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FEATURED HANDPIECE ARTICLE:

Applications Of Lasers In Dentistry: A Review

 

 

Applications of Lasers in Dentistry: A Review

 

Author:

Prof (Dr.) Bashir A Mir

Professor,

Dept. of Oral and Maxillofacial Surgery,

Govt. Dental College, Sgr.

 

Co authors:

Dr. Ajaz A Shah

Associate Professor and Head,

Dept. of Oral and Maxillofacial Surgery,

Govt. Dental College, Sgr.

 

Dr. Suhail Latoo

Lecturer

Department of Oral Pathology and Microbiology,

Govt. Dental College, Sgr

 

Dr. Altaf H Malik

Dept. of Oral and Maxillofacial Surgery,

Govt. Dental College, Sgr

 

ABSTRACT

 Lasers were introduced into the field of clinical dentistry with the hope of overcoming some of the drawbacks posed by the conventional methods of dental procedures. Since its first experiment for dental application in the 1960s, the use of laser has increased rapidly in the last couple of decades. At present, wide varieties of procedures are carried out using lasers. The aim of this review is to describe the application of lasers in dental hard tissue procedures. Lasers are found to be effective in cavity preparation, caries removal, restoration removal, etching, and treatment of dentinal sensitivity, caries prevention and bleaching. Based on development in adhesive dentistry and the propagation of minimum intervention principles, lasers may revolutionize cavity design and preparation. 

 Key words: laser, dental hard tissue, adhesive dentistry

 

INTRODUCTION

The use of lasers in dentistry has increased over the past few years. The first laser was introduced into the fields of medicine and dentistry during the 1960s (Goldman et al., 1964). Since then, this science has progressed rapidly. Because of their many advantages, lasers are indicated for a wide variety of procedures (Frentzen and Koort, 1990; Aoki et al., 1994; Pelagalli et al., 1997; Walsh, 2003). Conventional methods of cavity preparation with low- and high-speed handpieces involve noise, uncomfortable vibrations and stress for patients. Although pain may be reduced by local anaesthesia, fear of the needle and of noise and vibration of mechanical preparation remains causes of discomfort. These disadvantages have led to a search for new techniques as potential alternatives for dental hard tissue removal. The aim of this review is to describe the application of lasers in dental hard tissue procedures. 

 

Historical development

The first experiment with lasers in dentistry was reported in a study about the effects of a pulsed ruby laser on human caries (Goldman et al, 1964). The results of that study showed that the effects varied from small 2-mm deep holes to complete disappearance of the carious tissue, with some whitening of the surrounding rim of enamel, indicating extensive destruction of carious areas along with crater formation and melting of dentine. Further work in the 1970’s focused on the effects of neodymium (Nd) and carbon dioxide (CO2) lasers on dental hard tissues. Early researches found that CO2 lasers produced cracking and disruption of enamel rods, incineration of dentinal tubule contents, excessive loss of tooth structure, carbonisation and fissuring and increased mineralization caused by the removal of organic contents (Gimbel, 2000). It was also reported that the use of the CO2 laser was unfavourable because of the loss of the odontoblastic layer (Wigdor et al., 1993).

Therefore, it was concluded that, unless heat-related structural changes and damage to dentinal tissues could be reduced, laser technology could not replace the conventional dental drill. Further advances in laser technology however, have identified acceptable biologic interactions. For example, the Er: YAG laser was tested for its ability to ablate (or vapourise) dental hard tissues (Gimbel, 2000). Enamel and dentine cavities were successfully prepared using the Er: YAG laser. Since then, this laser has been used for caries removal and cavity preparation, soft tissue minor surgery and scaling (Aoki and Watanabe et al., 1998).

 

CLINICAL APPLICATIONS

Cavity preparation

The Er: YAG laser was tested for preparing dental hard tissues for the first time in 1988. It was successfully used to prepare holes in enamel and dentine with low ‘fluences’ (energy (mJ)/unit area (cm2)). Even without water-cooling (Burkes et al., 1992), the prepared cavities showed no cracks and low or no charring while the mean temperature rise of the pulp cavity was about 4.3°C (Rechmann et al., 1998). In 1989, it was demonstrated that the Er: YAG laser produced cavities in enamel and dentine without major adverse side effects. The ablation efficiency was about one order of magnitude lower than for soft tissue. It was then concluded that dentine and enamel removal was very effective with no risk to the pulp (Armengol, 2000; Cavalcanti, 2003) and the ablation rates in enamel were stated to be in the range of 20-50 µm/pulse, and in dentine they were reported to be as high at lower fluences.

