"CARIES REMOVAL PROCEDURE AND RESULTING EQUIPMENT".

The present Invention Patent refers to the caries removal procedure through cavity preparation with a rotary equipment of ultra-low rotation, based upon research done during three years to achieve the Master degree in Biomedical Engineering title, defended in November 10 ^th 2006, in Vale do Paraiba University, in Sao Jose dos Campos/SP and approved with distinction.

The research showed many advantages upon the traditional way to treat caries but it was necessary a very expansive motor drive (with sophisticated electronics and micro-mechanics) to remove caries in a very innovative way, never shown before.

In an in vivo situation (Figures A and B, in drawing attached document), there is practically no injure to the treated tissue (and consequently avoiding pain to the patient), meaning an absolute new way of treating caries with no noise, trauma, fear or pain in most treatments in children, adults and elderly people. To achieve this innovation attractive commercially, became necessary to create a simpler and lower cost micro- mechanics with electronic controls based on implant drive motor transformed to a compacted handpiece that could provide specific torque and speed (similar to the values of the research) for the treatment of every kind of caries, with all the advantages shown in the next pages, is the purpose of this document.

In the way to understand better the Ultra-Low Rotation micro- mechanics it is necessary to understand the caries disease and its characteristics that are resumed afterwards.

A dental caries is considered a multifactor and dynamic process characterized by alternating periods of destruction and repair in enamel, where the disease initiate. Preventive measures, like plaque control, a low carbohydrate diet and the increased resistance to bacterial acids related to a major exposure to fluorides, can help the tissue remineralization, also improving the enamel hardness.

When the disease progress the next tissue to be destructed is the dentin, that is a protected environment, moist, with cells, nutrients and innervations, and these seem to encourage the growth of anaerobic restrict bacteria (are killed in the presence of oxigen) becoming predominant (Larmas, 1971; Hoshino, 1985; Massey et al. 1993; Martin et al., 2002; Munson et al., 2004; Nadkarni et al., 2004; Chhour et al., 2005, Haraldsson, 2005) and the caries become larger inside the tooth many times with no signs outside. This progression is called Hidden Caries and it is growing according to many studies probably because fluorides make enamel harder for sure, but do not penetrate to dentin as much as necessary to avoid destruction of dentin tissue (Lussi, 1991; Kidd et al., 1992; Weerheijm 1992; Pearce, 1995; Weerheijm et al., 1997; Bloemendal, et al., 2004). Episodes of intense spontaneous pain can then occur (localized or irradiated in the face, suffering root canals procedures are necessary then, and in more advanced cases of destruction of large areas of dentin, compromising the structure for mastication, extraction may be necessary, unfortunately.

The classic concept of dental cavity removal is based upon removing the entire decayed dentine. The most superficial decayed part is heavily infected and composed of irreversible degraded collagen. Studies show the possibility of the more internal layer,

the affected dentine, to become mineralized, as long as there is enough decontamination through the removal of the infected layer (Fusayama et al., 1966; Kuboki et al., 1977).

The affected part (under the infected dentin) which is partially demineralized (soft in a certain degree), present intact collagen fibers, peritubular dentine, odontoblastic cells and tubules not infected by microorganisms. This tissue is sensitive and responds to mechanical and thermal stimuli, although it can be soft, it should not be removed because it will be harder again if bacteria is adequately removed or killed (ozonized water and/or ozonized gas or PDT necessary to achieve high rate of disinfection). An adequate diagnose is necessary, generally by fluorescence induced by laser.

When Ultra-Low Rotation is applied, it is noted in a tactile way that the tissue becomes harder as long as the mechanics reaches the healthy tissue, giving characteristics of self limiting, avoiding over treatment or the exposure of the pulp, that could lead to root canal treatment.

The removal of the decayed dentine is considered a critical phase during the cavity preparation in traditional diagnosis and treatment, since it implies in the complete removal of the enamel and irreversible disorganized dentine without including the healthy tissue, which must be preserved, because it is the best protection tissue for the dental pulp, but of difficult clinical execution in a non-traumatic form, due to the subjectivity of the tissue markers in order to know where there is a limit between healthy and infected tissue.

In resume dentists have difficulties to know exactly where and when to stop to remove tissue without

sophisticated diagnose methods, as laser induced fluorescence. The perception of micro-hardness tactilely through high speed drilling is also practically impossible, because there is no torque enough in turbines rotating in thousands per minute, avoiding the analysis of the consistence of the treated tissue, leading to over or under treatment.

Softness and no sensation of pain can be the makers for continuation of the treatment to remove caries with Ultra- Low Rotation. It can remove the weakened tissue very well, because it is projected to work with adequate torque, making dentists sense the consistency all the time during the procedure, working as an auxiliary diagnose mode for the dentin in vivo.

