Objective: The aim of the study was to evaluate the clinical outcomes of oral implant treatment provided at the School of Dentistry, University of Otago from 1989 to 2005. Methods: Oral implant patients (n=320) with 586 implants were identified and invited to attend for a clinical examination. Implant demographics of all the patients were extracted from the files. Implant demographics of the examined and unexamined patients were compared to assess if the examined patients were representative of the total group. One hundred and three patients with 214 implants agreed to attend for an examination. In the clinical examination full mouth plaque scores, probing depths, bleeding on probing and suppuration were measured. In addition, around implants recession and width of keratinized gingiva were also recorded. For the radiographic examination, baseline radiographs and radiographs taken at the time of examination were digitized and compared to measure the amount of bone lost or gained around implants using NIH Image J software. Results: There were equal numbers of males and females with a mean age of 46.3 � 15 years at the time of implant placement. The smoking history at the time of examination was recorded, 56% of the patients were non-smokers, 37% former smokers, and 7% were current smokers. More than half of the implants (56%) were placed in the anterior region. Based on the type of implant system, 79% were Branemark implants, 10% Straumann, 6% Southern implants and 4% were unknown. Most of the patients (64%) had implant-supported crowns, 19% had fixed denture prostheses, and 17% had implant-supported overdentures. The overall implant survival rate was 97.7% with five implants lost (2.3%) and 8 implants treated for peri-implantitis (3.8%). The mean PD around implants was 2.3mm (SD 0.6mm), mean recession was 0.5mm (SD 0.8mm) and mean attachment level of 2.8mm (SD 0.9mm). Probing depths [greater than or equal to] 4mm with BOP were recorded around implants in 8.9% of patients. The mean full mouth plaque score was 30% while mean plaque score around implants was 15.9%. The average bone loss around implants was 0.3mm (SD 0.8). Maximum bone loss observed was 2.9 mm. Conclusion: The prevalence of peri-implant inflammation and implant survival rates in this group of patients appeared comparable to that reported in the literature. The prevalence of peri-implant lesions was low in the group of patients examined.

Doctor of Philosophy (PhD) / An in-depth, longitudinal study of the speech and oral language development of eight infants with a profound hearing loss who receive early interventions focused on developing their auditory, speech and oral language capacity is presented in this thesis. Infants were tracked for two years, during the period when they are changed from a hearing aid to a cochlear implant. All infants in this study had their hearing loss identified early and were fitted with hearing aids between 1 and 7 months of age and received their cochlear implant between 8 and 16 months of age. They attended a number of different auditory-verbal early intervention programs (depending on where they lived) all of which focused on developing speech and language skills through listening. Attendance at their particular early intervention program at least once a week was in addition to weekly attendance the Sydney Cochlear Implant Centre for therapy and audiological services. A broad range of measures has been used to track the infants’ acquisition of oral language skills, including measures of communicative intention, pre-speech and speech development, and oral language development. Despite a wide range of individual differences across the group of infants, the results suggest some general trends. In the area of communicative intent most infants followed typical development patterns in terms of both the types (e.g. requesting, answering etc) and forms (gestural, vocal, verbal) used, but they showed delays in their frequency of usage of these types and forms. For speech development the infants demonstrated typical speech skills by 18-months post-cochlear implantation in the areas of consonant inventories, severity of phonological involvement (speech intelligibility) and phonological process development, but they showed delays in vowel and consonant acquisition. Finally, for language development the infants were delayed relative to typical development at 18 months post-implantation. The findings support and extend previous studies which have demonstrated the benefits of early intervention for communication development in infants with hearing loss (Calderon & Naidu, 2000; Mayne, Yoshinaga-Itano & Sedey, 2000; Moeller, 2000; Yoshinaga-Itano & Apuzzo, 1998). However, the delays in the oral communication skills of the infants in the current study suggest that more intensive long-term intervention is required if the infants are to attain typical oral speech and language development. The findings capture the complexity of early oral language development, which has been lacking in previous studies of infants with significant hearing loss, receiving a cochlear implant (Dettman, Briggs, & Dowell, 2005; Houston, Ying, Pisoni, & Iler Kirk, 2003; Schauwers, Gillis, Daemers, De Beukelaer, & Govaerts, 2004). The present data also provide some limited support for earlier implantation, that is, before 12 months of age, as the infants made little progress in oral language development while using hearing aids. The reduced amount of auditory signal available to them prior to implantation may be the determining factor in their inability to follow typical rates and patterns of development. However, rates of development with the implant were not straightforward and further research on this population is needed. Universal neonatal screening programs for hearing loss will potentially provide a larger population of early identified infant for future research. This will create the opportunity for large scale, prospective, longitudinal, studies examining the acquisition of speech and oral language development. Limitations of this study, tracking the early stages of speech and language development over a two year period are identified. Future studies are needed to follow the infants for a longer time to determine if their rate of development is sufficient for them to catch up in areas of delay and maintain their performance in areas where they match their typically developing peers.