Clinically, cavity preparation in enamel results in ablation craters with a white chalky appearance on the surface of the crater (Tokonabe et al., 1999). In dentine, cavity margins are sharp and dentinal tubules remain open without a smear layer. In a clinical study conducted to evaluate the efficiency and safety of the Er: YAG laser for caries removal and cavity preparation in dentine and enamel (Cozean et al, 1997), Class I, II, III, IV and V cavities were prepared for amalgam and composite restorations. It was found that the Er: YAG laser was equivalent to the air rotor in its ability to make cavity preparations in enamel and dentine and remove caries. However, the floor of the preparation was not as smooth as that achieved with the high-speed drill.  

Caries removal

Carious material contains a higher water content compared with surrounding healthy dental hard tissues. Consequently, the ablation efficiency of caries is greater than for healthy tissues. There is a possible selectivity in the removal of carious material using the Er: YAG laser because of the different energy requirement to ablate carious and sound tissues leaving those healthy tissues minimally affected. However, Rechmann et al. (1998) found that selective ablation of carious dentine is difficult with the Er: YAG laser. The ablation thresholds of healthy dentine and carious dentine are different. The ablation threshold of healthy dentine is two times higher than the corresponding threshold of carious dentine.

Therefore, very small fluences (energy (Joules) / area (cm2)) of the Er: YAG laser energy are required to selectively ablate carious dentine. This low fluence will result in low efficiency of the ablation process (Shigetani, 2002). In another in vitro study investigating the effectiveness of caries removal by Er: YAG laser, it was found that the Er: YAG laser ablated carious dentine effectively with minimal thermal damage to the surrounding intact dentine (Aoki and Ishikawa et al., 1998). The laser removed infected and softened carious dentine to the same degree as the bur treatment. In addition, a lower degree of vibration was noted with the Er: YAG laser treatment. However, the study did not address the issue of selective removal of carious tissue and further studies of caries removal using lasers are indicated. 

Restoration removal

The Er: YAG laser is capable of removing cement, composite resin and glass ionomer (Dostalova et al., 1998; Gimbel, 2000). The efficiency of ablation is comparable to that of enamel and dentine. Lasers should not be used to ablate amalgam restorations however, because of potential release of mercury vapour. The Er: YAG laser is incapable of removing gold crowns, cast restorations and ceramic materials because of the low absorption of these materials and reflection of the laser light (Keller et al., 1998). These limitations highlight the need for adequate operator training in the use of lasers.

Etching

Laser etching has been evaluated as an alternative to acid etching of enamel and dentine. The Er: YAG laser produces micro-explosions during hard tissue ablation that result in microscopic and macroscopic irregularities. These micro-irregularities make the enamel surface micro-retentive and may offer a mechanism of adhesion without acid-etching. However, it has been shown that adhesion to dental hard tissues after Er: YAG laser etching is inferior to that obtained after conventional acid etching (Martinez-Insua et al., 2000). These authors attributed the weaker bond strength of the composite to laser-etched enamel and dentine to the presence of subsurface fissuring after laser radiation. This fissuring is not seen in conventional etched surfaces. The subsurface fissuring contributed to the high prevalence of cohesive tooth fractures in bonding of both laser-etched enamel and dentine.

A similar conclusion was drawn from a study that compared shear bond strength (SBS) of composite resin to dentine surfaces following different treatments (Ceballos et al., 2001). These authors reported that acid etched specimens achieved the highest SBS values, while laser treatment showed the lowest SBS results. These findings suggest that extensive fissuring caused by laser treatment and the consequent poor bonding strength may outweigh the putative advantages of laser etching.

Treatment of dentinal hypersensitivity

Dentinal hypersensitivity is one of the most common complaints in dental clinical practice. Various treatment modalities such as the application of concentrated fluoride to seal the exposed dentinal tubules have been tested to treat the condition. However, the success rate can be greatly improved by the ongoing evaluation of lasers in hard tissue applications. A comparison of the desensitising effects of an Er: YAG laser with those of a conventional desensitising system on cervically exposed hypersensitive dentine (Schwarz et al., 2002) showed that desensitising of hypersensitive dentine with an Er: YAG laser is effective, and the maintenance of a positive result is more prolonged than with other agents.