Fusayama (Tokyo University professor) and collaborators published an article in the mid 1960's (1966) demonstrating that the decayed dentine presents a low micro-hardness, while the reactive dentine shows an elevated micro-hardness. The values found are mentioned in Knoop micro-hardness and are similar, on average, to values found in more recent research. The micro-hardness areas only increase from dentine micro-regions which are free from micro-organisms.

Lussi (Bern University professor, in Switzerland), published an article in 1991 evaluating the micro-hardness of the healthy and decayed tissue samples, finding for the enamel healthy areas, an average of micro-hardness values of 300 Knoop (similar to steel) and for the healthy dentine, 60 Knoop; in the decayed enamel samples, it was obtained, on average, significantly lower values, being reduced to 60 Knoop and to 20 Knoop for decayed dentine.

Banerjee and collaborators in 1999 also evaluated the decayed and healthy dentine tissues, relating auto-

fluorescence in more infected areas to the lower Knoop micro-hardness. The values obtained were from 10,57 Knoop for the decayed necrotic area up to 64,17 Knoop for the healthy dentine. In this study, the removal of the decayed tissue with excavators can be guided by the absence of hardness shown by the dentine, being finished when the dentine is shown rigid again. After evaluation with laser confocal microscopy was finished, it was deduced, through Banerjee and his collaborators' work, that the dentist can guide himself by the low micro-hardness, which characterizes the decayed tissue and the high hardness shown by the translucent zone can represent a frontier between the healthy tissue fr< e of bacteria and the infected, irreversibly decomposed.

Mondei i (Main Professor at Bauru/USP

University) and collaborators evaluatet different types of geometric forms of dental cavities done with high rota ^t ion drills and concluded that the cavities preparation more than a quarter the intercuspid distance took to significantly higher dental fracture ris ¹ , s, confirming advantages from minimally invasive Odontology, where ^* is not proclaimed extension for prevention, the principle of cavity f/eparation proclaimed by Black (beginning of XX Century), considere d the father of Dentistry, who developed the cavity preparation techni'j αes performed even today in silver amalgam restorations, where there is he ^■ . lthy tissue removal for retention of the restoration.

The hisinry and the development of the rotary equipments are revised in works oy Yip and Samaranayake (1998). Despite the rotary mechanics used in dentistry are considered practically universal, there are still many proble ns to be surpassed. Some factors are

potentially responsible for the discomfort and pain which are associated with cavity preparation:

Vital dentine has high sensibility

(extremely innervated tissue) and respond immediately if damaged with pain;

Pressure during the mechanical preparation on dental tissue (that is, mechanical stimulus);

Bone-conducted vibration and noise (indirectly perceived by the ear); Micro-motor characteristic noise or dental turbine (which usually operate in 20 000 rpm (micro-motor) and from 100 to 400 000 rpm (turbine);

Development of high temperatures on the cutting surface; Possibility of generating pain by thermal stimulus;

Possibility of generating enamel cracks (friction in high level);

Risk of improperly penetrating healthy tissue due to not having any precise tactile sensation when using higher speeds, being possible of having a higher possibility of accidental pulp exposure and tissue over-treating;

Cross-contamination by aerosol created in refrigeration; Many studies show that the temperature on the drills cutting surface or diamond stones can easily go over the pain

threshold, even with spray for irrigation, and some damage to the subjacent pulp may happen.

Litsky and collaborators (1970) and Lewis and collaborators (1992) tell that the high rotation spray, by getting in contact with the cavity at a determined pressure produce a contaminated aerosol due to the dental particles suspension, restoring materials, microorganisms, saliva etc, which can attain distances which go beyond the operating area. The speeding drill cuts through the decayed dentine and eventually even expose healthy dentine tubules and in conjunction with the refrigerating water directly on the odontoblastic process, will result in pain associated to the cavity preparation through this convencional technique.

The traditional methods are more uncomfortable and include higher speeds of rotary mechanic work, besides the uncomfortable noise, there is a big possibility of generating pain due to the high friction and generated temperatures, besides the pulverized contaminated aerosol in the work area.

"CARIES REMOVAL PROCEDURE

AND RESULTING EQUIPMENT" object of this patent was developed to overcome the disadvantages, the inconveniences and the limitations of the present mechanical processes, since it presents a higher work precision.

The potential advantages of this technique which requires the adaptation of a micro-mechanic equipment is described below. a) The possibility of patient's suffering which the new process offers is considerably less if compared to the traditional mechanics, since it does not hit the vital dentine in a traumatic

