlea. CONCLUSION: The stimulation position only slightly affects the amplitude and phase of the contralateral cochlear velocity response. However, because of the great influence from the ipsilateral transmission, a position close to the cochlea would be beneficial for patients with bilateral BC hearing aids.

Platelet-rich plasma in bone repair of irradiated tibiae of Wistar rats / Plasma rico em plaquetas na reparação óssea em tíbias irradiadas de ratos Wistar

PURPOSE: To evaluate the influence of PRP addition on bone repair of circular defects created in irradiated tibiae of rats by histometric analysis. METHODS: Sixty male Wistar rats had the right tibiae irradiated with 30 Gy. After 30 days monocortical defects were created and platelet-rich plasma was applied in 30 rats. In the control group defects were created but not filled. The animals were desanguinated after 4, 7, 14, 21, 56 and 84 days and the tibiae removed for histological processing. RESULTS: There was a tendency in the PRP group to increased bone neoformation from 14-days to 84-days; in the control group increased bone neoformation was not seen after 21 days or later. CONCLUSION: The addition of platelet-rich plasma had a beneficial effect in the initial cellular regeneration period and enhanced bone formation in later periods when compared to control.

OBJETIVO: Avaliar histometricamente a influência do PRP na reparação óssea de defeitos circulares criados em tíbia irradiada de ratos Wistar. MÉTODOS: Sessenta ratos machos tiveram a tíbia direita irradiada com 30Gy. Após 30 dias, defeitos ósseos monocorticais foram criados e PRP foi adicionado em 30 ratos. No grupo controle os defeitos foram criados, mas não preenchidos. Os animais foram sacrificados em 4, 7, 14, 21, 56 e 84 dias e a tíbia removida para processamento histológico. RESULTADOS: Houve uma tendência do grupo PRP mostrar uma neoformação óssea significativamente maior nos períodos de 14 a 84 dias; no grupo controle o aumento da reparação óssea não se manteve após 21 dias. CONCLUSÃO: A adição de PRP mostrou-se benéfica no período inicial de reparação celular e em períodos seqüentes foi estímulo à quantidade neoformação óssea, quando comparado ao controle.

Platelet-rich plasma in bone repair of irradiated tibiae of Wistar rats.

PURPOSE: To evaluate the influence of PRP addition on bone repair of circular defects created in irradiated tibiae of rats by histometric analysis. METHODS: Sixty male Wistar rats had the right tibiae irradiated with 30 Gy. After 30 days monocortical defects were created and platelet-rich plasma was applied in 30 rats. In the control group defects were created but not filled. The animals were desanguinated after 4, 7, 14, 21, 56 and 84 days and the tibiae removed for histological processing. RESULTS: There was a tendency in the PRP group to increased bone neoformation from 14-days to 84-days; in the control group increased bone neoformation was not seen after 21 days or later. CONCLUSION: The addition of platelet-rich plasma had a beneficial effect in the initial cellular regeneration period and enhanced bone formation in later periods when compared to control.

A novel bone conduction implant (BCI): engineering aspects and pre-clinical studies.

Percutaneous bone anchored hearing aids (BAHA) are today an important rehabilitation alternative for patients suffering from conductive or mixed hearing loss. Despite their success they are associated with drawbacks such as skin infections, accidental or spontaneous loss of the bone implant, and patient refusal for treatment due to stigma. A novel bone conduction implant (BCI) system has been proposed as an alternative to the BAHA system because it leaves the skin intact. Such a BCI system has now been developed and the encapsulated transducer uses a non-screw attachment to a hollow recess of the lateral portion of the temporal bone. The aim of this study is to describe the basic engineering principals and some preclinical results obtained with the new BCI system. Laser Doppler vibrometer measurements on three cadaver heads show that the new BCI system produces 0-10 dB higher maximum output acceleration level at the ipsilateral promontory relative to conventional ear-level BAHA at speech frequencies. At the contralateral promontory the maximum output acceleration level was considerably lower for the BCI than for the BAHA.

Bone-anchored titanium implants for auricular rehabilitation: case report and review of literature.