Objectives: To compare the osseointegration of conventionally and immediately restored tapered implants in a split-mouth animal model, and to compare different methods of analysis for measuring osseointegration. Materials & Methods: Twenty tapered implants were placed in the posterior mandibles of ten sheep, three months after premolar extractions. Ten control implants were placed and were restored after three months submerged healing. Ten test implants were placed on the contralateral side at this time and immediately restored. Animals were sacrificed after a further three months healing. Resonance frequency analysis (Implant Stability Quotient, ISQ), and standardized radiographs were taken at all stages. Alveolar bone height relative to the implant shoulder was measured on digitized radiographs. Histomorphometric and micro-Computed Tomograph ([mu]CT) morphometric analysis for Bone-to-Implant Contact (BIC) and Bone Density (BD) were performed. Radiographic, stability and morphometric measurements were compared statistically. Results: Only three (30%) of conventionally restored and two (20%) immediately restored implants survived (p = 0.74). Mean crestal bone level after three months loading differed significantly (control 5.3 � 0.9 mm versus test 0.9 � 1.3 mm; p = 0.02). Control implants lost more crestal bone over three months than test implants but this was not statistically significant (3.5 � 1.0 mm versus 0.7 � 1.0 mm; p = 0.06). The test group showed a higher mean ISQ value (85.4 � 6.9) compared to the control group (72 � 14.4; p = 0.349). Both groups showed a slightly reduced stability during the loaded period. This was more marked for the test group but not statistically significant (-0.5 � 3.8 ISQ versus -4.35 � 6.6 ISQ; p = 0.8). A statistically significant negative correlation was found between the loss of crestal bone and ISQ with loading (Pearson�s coefficient of correlation r = -0.473 p = 0.026). Both groups showed a statistically significant difference in BIC for both histomorphometric analaysis (HMA); p = 0.039 and [mu]CT morphometric analysis; p = 0.013. When the two forms of morphometric analysis were compared, HMA and [mu]CT morphometric analysis differed significantly for both BIC (p = 0.05) and BD (p = 0.048). However, a statistically significant correlation was found between the two measuring techniques, for both BIC (r = 0.335 p = 0.013) and BD (r = 0.439 p = 0.01). Conclusions: The placement of wide-bodied 3i Osseotite NT[TM] tapered implants into sheep mandible resulted in high failure rate regardless of the loading protocol. The sheep mandibular model may be inappropriate as a model for evaluation of immediate loading, and to test implants which are designed for soft bone. Further investigations are needed to look into the variations in bone microstructure along with their impact on the mechanics of implant-bone union. Although a statistically significant difference was found between the two measurement techniques, a positive correlation was found between HMA and [mu]CT morphometric analysis suggesting non-invasive methods may have a potential in assessing osseointegration. Further research is required to optimize the variables in [mu]CT analysis, such as, voltage, filters, and thresholding to minimize artifacts and to maximize bone contrast when titanium implants are present.