Caries prevention

Several studies examined the possibility of using laser to prevent caries (Hossain et al., 2000; Apel et al., 2003). It is believed that laser irradiation of dental hard tissues modifies the calcium to phosphate ratio, reduces the carbonate to phosphorous ratio, and leads to the formation of more stable and less acid soluble compounds, reducing susceptibility to acid attack and caries. Laboratory studies have indicated that enamel surfaces exposed to laser irradiation are more acid resistant than non-laser treated surfaces (Watanabe et al., 2001; Arimoto et al., 2001).

The degree of protection against caries progression provided by the one-time initial laser treatment was reported to be comparable to daily fluoride treatment by a fluoride dentifrice (Featherstone, 2000). The threshold pH for enamel dissolution was reportedly lowered from 5.5 to 4.8 and the hard tooth structure was four times more resistance to acid dissolution. However, the actual mechanism of acid resistance by laser irradiation is still unclear and studies, particularly in vivo, to test those claims are required.

Bleaching

The objective of laser bleaching is to achieve an effective power bleaching process using the most efficient energy source, while avoiding any adverse effects (Sun, 2000). Power bleaching has its origin in the use of high-intensity light to raise the temperature of hydrogen peroxide, accelerating the chemical process of bleaching. The FDA approved standards for tooth whitening has cleared three dental laser wavelengths: argon, CO2 and the most recent 980-nm GaAIAs diode. There are no reports at present about the use of the Er: YAG laser in bleaching techniques. The wavelength of the Er: YAG laser may be unsuitable for the procedures, but it is a further area that could be explored.

CONCLUSION

The Er: YAG laser has been found to have applications in areas such as cavity preparation, removal of caries and restorations, and etching of enamel. However, the advantages as well as limitations of the Er: YAG laser treatments have not yet been fully documented. There appear to be windows of opportunity for the Er: YAG laser in a range of dental applications. Lasers may revolutionise cavity design and preparation based on development in adhesive dentistry. 

REFERENCES

Aoki A, Ando Y, Watanabe H and Ishikawa I (1994). In vitro studies on laser scaling of sub-gingival calculus with an erbium: YAG laser. J Periodontal, 65: 1097 – 1106

 

Aoki A, Ishikawa I, Yamada T, Otsuki M, Watanabe H, Tagami J, Ando Y and Yamamoto H (1998). Comparison between Er: YAG laser and conventional technique for root caries treatment in nitro. J Dent Res, 6: 1404-1414.

 

Aoki A, Watanabe H and Ishikawa I (1998). Er: YAG clinical experience in Japan: review of scientific investigations. SPIE, 3248: 40-45.

 

Apel C, Schafer C and Gutknecht N (2003). Demineralization of Er: YAG and Er,Cr: YSGG Laser-Prepared Enamel Cavities in vitro. Caries Res, 37: 34-37.

 

Arimoto N, Suzaki A, Katada H and Senda A (2001). Acid Resistance in Lased Dentine. 6th International Congress on Lasers in Dentistry, 61-62.

 

Armengol V, Jean A and Marion D (2000). Temperature rise during Er: YAG and Nd: YAP laser ablation of dentine. J Endodon, 26(3): 138 –

141.

 

Burkes EJ, Hoke J, Gomes E and Wolbarsht M (1992). Wet versus dry enamel ablation by Er: YAG laser. J Prosthet Dent, 67: 847-851.

 

Cavalcanti BN, Lage-Marques JL and Rode SM (2003). Pulpal temperature increases with Er: YAG laser and high-speed handpieces. J Prosthet Dent, 90: 447-451.

 

Ceballos L, Osorio R, Toledano M and Marshall GW (2001). Microleakage of composite restorations after acid or Er: YAG laser cavity treatment. Dental Materials, 17: 340-346.

 

Cozean C, Arcoria CJ, Pelagalli J and Powell GL (1997). Dentistry for the 21st century? Erbium: YAG laser for teeth. J Am Dent Assoc, 128: 10801087.

 

Dostalova T, Jelinkova H, Kucerova H, Krejsa O, Hamal K, Kubelka J and Prochazka S (1998). Noncontact Er: YAG Laser Ablation: Clinical Evaluation. J Clin Laser Med Surg, 16(5): 273

 

Featherstone JDB (2000). Caries detection and prevention with laser energy. Dental Clinics of North America, 44(4): 955-969.

 

Frentzen M and Koort HJ (1990). Lasers in dentistry: new possibilities with advancing laser technology? Int Dent J, 40: 323 – 332

Gimbel CB (2000). Hard tissue laser procedures. Dental Clinics of North America, 44(4): 931-953.

 

Goldman L, Hornby P, Meyer R and Goldman B (1964). Impact of the laser on dental caries. Nature, 203: 417.