CONTEXT AND OBJECTIVE: Osseointegrated implants have acquired an important role in the prosthetic rehabilitation of patients with craniofacial defects. The main indications are lack of local tissue for autogenous reconstruction, previous reconstruction failure and selection of this technique by the patient. This paper presents a clinical case and discusses indications and advantages of the osseointegrated implant technique for retention of auricular prostheses. TYPE OF STUDY: Case report, Universidade Federal de São Paulo (UNIFESP). METHODS: A female patient received three auricular implants after surgical resection of a hemangioma in her left ear. The time taken for osseointegration of the temporal bone was three months. After fabrication of the implant-retained auricular prosthesis, the patient was monitored for 12 months. RESULTS: The clinical parameters evaluated showed good postoperative healing, healthy peri-implant tissue, good hygiene and no loss of implants. Good hygiene combined with thin and immobile peri-implant soft tissues resulted in minimal complications. Craniofacial implant integration appears to be site-dependent; increasing age affects osseointegration in the temporal bone. The frequency of adverse skin reactions in peri-implant tissues is generally low. CONCLUSION: The surgical technique for rehabilitation using implant-retained auricular prostheses seems to be simple. It is associated with low rates of adverse skin reactions and long-term complications. Prostheses anchored by osseointegrated implants seem to provide better retention than do prostheses supported on spectacle frames, less risk of discoloration through the use of adhesives and better esthetic results than do prostheses anchored in the surgical cavity.

Bone-anchored titanium implants for auricular rehabilitation: case report and review of literature / Implantes osseointegrados de titânio para reabilitação auricular: relato de caso e revisão da literatura

CONTEXT AND OBJECTIVE: Osseointegrated implants have acquired an important role in the prosthetic rehabilitation of patients with craniofacial defects. The main indications are lack of local tissue for autogenous reconstruction, previous reconstruction failure and selection of this technique by the patient. This paper presents a clinical case and discusses indications and advantages of the osseointegrated implant technique for retention of auricular prostheses. TYPE OF STUDY: Case report, Universidade Federal de São Paulo (UNIFESP). METHODS: A female patient received three auricular implants after surgical resection of a hemangioma in her left ear. The time taken for osseointegration of the temporal bone was three months. After fabrication of the implant-retained auricular prosthesis, the patient was monitored for 12 months. RESULTS: The clinical parameters evaluated showed good postoperative healing, healthy peri-implant tissue, good hygiene and no loss of implants. Good hygiene combined with thin and immobile peri-implant soft tissues resulted in minimal complications. Craniofacial implant integration appears to be site-dependent; increasing age affects osseointegration in the temporal bone. The frequency of adverse skin reactions in peri-implant tissues is generally low. CONCLUSION: The surgical technique for rehabilitation using implant-retained auricular prostheses seems to be simple. It is associated with low rates of adverse skin reactions and long-term complications. Prostheses anchored by osseointegrated implants seem to provide better retention than do prostheses supported on spectacle frames, less risk of discoloration through the use of adhesives and better esthetic results than do prostheses anchored in the surgical cavity

CONTEXTO E OBJETIVO: Os implantes osseointegrados adquiriram papel importante na reabilitação protética de pacientes com defeitos craniofaciais. As principais indicações são ausência local de tecidos para reconstrução autógena, falha anterior de reconstrução e opção do paciente. Este artigo apresenta um caso clínico e discute as indicações e vantagens da técnica de implantes osseointegrados para a retenção de próteses auriculares. TIPO DE ESTUDO E LOCAL: Relato de caso clínico, Universidade Federal de São Paulo (UNIFESP). MÉTODOS: Paciente do sexo feminino recebeu três implantes na região auricular após ressecção cirúrgica de hemangioma na orelha esquerda. O tempo de osseointegração no osso temporal foi de três meses. Após a confecção de prótese auricular implanto-suportada, a paciente foi observada por 12 meses. RESULTADOS: Os parâmetros clínicos analisados mostraram boa cicatrização pós-operatória, saúde dos tecidos adjacentes ao implante, boa higiene e nenhuma perda de implantes. A boa higiene combinada a pouca espessura e imobilidade dos tecidos moles perimplantares resulta em poucas complicações. A integração dos implantes craniofaciais parece variar conforme o local, e a idade avançada afeta a osseointegração no osso temporal. A frequência de reações adversas cutâneas nos tecidos perimplantares é geralmente baixa. CONCLUSÃO: A técnica cirúrgica para a reabilitação com próteses auriculares implanto-suportadas parece ser simples e está associada a baixos índices de reações cutâneas adversas e complicações no longo prazo. As próteses ancoradas por implantes osseointegrados parecem proporcionar melhor retenção do que as próteses suportadas nas armações de óculos, menor possibilidade de descoloração pelo uso de adesivos e melhores resultados estéticos do que as próteses ancoradas na cavidade cirúrgica.

