Manoj Komath

Publications of Manoj Komath

• Preparation and analysis of chemically gradient functional bioceramic coating formed by pulsed laser deposition.

  Authors: P Rajesh, C V Muraleedharan, S Sureshbabu, Manoj Komath, Harikrishna Varma

  Journal of materials science. Materials in medicine. 11/2011; 23(2):339-48.

  Bioactive ceramic coatings based on calcium phosphates yield better functionality in the human body for a variety of metallic implant devices including orthopaedic and dental prostheses. In theBioactive ceramic coatings based on calcium phosphates yield better functionality in the human body for a variety of metallic implant devices including orthopaedic and dental prostheses. In the present study chemically and hence functionally gradient bioceramic coating was obtained by pulsed laser deposition method. Calcium phosphate bioactive ceramic coatings based on hydroxyapatite (HA) and tricalcium phosphate (TCP) were deposited over titanium substrate to produce gradation in physico-chemical characteristics and in vitro dissolution behaviour. Sintered targets of HA and α-TCP were deposited in a multi target laser deposition system. The obtained deposits were characterized by X-ray diffraction, fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. Inductively coupled plasma spectroscopy was used to estimate the in vitro dissolution behaviour of coatings. The variation in mechanical property of the gradient layer was evaluated through scratch test and micro-indentation hardness. The bioactivity was examined in vitro with respect to the ability of HA layer to form on the surface as a result of contact with simulated body fluid. It could be inferred that chemically gradient functional bioceramic coating can be produced by laser deposition of multiple sintered targets with variable chemical composition.

• Laser surface modification of titanium substrate for pulsed laser deposition of highly adherent hydroxyapatite.

  Authors: P Rajesh, C V Muraleedharan, Manoj Komath, Harikrishna Varma

  Journal of materials science. Materials in medicine. 05/2011; 22(7):1671-9.

  Biomedical implant devices made out of titanium and its alloys are benefited by a modified surface or a bioactive coating to enhance bone bonding ability and to function effectively in vivo for theBiomedical implant devices made out of titanium and its alloys are benefited by a modified surface or a bioactive coating to enhance bone bonding ability and to function effectively in vivo for the intended period of time. In this respect hydroxyapatite coating developed through pulsed laser deposition is a promising approach. Since the success of the bioactive ceramic coated implant depends mainly on the substrate-coating strength; an attempt has been made to produce micro patterned surface structure on titanium substrate for adherent hydroxyapatite coating. A pulsed Nd-YAG laser beam (355 nm) with 10 Hz repetition rate was used for surface treatment of titanium as well as hydroxyapatite deposition. The unfocussed laser beam was used to modify the substrate surface with 500-18,000 laser pulses while keeping the polished substrate in water. Hydroxyapatite deposition was done in a vacuum deposition chamber at 400 °C with the focused laser beam under 1 × 10⁻³ mbar oxygen pressure. Deposits were analyzed to understand the physico-chemical, morphological and mechanical characteristics. The obtained substrate and coating surface morphology indicates that laser treatment method can provide controlled micro-topography. Scratch test analysis and microindentation hardness values of coating on laser treated substrate indicate higher mechanical adhesion with respect to coatings on untreated substrates.

• Formation of hydroxyapatite coating on titanium at 200◦C through pulsed laser deposition followed by hydrothermal treatment

  Authors: MANOJ KOMATH, P RAJESH, C V MURALEEDHARAN, H K VARMA, R RESHMI, M K JAYARAJ

  Bulletin of Materials Science. 01/2011; 34:389-399.