 

Hossain M, Nakamura Y, Kimura Y, Yamada Y, Ito M and Matsumoto K (2000). Caries-Preventive Effect of Er: YAG Laser Irradiation with or without Water Mist. J Clin Laser Med Surg, 18(2): 61-65.

 

Keller U, Hibst R, Geurtsen W, Schilke R, Heidemann D, Klaiber B and Raab WHM (1998). Erbium: YAG laser application in caries therapy. Evaluation of patient perception and acceptance. J Dent, 26: 649-656.

 

Martinez-Insua            A, Dominguez LS, Rivera FG and Santana-Penin UA (2000). Differences in bonding to acid-etched or Er: YAG – laser – treated enamel and dentine surfaces. J Prosthet Dent, 84: 280-288.

 

Pelagalli J, Gimbel CB, Hansen RT, Swett A and Winn II DW (1997). Investigational Study of the Use of Er: YAG Laser Versus Dental Drill for Caries Removal and Cavity Preparation – Phase I. J Clin Laser Med Surg, 15(3): 109 – 115.

 

Rechmann P, Goldin DS and Hennig T (1998). Er: YAG lasers in dentistry: an overview. SPIE, 3248: 0277-0286.

 

Schwarz F, Arweiler N, Georg T and Reich E (2002). Desensitising effects of an Er: YAG laser on hypersensitive dentine, a controlled, prospective clinical study. J Clin Periodontol, 29: 211-215.

 

Shigetani Y, Okamoto A, Abu-Bakr N and Iwaku M (2002. A study of cavity preparation by Er: YAG laser – observation of hard tooth structure by laser scanning microscope and examination of the time necessary to remove caries. Dent Mater J, 21(1): 20 – 31.

Sun G (2000). The role of lasers in cosmetic dentistry. Dental Clinics of North America, 44(4): 831-850.

 

Tokonabe H, Kouji R, Watanabe H, Nakamura Y and Matsumoto K (1999). Morphological changes of human teeth with Er: YAG laser irradiation. J Clin Laser Med Surg, 17(1): 7-12.

 

Watanabe H, Yamamoto H, Kawamura M, Okagamv Y, Kataoka K and Ishikawa I (2001). Acid Resistance of the Human Teeth Enamel Irradiated by Er: YAG Laser. 6th International Congress on Lasers in Dentistry, 68-69.

Walsh LJ (2003). The current status of laser applications in dentistry. Aust Dent J, 48(3): 146

 

Wigdor H, Abt E, Ashrafi S and Walsh Jr JT (1993). The effect of lasers on dental hard tissues. J Am Dent Assoc, 124: 65-70. 

 

About the Author

Health and Medical Equipment Financing

The medical field has undergone contact changes and new advancements have been made in health and medical equipment. However these equipments are too costly to buy. Even a dental chair in a dentist’s clinic may cost more. Therefore health and medical equipment financing is essential to acquire the necessary equipment.

Dental equipment financing is one of the types of essential health and medical equipment financing that helps to buy latest cavity filling equipment or advanced whole mouth imaging system. Dental equipments become more advanced nowadays which in turn costs you more. Since they are indispensable for your career you need to buy these. However you can get financial help from some of the genuine financing companies that offer low interest loans.

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Laboratory equipments like analytical instruments, evaporator, microscope, autoclaves and sterilizer, incubator, blood analyzing equipment are indispensable in the medical field. Nay health care institute requires these types of equipments for diagnosing any diseases. However the cost of these equipments is extremely high and so health and medical equipment financing is the only way to acquire these items.

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Some of the legitimate financing companies offer health and medical equipment financing at reasonable rate of interest. You can submit an online application to get fast approval of the loan amount. There is no cumbersome procedures and delayed responses and so you can get the financial help easily at any time you want.

About the Author

Chris Fletcher is an Account Executive at a leading equipment financing company http://www.crestcapital.com/Catalog/ providing equipment leasing in all 50 states. Chris is a frequent contributor to print as well as online publications, and is the author of a blog on commercial financing topics.

How to Find a Good Dentist

Finding the dentist who is right for you and your family is key to establishing and preserving excellent oral health. It’s not wise to pick a dentist out of the phone book or solely based on insurance coverage. Although the search for the right dentist might take some time and some effort, the results (better health and progress toward the perfect smile) make it all worthwhile.

The best way to find a good, reputable general dentist is by referral from a friend or family member. If you’re seeking a specialist, try your family dentist for the best referral.