Pedicle screw breakage and loosening remain as clinical complications of short segment instrumentation procedures for spinal stabilization. This study has directly visualized and measured elastic, plastic and total vertebral pedicle trabecular bone full-field strains in the regions immediately surrounding the pedicle screw during pedicle screw insertion by utilizing functional microCT imaging and digital volume correlation. Human, porcine and polyurethane foam samples were analyzed and compared. Analysis showed that when osteoporotic human, normal human and porcine pedicle trabecular bone samples were compared, osteoporotic samples showed higher peak plastic strains and greater variability of these strains from their means. This suggests that osteoporotic human samples are non-uniformly elastic and plastic, while normal human and porcine samples are more uniformly elastic and plastic throughout the trabecular structure. PU-foams are not appropriate as models for pedicle trabecular bone in the in vivo environment since strain results showed dissimilar plastic and elastic strain magnitudes than human and porcine pedicle trabecular bone. This study may aid in the development of performance criteria for new PU-foams and improved pedicle screw designs. / Graduation date: 2004

The current study sought to examine predictors of language acquisition for deaf children who received cochlear implants in a large, multi-center trial. General maternal sensitivity as well as two specific types of maternal sensitivity, cognitive and linguistic stimulation, were all evaluated in relation to speech production. Characteristics of the family and child (e.g. maternal education, family income, age at implantation, etc.) were also evaluated. The hypotheses tested were: 1) child age at implantation and gender, maternal education, and family income were expected to predict speech production across 6 and 12 months post-implantation, 2) both Cognitive and Linguistic Stimulation were expected to predict the growth of speech production at 6 and 12 months post-implantation, and 3) Cognitive and Linguistic Stimulation were expected to predict speech production above and beyond that predicted by general Maternal Sensitivity. Results indicated that, of the demographic variables, only child age at implantation was a significant predictor of speech production. Cognitive and linguistic stimulation were significantly associated with the development of speech production in the first year following activation of the implant. Furthermore, these important maternal behaviors accounted for gains in speech production beyond that accounted for by general maternal sensitivity. These findings have several clinical implications, including the development of formalized training for parents of children who receive cochlear implants.

<p>Objectives: Temperature changes along an implant body have not been widely studied. The objectives of this in vitro study were (i) to establish if the temperature of the abutment influences the temperature of the implant surface, (ii) to establish the temperature transmission from abutment to implant body, and (iii) to establish for what abutment temperature the critical time/temperature threshold of 47oC for 1 minute at implant level is reached.</p>

Cochlear implants (CIs) provide coarse representations of pitch, which are adequate for speech but not for music. Despite increasing interest in music processing by CI users, the available information is fragmentary. The present experiment attempted to fill this void by conducting a comprehensive assessment of music processing in adult CI users. CI users (n =6) and normally hearing (NH) controls (n = 12) were tested on several tasks involving melody and rhythm perception, recognition of familiar music, and emotion of recognition in speech and music. CI performance was substantially poorer than NH performance and at chance levels on pitch processing tasks. Performance was highly variable, however, with one individual achieving NH performance levels on some tasks, probably because of low-frequency residual hearing in his unimplanted ear. Future research with a larger sample of CI users can shed light on factors associated with good and poor music processing in this population.

Cochlear implants (CIs) provide coarse representations of pitch, which are adequate for speech but not for music. Despite increasing interest in music processing by CI users, the available information is fragmentary. The present experiment attempted to fill this void by conducting a comprehensive assessment of music processing in adult CI users. CI users (n =6) and normally hearing (NH) controls (n = 12) were tested on several tasks involving melody and rhythm perception, recognition of familiar music, and emotion of recognition in speech and music. CI performance was substantially poorer than NH performance and at chance levels on pitch processing tasks. Performance was highly variable, however, with one individual achieving NH performance levels on some tasks, probably because of low-frequency residual hearing in his unimplanted ear. Future research with a larger sample of CI users can shed light on factors associated with good and poor music processing in this population.