  Pulsed laser deposition (PLD) has emerged as an acceptable technique to coat hydroxyapatite on titanium-based permanent implants for the use in orthopedics and dentistry. It requires substratePulsed laser deposition (PLD) has emerged as an acceptable technique to coat hydroxyapatite on titanium-based permanent implants for the use in orthopedics and dentistry. It requires substrate temperature higher than 400◦C to form coatings of good adhesion and crystallinity. As this range of temperatures is likely to affect the bulk mechanical properties of the implant, lowering the substrate temperature during the coating process is crucial for the long-term performance of the implant. In the present study, hydroxyapatite target was ablated using a pulsed Nd:YAG laser (355 nm) onto commercially pure titanium substrates kept at 200◦C. The coating thus obtained has been subjected to hydrothermal treatment at 200◦C in an alkaline medium. The coatings were analysed using microscratch test, optical profilometry, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and infrared spectroscopy (FTIR). XRD, EDS and FTIR showed that the as-deposited coating contained amorphous calcium phosphate and the hydrothermal treatment converted it into crystalline hydroxyapatite. The micro-morphology was granular, with an average size of 1 micron. In the microscratch test, a remarkable increase in adhesion with the substrate was seen as a result of the treatment. The plasma plume during the deposition has been analysed using optical emission spectroscopy, which revealed atomic and ionic species of calcium, phosphorous and oxygen. The outcomes demonstrate the possibility of obtaining adherent and crystalline hydroxyapatite on titanium substrate at 200◦C through pulsed laser deposition and subsequent hydrothermal treatment

• Pulsed laser deposition of hydroxyapatite on titanium substrate with titania interlayer.

  Authors: P Rajesh, C V Muraleedharan, Manoj Komath, Harikrishna Varma

  Journal of materials science. Materials in medicine. 01/2011; 22(3):497-505.

  Pulsed laser deposition (PLD) has been used to deposit hydroxyapatite (HA) ceramic over titanium substrate with an interlayer of titania. PLD has been identified as a potential candidate forPulsed laser deposition (PLD) has been used to deposit hydroxyapatite (HA) ceramic over titanium substrate with an interlayer of titania. PLD has been identified as a potential candidate for bioceramic coatings over metallic substrates to be used as orthopedic and dental implants because of better process control and preservation of phase identity of the coating component. However, direct deposition of hydroxyapatite on titanium at elevated temperature results in the formation of natural oxide layer along with some perovskites like calcium titanate at the interface. This leads to easy debonding of ceramic layer from the metal and thereby affecting the adhesion strength. In the present study, adherent and stable HA coating over Ti6Al4V was achieved with the help of an interlayer of titania. The interlayer was made to a submicron level and HA was deposited consecutively to a thickness of around one micron by exposing to laser ablation at a substrate temperature of 400°C. The deposited phase was identified to be phase pure HA by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and inductively coupled plasma spectrometry. The mechanical behavior of coating evaluated by scratch test indicates that the adhesion strength of HA coating was improved with the presence of titania interlayer.

• Calcium phosphate cement as a "barrier-graft" for the treatment of human periodontal intraosseous defects

  Authors: J Rajesh, K Nandakumar, H Varma, Manoj Komath

  Indian Journal of Dental Research. 01/2009;

  Background : Calcium phosphate cements (CPC) are apparently good candidates for periodontal treatment by virtue of their biocompatibility, mouldability and osteoconductivity. However, the clinicalBackground : Calcium phosphate cements (CPC) are apparently good candidates for periodontal treatment by virtue of their biocompatibility, mouldability and osteoconductivity. However, the clinical efficacy in this regard has not been established. This study is aimed at the evaluation of the efficacy of a formulation of CPC in healing human periodontal intraosseous defects in comparison with hydroxyapatite ceramic granules. Materials and Methods : In this clinical study, 60 patients with periodontal defects were divided into 2 test groups and 1 control group. The defect sites in the test groups were repaired with CPC and hydroxyapatite ceramic granules (HAG). Debridement alone was given in the control group. The progress was assessed at 3, 6, 9 and 12 months observation intervals through soft tissue parameters (probing depth, attachment level and gingival recession). Results: CPC showed significantly better outcome. Probing depth reduction values of CPC, HAG and Control at 6 months were 5.40 ± 1.43, 3.75 ± 1.71 and 2.90 ± 1.48, and those at 12 months were 6.20 ± 1.80, 4.5 ± 1.91 and 2.95 ± 1.73. Clinical attachment gain values of CPC, HAG and Control at 6 months were 5.15 ± 1.50, 3.45 ± 1.96 and 2.25 ± 1.52, and those at 12 months were 5.80 ± 2.02, 3.55 ± 2.06 and 2.30 ± 1.78, In both cases the P value was < 0.001 showing high significance. The gingival recession over 12 months, for the CPC group is lesser than that in the HAG group and the value for the control group is marginally higher than both. Soft-tissue measurements were appended by postoperative radiographs and surgical re-entry in selected cases. Conclusions: Calcium phosphate cement is found to be significantly better than hydroxyapatite ceramic granules. The material could be considered as a "barrier-graft".