But what if you don’t have a regular dentist? Perhaps you’ve moved recently to a new neighborhood, your prior practitioner has retired, or like many Americans, you’ve simply put off going to the dentist for so long that you realize you don’t have a dentist.

Of course, it’s possible that you don’t fall into any of these categories. It’s conceivable that you have a skilled dentist committed to his or her patients and that you are delighted with the quality of care he or she provides. Of course, in that case, don’t recommend that you blithely switch practitioners simply for the sake of change.

Whether you’re satisfied with your current dentist, reading this article should raise some interesting questions for you to consider. You may realize that your current dentist is the best choice for you. Conversely, you might decide it’s time to do some research and find the dentist who’s best equipped to help you with your present needs.

It’s important to mention that individual preferences play a large part in what is, in the end, a personal choice. The dentist who has treated your neighbor for twenty years and “walks on water” as far as your neighbor is concerned might be wrong for you. It isn’t necessarily a question of competence, but one of style, interpersonal dynamics, and relevance for particular health needs. Nevertheless, asking your neighbor for a referral is an ideal place to start your search. After all, a fine dentist will create great word of mouth.

You might also ask for referrals from others who have steered you right in the past. Consider consulting coworkers, cousins, your pastor, your gym workout buddy, your fellow fire department volunteers, or anyone whose judgment you trust and who lives or works within a reasonable distance of the dentist’s office.

Finally, surfing the internet will introduce you to a myriad of dental sites and directories. These sites offer information on various dental procedures as well as lists of local dentists. Remember to examine specific qualifications like special experience and teaching appointments. Don’t forget to consider how convenient the dentist’s location is to your home or work. When you ask for a referral, ask some or all the following questions.

. How long have you been treated by Dr. Houston Dentist?
. How did you learn about Dr. Houston Dentist?
. Is insurance coverage your main consideration?
. How helpful are the hygienist and other office personnel?
. Why did you change from your previous dentist?
. How long does it take to get an appointment with Dr. Houston Dentist?
. What is Dr. Houston Dentist’s best quality as a dentist?
. What, if anything, about Dr. Houston Dentist’s practice annoys you?

These questions all call for subjective answers, and that’s the point. Your neighbor’s criteria might be (and probably are) different from yours. For example, insurance coverage may factor heavily in some people’s decisions, whereas others might have particular health needs or scheduling needs to consider. Speak with people you trust and you’ll quickly see just how subjective the entire process truly is.

About the Author

For information, visit
Houston Dentist
.
SoftDental (
www.softdental.com
) is
Houston’s Top Cosmetic Dentistry
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Dental Handpiece

dental handpiece

There are disclosed dental handpieces which comprises means at one end of the handpiece to mount a dental implement, a drive train arranged within the handpiece and extending to the implement-end in order to operate the dental equipment, a light source arranged within the handpiece, and a light guide extending from the light source to a position adjacent to the implement-end of the handpiece for directing light to a treatment region adjacent to the dental autoclave, the light guide being arranged within the handpiece and along side the drive train.

BRIEF DESCRIPTION OF THE PRIOR ART

A handpiece of the above general kind is known from German Gebrauchsmuster No. 69 40 204. In this known handpiece a fibre-optic light guide runs inside a flexible hose, which also contains media lines for water and/or air, from one supply member, which is arranged at the end of the handpiece remote from the tool, on the outside along the handpiece as far as the tool end of the handpiece. For the purpose of rendering possible a partially mutual torsion between handpiece and supply member the hose has a certain overlength. The picking-up and holding of the handpiece and also its handling in respect of the patient is made very difficult, in that the hose runs on the outside on the handpiece.

OBJECT OF THE INVENTION

The invention seeks to provide a dental high speed handpiece of the general kind referred to above i.e having a drive train extending within the handpiece, in which the arrangement of a light guide (which conveys light to a dental treatment region adjacent to the dental implement) is such that the curing light guide does not provide any hindrance or difficulties in manipulating the handpiece in service.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a first embodiment of dental handpieces according to the invention;

FIG. 2 is a section taken on the line II–II in FIG. 1;

FIG. 3 is a cutaway section of the handpiece according to FIG. 1 in a sectional plane twisted in respect of FIG. 1;

FIG. 4 is a sectional view of a modification to the embodiment of FIG. 1;

FIG. 5 is a section taken on the line V–V in FIG. 4; and

FIG. 6 is an enlarged illustration of the circled item VI in FIG. 5.

About the Author

dental handpieces dental autoclave curing light