Transmission of bone-conducted sound in the human skull measured by cochlear vibrations.

One limitation with the Bone Anchored Hearing Aid (Baha) is too poor amplification for patients with moderate to severe sensorineural hearing losses. Therefore, we investigated if bone conducted (BC) sound transmission improves when the stimulation approaches the cochlea. Also the influence from the squamosal suture on BC sound transmission was investigated. Both sides of the heads on seven human cadavers were used and vibrational stimulation was applied at eight positions on each side with a frequency range of 0.1-10 kHz. A laser Doppler vibrometer was used to measure the resulting velocity of the cochlear promontory. It was found that the velocity of the promontory increases as the stimulation position approaches the cochlea; this was especially apparent at distances within 2.5 cm from the ear canal opening and when the stimulation position was in the opened mastoid. At frequencies above 500 Hz there was on average 10 to 20 dB greater vibrational response at the cochlea when the stimulation was close to the cochlea compared with the normal Baha position. Moreover, even if there were general indications of attenuation of BC sound when passing the squamosal suture, an effect from the suture could not be conclusively determined.

Percutaneous versus transcutaneous bone conduction implant system: a feasibility study on a cadaver head.

OBJECTIVE: Percutaneous bone-anchored hearing aid (BAHA) is an important rehabilitation alternative for patients who have conductive or mixed hearing loss. However, these devices use a percutaneous and bone-anchored implant that has some drawbacks reported. A transcutaneous bone conduction implant system (BCI) is proposed as an alternative to the percutaneous system because it leaves the skin intact. The BCI transmits the signal to a permanently implanted transducer with an induction loop system through the intact skin. The aim of this study was to compare the electroacoustic performance of the BAHA Classic-300 with a full-scale BCI on a cadaver head in a sound field. The BCI comprised the audio processor of the vibrant sound bridge connected to a balanced vibration transducer (balanced electromagnetic separation transducer). METHODS: Implants with snap abutments were placed in the parietal bone (Classic-300) and 15-mm deep in the temporal bone (BCI). The vibration responses at the ipsilateral and contralateral cochlear promontories were measured with a laser Doppler vibrometer, with the beam aimed through the ear canal. RESULTS: Results show that the BCI produces approximately 5 dB higher maximum output level and has a slightly lower distortion than the Classic-300 at the ipsilateral promontorium at speech frequencies. At the contralateral promontorium, the maximum output level was considerably lower for the BCI than for the Classic-300 except in the 1-2 kHz range, where it was similar. CONCLUSION: Present results support the proposal that a BCI system can be a realistic alternative to a BAHA.

Oculo-auriculo-vertebral spectrum: associated anomalies, functional deficits and possible developmental risk factors.

Swedish patients with the oculo-auriculo-vertebral (OAV) spectrum participated in a prospective multidisciplinary investigation. The aims of the study were to describe their systemic and functional defects, especially autism spectrum disorders, and to search for possible etiologic risk factors. Available medical records were studied and the mothers answered a questionnaire on history of prenatal events. A clinical examination evaluating systemic findings, vision, hearing, speech, oral and swallowing function, and neuropsychiatric function, especially autism, was made. Eighteen patients, (11 males, 7 females) aged 8 months to 17 years with OAV were studied. Most frequent systemic malformations included, ear abnormalities (100%), ocular malformations (72%), vertebral deformities (67%), cerebral anomalies (50%), and congenital heart defects (33%). Functional defects consisted of hearing impairment (83%), visual impairment (28%), both visual and hearing impairment (28%), difficulties in feeding/eating (50%), speech (53%), mental retardation (39%), and severe autistic symptoms (11%). Three children were born following assisted fertilization (two intracytoplasmatic sperm injection, one in vitro fertilization), two mothers reported early bleedings, and six (33%) mothers had smoked during pregnancy.