• Calcium phosphate cement as a "barrier-graft" for the treatment of human periodontal intraosseous defects.

  Authors: J B Rajesh, K Nandakumar, H K Varma, Manoj Komath

  Indian journal of dental research : official publication of Indian Society for Dental Research. 20(4):471-9.

  Calcium phosphate cements (CPC) are apparently good candidates for periodontal treatment by virtue of their biocompatibility, mouldability and osteoconductivity. However, the clinical efficacy inCalcium phosphate cements (CPC) are apparently good candidates for periodontal treatment by virtue of their biocompatibility, mouldability and osteoconductivity. However, the clinical efficacy in this regard has not been established. This study is aimed at the evaluation of the efficacy of a formulation of CPC in healing human periodontal intraosseous defects in comparison with hydroxyapatite ceramic granules. In this clinical study, 60 patients with periodontal defects were divided into 2 test groups and 1 control group. The defect sites in the test groups were repaired with CPC and hydroxyapatite ceramic granules (HAG). Debridement alone was given in the control group. The progress was assessed at 3, 6, 9 and 12 months observation intervals through soft tissue parameters (probing depth, attachment level and gingival recession). CPC showed significantly better outcome. Probing depth reduction values of CPC, HAG and Control at 6 months were 5.40 +/- 1.43, 3.75 +/- 1.71 and 2.90 +/- 1.48, and those at 12 months were 6.20 +/- 1.80, 4.5 +/- 1.91 and 2.95 +/- 1.73. Clinical attachment gain values of CPC, HAG and Control at 6 months were 5.15 +/- 1.50, 3.45 +/- 1.96 and 2.25 +/- 1.52, and those at 12 months were 5.80 +/- 2.02, 3.55 +/- 2.06 and 2.30 +/- 1.78, In both cases the P value was < 0.001 showing high significance. The gingival recession over 12 months, for the CPC group is lesser than that in the HAG group and the value for the control group is marginally higher than both. Soft-tissue measurements were appended by postoperative radiographs and surgical re-entry in selected cases. Calcium phosphate cement is found to be significantly better than hydroxyapatite ceramic granules. The material could be considered as a "barrier-graft".

• Fully injectable calcium phosphate cement--a promise to dentistry.

  Authors: Manoj Komath, H K Varma

  Indian journal of dental research : official publication of Indian Society for Dental Research. 15(3):89-95.

  Calcium phosphate cements (CPC) are self setting and biocompatible bone substitute materials with potential applications in dentistry. However, its clinical use has been challenged by poorCalcium phosphate cements (CPC) are self setting and biocompatible bone substitute materials with potential applications in dentistry. However, its clinical use has been challenged by poor rheological properties. A novel formulation of CPC has been developed, which gives a fully injectable and cohesive paste. This work investigates the suitability of the new "fully injectable calcium phosphate cement" (FI-CPC) for dental applications. The cementing properties, material characteristics, and the rheological properties were tested using a battery of material characteristics methods. The biocompatibility was also evaluated as per ISO 7405. The setting time (20 min) and compressive strength (>11 Mpa) of FI-CPC satisfy the clinical requirements. It underwent setting without any exothermic reaction, keeping good dimensional stability. The cement paste could be extruded through a 18-gauge needle, easily and fully. It showed excellent cohesion when immersed in water. FI-CPC was seen to set into a micro-porous mass of hydroxyapatite, the mineral part of human dentin. It showed good attachment to dentin walls, when filled in tooth perforations. FI-CPC was found non-toxic, non-allergic, non-pyrogenic, and soft-tissue compatible. The study shows that FI-CPC provides a self setting bio-compatible paste with excellent rheological properties for surgical applications. The set cement provides good and stable sealing. The osteoconductive property is an added advantage. FI-CPC proves to be an ideal material for endodontic sealing/filling and periodontic repair.