form (there is absolute control over the access speed, which is much reduced) and it is minimally invasive; b) The pressure over the tissue is minimal, not being able of generating intense pain or cracks (generated by great friction); c) The vibration and the conducted bone noise can be considered minimal, since the decayed tissue is decomposed, offering low resistance, and in this way there is a low vibration indicator if compared, both to the traditional low speed mechanics (20.000 rpm), and to the high speed mechanics (120.000 to 400.000 rpm); d) There is not piercing noise (similar to a turbine), not causing traumas or psychosomatic reactions in the patient; e) There is no development of elevated temperatures on the cutting surface due to the extremely low speed, even when there is no continuous irrigation, not representing a thermal stimulus related to discomfort; f) Practically inexistent risk of pulp exposure (unless there is advanced decomposition of the dentine tissue including the pulp tissue, indicating probable tissue death associated to a complete sensibility absence during the mechanical access); g) There is no contaminated aerosol formation in the work place, since there is no significantly heat generation; h) Optionally, a high tissue disinfection can be obtained through PDT or Ozone therapy. The last one can be done during the mechanical removal with ozonized water application during preparation or after the end of the cavity preparation (with the application of ozonized water and ozonized gas) or only ozonized gas at the end of the

procedure, increasing the life time of the restoration based on the high bactericidal effect applied to the treated tissue. There is also the optional indication of liberating fluoride materials collocation, like the glass ionomer, for the continuous posterior tissue remineralization (considering the fluorides capacity of re-incorporation and gradual liberation at the dental surface, which is a glass ionomer cement basic chemical characteristic); i) The rotary excavation with ultra-low rotation developed here, presents an auto-limited propriety, since it does not easily remove the subjacent healthy tissue; j) There is no needing of cooling off the tooth, consequently the equipment can have a micro-camera in the head or through a fiber optic system generating, sensing and transmiting microscope images in real time for detailing the procedures, because there is no spray in the mouth. k) The coupling of an optic system for the transmission of images can represent an increase in the quality of the mechanical preparation, since visualization has high quality microscopic characteristics, increasing a lot the visual area of the professional; 1) Through this last item (k) it would also help the posture, since the professional would not need to be arched over the patient during the procedure, being able to follow what is being done in real time with a monitor over his head (similar to the ones of virtual reality) or near the dental chair; m) The coupling of a battery would allow for freedom in taking care of patients in places where access to electrical

energy are restricted, like villages or far away places and/or to let the procedure more comfortable to the dentist (wire-less); n) The possibility of making a lighter and less complex industrial equipment, would allow bigger commercial access; o) The rotary control optionally coupled near the thumb would avoid the need for an , extra piece during transport and at the office (pedal), simplifying its use. p) The pre; .2nce of rotary indicators

(colored led's) and led illumination in the operating area can offer better operational control characteristics and good illumination in the operating area, respectively; q) The electric I scheme disposition, potential transformei , rechargeable battery unit anc electronic control in a remote area, dimir ishes the weight of the handμi-ece, increasing the professional's com όrt;

In the procc is of the present patent, it is noticed v\ wen removing the

\ decayed tissue, V.y rotary technique by ultra-low rotation, ^ hat there is low i » tissue resistanc ;, easily forming debris, noticing a certain Mmilarity with manual instrur ient removal, with the great precision different and rotary constancy, wr ich minimizes risks both of exaggerated pressu.v; over the tissue (usual in excavating with a manual instrument) and _s of crack formation.

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Therefore, there is scientific and technical data for supporting the development of this handpiece proposed ϊύ this patent, for the removal of decomposed tissue, without offering the ri'ik of mechanical trauma, since the tissue presents no resistance and it is S ighly infected.

For a better comprehension of the present patent, it is enclosed the following drawings:

FIGURE 1., with the diagram of the rotary equipment of ultra-low rotary of the present patent; and

FIGURE 2., with the alternative diagram of the rotary equipment of ultra-low rotary of the present patent. The process of the present patent presents the following sequence:

I) conventional caries presence diagnostics through fluorescence induced by laser or other reliable conventional diagnostics method;

II) cavity preparation for the removal of decayed tissue with rotary equipment with ultra-low rotary with a speed varying from 30 to the maximum of 300 rpm with torques which can vary from 0, 1 to 5 Newton;

III) Adicionally, in an optional way, PDT or

Ozone therapy can be applied to assure the best disinfection to the treated tissue;

Alternately the process of the present patent could associate the utilization of conventional rotary equipment in average or high rotations in the beginning of cavity preparation, in order to speed up the process.

The rotary equipment of ultra-low rotation used in the process of the present patent is shown on diagrams on figure 1 (a and b), formed by a conventional drill optionally mounted on a converter adaptor from high to low rotation (1) inserted on a drill propelled point (2), connected to a reducing micro-mechanics from 16: 1 to 20:1 (2a) and set in motion by a step electric motor (3), fed by direct current supplied by battery or by conventional electric current or by alternate current electric

motor with frequency variant, or by any other electronic mode, for rotation control.

Alternatively, the rotary equipment of ultra-low rotation of the present patent, described in figure 2 (a and b), can be obtained by adapting a pneumatic conventional micro-motor, through one or more speed reducing boxes complements from 16:1 to 20: 1 (5) between the pneumatic micro-motor (6) with borden or multiflex coupling (7) and to the high or low speed drill propelled head (4), making use of the conventional drill (4a), optionally using the drill converter adaptor from high to low speed;