High age at the time of implant installation is correlated with increased loss of osseointegrated implants in the temporal bone.

BACKGROUND: The implant failure rate in temporal bone has been reported to be about 5 to 10% over a 10-year period. A number of our elderly patients have shown increased failure rates over a long time period, which is the reason for the present study. PURPOSE: The aim of the present study was to find out if age is correlated with implant failure and to measure blood flow in implant sites. MATERIALS AND METHODS: The long-time survival of 131 osseointegrated implants installed in the temporal bones of 81 patients was correlated with the age of the patient at the time of installation. The blood flow in 37 fixture installation sites in 22 patients was recorded by means of laser Doppler flowmetry. RESULTS: The mean implant failure rate in the study group was 9.8% after a mean follow-up time of 7.6 years. There was a significant increase of implant failure in patients above 60 years of age. There was further a trend that implants used for the bone-anchored hearing aid were lost to a higher proportion than implants used for bone-anchored episthesis. There was also a trend that female patients lost fewer implants than males. Blood flow in the temporal bone correlated well with the age of the patient in that the highest values were recorded from the youngest patients. CONCLUSIONS: Increasing age affects failures of osseointegrated implants in the temporal bone. Blood flow is higher in the child's temporal bone, a factor that can be of importance to understand why age influences implant survival.

Audiological evaluation and self-assessed hearing problems in subjects with single-sided congenital external ear malformations and associated conductive hearing loss.

Previously, unilateral hearing impairment (UHI) has been considered of little consequence. However, a recent meta-analysis of children with UHI displayed educational and behavioural problems and possible delays of speech and language development. Further, patients with UHI consequently report hearing difficulties. Our study investigated hearing function, possible inner ear protection, and self-assessed hearing problems in 57 subjects aged between 3-80 years with single-sided congenital ear malformations and conductive UHI. Pure-tone thresholds and speech recognition (quiet, noise) were measured, and all patients completed a self-assessment questionnaire. Pure-tone thresholds corresponding to sensorineural function did not significantly differ between the normal (air conduction) and affected ear (bone conduction). However, speech recognition in both quiet and in noise was normal on the non-affected side but significantly worse on the malformed side. A moderate to high degree of self-assessed hearing problems were reported. In conclusion, hearing function in the affected ear was found to be subnormal in terms of supra threshold signal processing. Furthermore, a high degree of hearing difficulty was reported. Therefore, active treatment, surgery, or hearing amplification, might be considered.

Diplopia in orbital fractures: a simple method to evaluate eye motility.

CONCLUSION: This study on eye motility demonstrates a new application of electro-oculography which proved to have a high potential for establishing and diagnosing the cause of diplopia in orbital floor fractures. Electro-oculography is objective and easy to perform even when the restricted eye is covered. The 'uninjured' eye can be used as the reference. Any motility difference between the left and the right eye was easily detected. OBJECTIVE: It is essential in orbital floor fractures to distinguish entrapment from other causes of diplopia. We investigated whether vertical eye motility and restricted elevation can be detected and characterized by means of electro-oculography. MATERIALS AND METHODS: Electronystagmography equipment used for vestibular testing in daily ENT practice was used in a different context. Unilateral mechanical restriction was generated in the test subjects through fixation of one eye bulb. The velocity and range of eye motility of both eyes were measured and compared in 12 healthy test subjects and 7 patients with long-term vertical diplopia after orbital floor fractures. RESULTS: Simulated entrapment was easily detected as a distinct difference between right and left eye motility recordings (p<0.001). Recordings of patients with diplopia differed significantly from those of healthy test subjects with respect to velocity (p<0.05) and range of motility (p<0.05).

Autism spectrum disorder and underlying brain mechanism in the oculoauriculovertebral spectrum.