El objetivo de este estudio experimental es evaluar si la gammagrafía ósea (GO) es un método válido para cuantificar la actividad metabólica ósea que se produce alrededor de diferentes superficies implantarias durante el proceso de oseointegración "in vivo", y establecer si existe relación entre el nivel de actividad gammagráfica y el porcentaje de contacto hueso-implante. Material y Método: Se han utilizado 12 conejos New Zealand White a los que se colocaron un total 24 implantes MkIII (Nobel Biocare, Goteborg, Suecia), 12 de superficie mecanizada y 12 de superficie TiUnite®, uno tibial y uno femoral en cada animal de forma aleatoria. Preoperatoriamente y en intervalos de 15, 45, 75, 105 días del postoperatorio se realizaron exploraciones mediante GO (planar y con colimador "pinhole") con Tc99MDF (185 mBq) calculándose unos Índices de Actividad gammagráfica (IA= actividad área de estudio/ actividad área control) de las zonas en las que se localizaban los implantes. Se obtuvieron 240 índices de actividad que se relacionaron con las variables: tiempo, tipo de superficie y sus posibles interacciones. Cuando los IA registrados presentaron una cifra semejante a la que mostraban en las GO preoperatorias se procedió a eutanasiar los animales y se procesaron los especimenes según el protocolo de laboratorio con el fin de calcular los porcentajes de contacto hueso-implante mediante Microscopio Electrónico de Barrido (MEB) calculando las correlaciones entre IA y porcentaje de contacto para las dos superficies estudiadas. Los 240 AI fueron procesados estadísticamente para evaluar los resultados (SAS® v8.0 for windows, SAS Institute Inc., Cary, EE.UU.) con un &#945;= 5%. Resultados: - Existe mayor actividad ósea, independientemente de la localización anatómica (tibial o femoral), alrededor de los implantes mecanizados en la primera GO posoperatoria (p=0.0260 pinhole, p=0.0375 planar).- El valor máximo en todos los casos se registró en la primera GO postoperatoria declinando gradualmente, con lo que registra una curva cuya morfología (independientemente de la localización anatómica y el tipo de superficie) se repite en todos los animales de estudio.- La actividad globalmente evaluada fue menor a nivel tibial independientemente de la superficie (p=0.0001).- Comparando el porcentaje de contacto en la interfase hueso-implante al final del estudio, no se observaron diferencias estadísticamente significativas. - La correlación entre la mayor actividad gammagráfica y el porcentaje de contacto solo pudo ser evidenciada entre la superficie mecanizada y los IA obtenidos en la exploración realizada con "pinhole". Discusión:La GO es un método utilizado para evaluar la actividad osteoblástica y por lo tanto la aplicación en implantología puede ser útil, como han demostrado otros autores. En nuestro studio ha sido efectiva para comparer la actividad generada por los dos tipos de superficie implantológicas, encontrándose que la mayor actividad no se correlaciona con la superficie más bioactive (TiUnite®) ni con un mayor porcentaje de contacto óseo analizado mediante MEB a los 3 meses. Este aspecto no ha sido nunca estudiado previamente aunque otros autores se han interesado por este método diagnóstico como un medio de estudio de la actividad osteoblástica generada por un implante dental.Este resultado puede ser debido a que la superficie mecanizada crea una mayor reacción inflamatoria añadida al proceso de la oseointegración, o a que se require un mayor trabajo biológico para conseguirla. Se precisan más estudios para confirmar esta hipótesis. Respecto al porcentaje de contacto hueso-implante a los 3 meses no existe diferencia estadísticamente significativa probablemente porque las superficies bioactivas se diferencian más en los casos de baja calidad ósea y en el periodo temprano de la oseointegración pero no cuando este proceso ya ha sido completado. Conclusiones: La GO es un método eficaz para cuantificar la actividad ósea periimplantaria generada por diferentes superficies y permite establecer comparaciones entre ellas. Los porcentajes de contacto óseo se igualan con el tiempo en las dos superficies estudiadas. Solo existe correspondencia entre actividad gammagráfica y porcentaje de contacto para la gammagrafía con colimador pinhole. / "Technetium 99-MDP scintigraphy as a method to evaluate osteoblastic activity around implants. Comparison between machined and TiUnite® surfaces in rabbit model".Work hypothesis: 1- the scintigraphy is an approach to study the osseous integration process and allows to differentiate between surfaces biologic response. 2- There is a relation between scintigraphic activity and quantity of bone-implant contact. Materials and Methods: 24 implants (MKIII 10 x 3.75) where installed in 12 New Zealand rabbits, were (12 in femur, 12 in tibia) with different surfaces (machined or TiUnite®). Two kind of scintigraphy (185 mBq of Tc99MDP tracer) were performed one week before the surgery and then every 15 days, 1, 2, 3 months (1 planar and 2 pinhole collimator: 1 in femur, 1 in tibia on the same leg) on each rabbit. AI was calculated (AI= count pixels in implant region/ count in control leg in the same region). When the IA was similar to the baseline, the animals were sacrificed.The 240 AI was processed statistically to evaluate the results (SAS® v8.0 for windows, SAS Institute Inc., Cary, EE.UU.) with an &#945;= 5%. Results:- We found more osseous activity, independent on the anatomic place (tibia or femur), around machined implants in the first post-op scintigraphies (p=0.0260 pinhole, p=0.0375 planar).- Global activity was less in tibia than in femur independent on the surface (p=0.0001).- Comparing the percentage of implant bone contact at the end of the study, there was no statistically difference.Discussion:In our study scintigraphy has been effective to compare the activity generated by two types of implant surfaces, but the results demonstrate that more osseous activity around implant not correlates with a better bioactive surface (TiUnite®) or a major percentage of bone contact analyzed by SEM at 3 months. This aspect never has been studied before even though other authors are interested about this kind of diagnostic technique to study the osteoblastic activity at the implant site.It can be caused because machined surface create greater reaction to foreign body, and more studies must be done to confirm these hypothesis.Respect to the bone-implant percentage there is no statistically differences probably because the bioactive surfaces are better in the poor bone quality and in the early period of osseointegration but not at the end of the process.Conclusions:1- Scintigraphy (planar or pinhole) is a diagnostic technique useful to evaluate metabolic activity around implants in animal model.2- The gammagraphic activity descrives a curve characterized by a significant increase in the first post-op exam, and gradually falloff and returned to pre-implant levels at about 3 months.3- We can consider the duration of the osseointegration process is equivalent to the time that scintigraphy is approximately the same as the pre-op period, and is the same for the two implant surfaces.4- There is no differences respect the time necessary of osseointegration related on location.5- A greater gammagraphyc activity not correlates with a greater percentage of bone-implant contact.

Dos grupos de pacientes (16 en total): Prelinguales y postlinguales.Dos tipos diferentes de implantes cocleares (I.C.): Los monocanales de House fabricados por la 3M y el multicanal de Clark comercializado por Nucleus.La valoración de los resultados se efectuó con las siguientes pruebas :- Umbrales audiometricos - Capacidad de discriminación (De sonidos ambientales y del lenguaje)- Ayuda en la lectura labial y Beneficios en la emisión de la propia voz- Posibles efectos secundariosConcluimos que:1) Resultados globales muy superiores del I.C. multicanal, respecto al monocanal2 Pobres resultados en los prelinguales con ambos tipos de I.C.3) Umbrales audiométricos algo mejores en los multicanales 4) Los dos grupos de pacientes mejoraron claramente en la emisión de la voz, dándole una buena entonación.5) Los dos grupos mejoraron la capacidad de lectura labial.6) Ambos discriminan sonidos ambientales, siendo la capacidad del multicanal superior.7) Capacidad de DiscriminaciónLa ganancia es muy superior en el multicanal. Los fonemas vocálicos en los monocanales, presentan un 53,5% de aciertos y las consonantes el 36,4%. En los multicanales son de un 96% y un 72.3% respectivamente. En la prueba de monosílabas los monocanales solo tienen un 0,5% y los multicanales un 31,3%. Los bisílabas, en listas de 4 bisílabos y en silencio, el monocanal presenta un 50,8% de aciertos y el multicanal el 86,1%, aunque en presencia de ruido ambiental de 10 Db en la relación señal ruido, cae dicha capacidad de discriminación, a 30,6% y 68,3% respectivamente. En listas abiertas de bisílabas las discriminaciones son de un 26.4% para el monocanal y de un 70,3% para el multicanal..El tanto por ciento de discriminación de palabras en frases comunes para el monocanal y multicanal, presentada solo con el I.C. son de 1,4% y 57,1% respectivamente, solo con lectura labial, era del 74,2% y del 80,3%. Uniendo la lectura labial al empleo del I.C. mejoraban claramente, pasando del al 82,8% los monocanales y al 95% los multicanales. 8) El test promontorial: Valor relativo para predecir resultados de I.C.9) No se produce degeneración del nervio acústico por la estimulación continuada.10) No hemos encontrado efectos secundarios importantes tras la implantación (ruptura del electrodo en un monocanal y un caso de tics faciales).