As part of a multidisciplinary study, the rate of autism spectrum disorder (ASD), learning disability (LD), and brain abnormalities was examined in 20 participants (12 males, 8 females; age range 8mo-17y, mean age 8y 1mo) diagnosed as falling within the oculoauriculovertebral spectrum (OAV). A neuropsychiatric examination was performed, including standardized autism diagnostic interviews. Two individuals met diagnostic criteria for autism, one for autistic-like condition, and five for autistic traits. Four patients had mild LD, three severe LD, two profound LD, and two borderline intellectual functioning. Neuroimaging indicated cerebral abnormalities in more than half of the patients. Abnormalities of white/grey matter were found in more than half of examined individuals; enlargement of ventricles in more than a third. Results indicate that at least a subgroup of ASD may be associated with errors in early embryonic brain development. Awareness of the coexistence of OAV/ASD is important in habilitation care of individuals with OAV.

BAHA in children and adolescents with unilateral or bilateral conductive hearing loss: a study of outcome.

OBJECTIVES: Bilateral BAHAs in adults with bilateral hearing loss (BHL) have proven to be superior to unilateral fitting, in both audiologically measurements and in overall patient satisfaction. There have been no similar studies in children. Furthermore, a recent meta-analysis of children with unilateral hearing loss (UHL) has shown numerous negative consequences. The objectives of the study were to investigate whether fitting of bilateral BAHAs in children with conductive BHL give additional hearing benefits, to investigate the effects of unilateral hearing aids in children with conductive UHL, and to identify different aspects of auditory problems in children with conductive UHL or BHL. STUDY DESIGN: This was a prospective study involving 22 children with either conductive UHL (unaided or with unilateral hearing aid) or conductive BHL (with unilateral or bilateral BAHAs) and 15 controls. METHODS: Baseline audiometry, tone thresholds in a sound field, speech recognition in noise and sound localization were tested without, and with unilateral and bilateral hearing aids. Two questionnaires, MAIS & MUSS and IOI-HA, were completed. RESULTS: Two problem areas were identified in the children with hearing impairment: in reactions to sounds and in intelligibility of speech. An additional BAHA in the children with BHL resulted in a tendency to have improved hearing in terms of better sound localization and speech recognition in noise. Fitting of unilateral hearing aids in the children with UHL gave some supplementary benefit in terms of better speech recognition in noise but no positive effect on ability to localize sound could be detected. Even so, all children fitted with hearing aids - either unilaterally or bilaterally - reported a positive outcome with their devices in the self-assessment questionnaire. CONCLUSIONS: Children with either UHL or BHL displayed several problems within the hearing domain. Fitting of bilateral BAHAs in children with BHL and of a single-sided hearing aid in children with UHL appears to have some supplementary audiological benefits and also renders high patient satisfaction. In order to investigate the possible supplementary effects of hearing aids, a 3-month trial of BAHA on Softband, either unilaterally or bilaterally, may be of value in children with conductive UHL or BHL, respectively.

Retrieved implants from irradiated sites in humans: a histologic/histomorphometric investigation of oral and craniofacial implants.

PURPOSE: The aim of this report was to quantitatively and qualitatively evaluate the tissue response to bone-anchored implants retrieved from irradiated sites in patients. MATERIALS AND METHODS: The material consists of 23 consecutively received Brånemark implants (Nobel Biocare AB, Göteborg, Sweden) placed in pre- or postoperatively irradiated sites. Twenty-two of the 23 implants were suitable for histologic evaluation of undecalcified sections in the light microscope. RESULTS: The oral implants with shorter time in situ demonstrated sparse bone to implant contact with mainly dense connective tissue in the interface. However, for implants with longer time in situ, high amounts of bone-implant contact and bone fill of threads were noted. The mean values of bone-implant contact and bone area within the thread were calculated to 40% (16-94) and 70% (13-96), respectively. The craniofacial implants, with the exception of two implants lined with a capsular formation, demonstrated mature and newly formed bone at the bone-implant interface. The mean value for bone-metal contact was calculated to 45 and 53% for two specimens. The mean value for bone area within the thread ranged from 65 to 88% for three specimens. CONCLUSION; The possibility to achieve bone anchorage of implants in irradiated tissue was supported by the findings in this study. However, due to limited material, conclusions with regard to radiation dose and bone tissue response to implants cannot be stated.